Efficacy of a stable broadly protective subunit vaccine platform against SARS-CoV-2 variants of concern

The emergence and ongoing evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the need for rapid vaccine development platforms that can be updated to counteract emerging variants of currently circulating and future emerging coronaviruses. Here we report the development of a "train model" subunit vaccine platform that contains a SARS-CoV-2 Wuhan S1 protein (the "engine") linked to a series of flexible receptor binding domains (RBDs; the "cars") derived from SARS-CoV-2 variants of concern (VOCs). We demonstrate that these linked subunit vaccines when combined with Sepivac SWE™, a squalene in water emulsion (SWE) adjuvant, are immunogenic in Syrian hamsters and subsequently provide protection from infection with SARS-CoV-2 VOCs Omicron (BA.1), Delta, and Beta. Importantly, the bivalent and trivalent vaccine candidates offered protection against some heterologous SARS-CoV-2 VOCs that were not included in the vaccine design, demonstrating the potential for broad protection against a range of different VOCs. Furthermore, these formulated vaccine candidates were stable at 2-8 °C for up to 13 months post-formulation, highlighting their utility in low-resource settings. Indeed, our vaccine platform will enable the development of safe and broadly protective vaccines against emerging betacoronaviruses that pose a significant health risk for humans and agricultural animals.

Characterization of colonization kinetics and virulence potential of Salmonella Enteritidis in chickens by photonic detection

The light emitting module lux operon (luxCDABE) of Photorhabdus luminescens can be integrated into a “dark” bacterium for expression under a suitable promoter. The technique has been used to monitor kinetics of infection, e.g., by studying gene expression in Salmonella using mouse models in vivo and ex vivo. Here, we applied the bioluminescence imaging (BLI) technique to track Salmonella Enteritidis (SEn) strains carrying the lux operon expressed under a constitutive promoter sequence (sigma 70) in chicken after oral challenge. Detectable photon signals were localized in the crop, small intestine, cecum, and yolk sac in orally gavaged birds. The level of colonization was determined by quantification of signal intensity and SEn prevalence in the cecum and yolk sac. Furthermore, an isogenic SEn mutant strain tagged with the lux operon allowed for us to assess virulence determinants regarding their role in colonization of the cecum and yolk sac. Interestingly, mutations of SPI-1(Salmonella Pathogenicity Island 1) and fur (ferric uptake regulator) showed significantly decreased colonization in yolk sac that was correlated with the BLI data. A similar trend was detected in a ΔtonB strain by analyzing enrichment culture data. The inherently low quantum yield, light scattering, and absorption by tissues did not facilitate detection of signals from live birds. However, the detection limit of lux operon has the potential to be improved by resonance energy transfer to a secondary molecule. As a proof-of-concept, we were able to show that sensitization of a fluorescent-bound molecule known as the lumazine protein (LumP) improved the limit of detection to a certain extent.

Enhancement of protective efficacy of innate immunostimulant based formulations against yolk sac infection in young chicks

This study was conducted to characterize and compare the protective effects of various innate immune stimulants against yolk sac infection (YSI) caused by an avian pathogenic Escherichia coli in young chicks. The immune stimulants were administered alone or in various combinations of unmethylated CpG oligodeoxynucleotides (CpG), polyinosinic:polycytidylic acid (Poly I:C), and avian antimicrobial peptides (AMPs). Routes included in ovo or in ovo followed by a subcutaneous (S/C) injection. CpG alone and in combination with Poly I:C, truncated avian cathelicidin (CATH)-1(6-26), avian beta defensin (AvBD)1, and CATH-1(6-26) + AvBD1, were administered in ovo to 18-day-old embryonated eggs for gene expression and challenge studies. Next, CpG alone and the potentially effective formulation of CpG + Poly I:C, were administrated via the in ovo route using 40 embryonated eggs. At 1 day post-hatch, half of each group also received their respective treatments via the S/C route. Four hours later, all chicks were challenged using E. coli strain EC317 and mortalities were recorded for 14 d. The first challenge study revealed that amongst the single use and combinations of CpG with different innate immune stimulants, a higher protection and a lower clinical score were offered by the combination of CpG + Poly I:C. The second challenge study showed that this combination (CpG + Poly I:C) provides an even higher level of protection when a second dose is administered via the S/C route at 1 day post-hatch. The current research highlights the efficacy of a combination of CpG + Poly I:C administered either in ovo or in ovo along with a S/C injection and its potential use as an alternative to antibiotics against yolk sac infection in young chicks.

Characterization of Dosage Levels for In Ovo Administration of Innate Immune Stimulants for Prevention of Yolk Sac Infection in Chicks

Innate immune stimulants, especially toll-like receptor (TLR) ligands and agonists, are the main players in the initiation of innate immunity and have been widely studied as alternatives to antibiotics to control infection. In the present study, we characterized the dosage levels of various innate immune stimulants, including unmethylated cytosine-phosphate-guanosine dinucleotide -containing oligodeoxynucleotides (CpG ODN), polyinosinic-polycytidylic acid (poly I:C), cyclic polyphosphazene 75B (CPZ75B), avian beta-defensin 2 (ABD2), and combinations of these reagents given in ovo. Data derived from a series of animal experiments demonstrated that the in ovo administration of 10–50 µg CpG ODN/embryo (on embryonic day 18) is an effective formulation for control of yolk sac infection (YSI) due to avian pathogenic Escherichia coli (E. coli) in young chicks. Amongst the different combinations of innate immune stimulants, the in ovo administration of CpG ODN 10 µg in combination with 15 µg of poly I:C was the most effective combination, offering 100% protection from YSI. It is expected that the introduction of these reagents to management practices at the hatchery level may serve as a potential replacement for antibiotics for the reduction of early chick mortality (ECM) due to YSI/colibacillosis.

High Affinity Iron Acquisition Systems Facilitate but Are Not Essential for Colonization of Chickens by Salmonella Enteritidis

The roles of TonB mediated Fe³⁺ (ferric iron) uptake via enterobactin (involving biosynthesis genes entABCDEF) and Fe²⁺ (ferrous iron) uptake through the FeoABC transporter are poorly defined in the context of chicken-Salmonella interactions. Both uptake systems are believed to be the major contributors of iron supply in the Salmonella life cycle. Current evidence suggests that these iron uptake systems play a major role in pathogenesis in mammals and as such, they represent promising antibacterial targets with therapeutic potential. We investigated the role of these iron uptake mechanisms regarding the ability of Salmonella Enteritidis (SEn) strains to colonize in a chicken infection model. Further we constructed a bioluminescent reporter to sense iron limitation during gastrointestinal colonization of Salmonella in chicken via ex vivo imaging. Our data indicated that there is some redundancy between the ferric and ferrous iron uptake mechanisms regarding iron acquisition during SEn pathogenesis in chicken. We believe that this redundancy of iron acquisition in the host reservoir may be the consequence of adaptation to unique avian environments, and thus warrants further investigation. To our knowledge, this the first report providing direct evidence that both enterobactin synthesis and FeoABC mediated iron uptake contribute to the virulence of SEn in chickens.

Iron-Uptake Systems of Chicken-Associated Salmonella Serovars and Their Role in Colonizing the Avian Host

Iron is an essential micronutrient for most bacteria. Salmonella enterica strains, representing human and animal pathogens, have adopted several mechanisms to sequester iron from the environment depending on availability and source. Chickens act as a major reservoir for Salmonella enterica strains which can lead to outbreaks of human salmonellosis. In this review article we summarize the current understanding of the contribution of iron-uptake systems to the virulence of non-typhoidal S. enterica strains in colonizing chickens. We aim to address the gap in knowledge in this field, to help understand and define the interactions between S. enterica and these important hosts, in comparison to mammalian models.

In Ovo Administration of Innate Immune Stimulants and Protection from Early Chick Mortalities due to Yolk Sac Infection

Omphalitis or yolk sac infection (YSI) and colibacillosis are the most common infectious diseases that lead to high rates of early chick mortalities (ECMs) in young chicks. Out of numerous microbial causes, avian pathogenic Escherichia coli (APEC) or extraintestinal pathogenic E. coli infections are considered the most common cause of these conditions. YSI causes deterioration and decomposition of yolk, leading to deficiency of necessary nutrients and maternal antibodies, retarded growth, poor carcass quality, and increased susceptibility to other infections, including omphalitis, colibacillosis, and respiratory tract infection. Presently, in ovo injection of antibiotics, heavy culling, or after hatch use of antibiotics is practiced to manage ECM. However, increased antibiotic resistance and emergence of "super bugs" associated with use or misuse of antibiotics in the animal industry have raised serious concerns. These concerns urgently require a focus on host-driven nonantibiotic approaches for stimulation of protective antimicrobial immunity. Using an experimental YSI model in newborn chicks, we evaluated the prophylactic potential of three in ovo-administered innate immune stimulants and immune adjuvants for protection from ECM due to YSI. Our data have shown >80%, 65%, and 60% survival with in ovo use of cytosine-phosphodiester-guanine (CpG) oligodeoxynucleotides (ODN), polyinosinic:polycytidylic acid, and polyphosphazene, respectively. In conclusion, data from these studies suggest that in ovo administration of CpG ODN may serve as a potential candidate for replacement of antibiotics for the prevention and control of ECM due to YSI in young chicks.

Bistable expression of CsgD in Salmonella enterica serovar Typhimurium connects virulence to persistence

Pathogenic bacteria often need to survive in the host and the environment, and it is not well understood how cells transition between these equally challenging situations. For the human and animal pathogen Salmonella enterica serovar Typhimurium, biofilm formation is correlated with persistence outside a host, but the connection to virulence is unknown. In this study, we analyzed multicellular-aggregate and planktonic-cell subpopulations that coexist when S. Typhimurium is grown under biofilm-inducing conditions. These cell types arise due to bistable expression of CsgD, the central biofilm regulator. Despite being exposed to the same stresses, the two cell subpopulations had 1,856 genes that were differentially expressed, as determined by transcriptome sequencing (RNA-seq). Aggregated cells displayed the characteristic gene expression of biofilms, whereas planktonic cells had enhanced expression of numerous virulence genes. Increased type three secretion synthesis in planktonic cells correlated with enhanced invasion of a human intestinal cell line and significantly increased virulence in mice compared to the aggregates. However, when the same groups of cells were exposed to desiccation, the aggregates survived better, and the competitive advantage of planktonic cells was lost. We hypothesize that CsgD-based differentiation is a form of bet hedging, with single cells primed for host cell invasion and aggregated cells adapted for persistence in the environment. This allows S. Typhimurium to spread the risks of transmission and ensures a smooth transition between the host and the environment.

Role of motAB in adherence and internalization in polarized Caco-2 cells and in cecal colonization of Campylobacter jejuni

Campylobacter jejuni, a gram-negative motile bacterium commonly found in the chicken gastrointestinal tract, is one of the leading causes of bacterial gastroenteritis in humans worldwide. An intact and functional flagellum is important for C. jejuni virulence and colonization. To understand the role of C. jejuni motility in adherence and internalization in polarized Caco-2 cells and in cecal colonization of chickens we constructed a C. jejuni NCTC11168 V1 deltamotAB mutant. The motAB genes code for the flagellar motor, which enables the rotation of the flagellum. The nonmotile deltamotAB mutant expressed a full-length flagellum, which allowed us to differentiate between the roles of full-length flagella and motility in the ability of C. jejuni to colonize. To study the adherence and invasion abilities of the C. jejuni deltamotAB mutant we chose to use polarized Caco-2 cells, which are thought to be more representative of in vivo intestinal cell architecture and function. Although the C. jejuni deltamotAB mutant adhered significantly better than the wild type to the Caco-2 cells, we observed a significant reduction in the ability to invade the cells. In this study we obtained evidence that the flagellar rotation triggers C. jejuni invasion into polarized Caco-2 cells and we believe that C. jejuni is propelled into the cell with a drill-like rotation. The deltamotAB mutant was also tested for its colonization potential in a 1-day-old chicken model. The nonmotile C. jejuni deltamotAB mutant was not able to colonize any birds at days 3 and 7, suggesting that motility is essential for C. jejuni colonization.

Salmonella vaccines in poultry: past, present and future

Salmonella species are important zoonotic pathogens that cause gastrointestinal disease in humans and animals. Poultry products contaminated with these pathogens are one of the major sources of human Salmonella infections. Vaccination of chickens, along with other intervention measures, is an important strategy that is currently being used to reduce the levels of Salmonella in poultry flocks, which will ultimately lead to lower rates of human Salmonella infections. However, despite numerous studies that have been performed, there is still a need for safer, well-defined Salmonella vaccines. This review examines the different classes of Salmonella vaccines that have been tested, highlighting the merits and problems of each, and provides an insight into the future of Salmonella vaccines and the platforms that can be used for delivery.

From Exit to Entry: Long-term Survival and Transmission of Salmonella

Salmonella spp. are a leading cause of human infectious disease worldwide and pose a serious health concern. While we have an improving understanding of pathogenesis and the host-pathogen interactions underlying the infection process, comparatively little is known about the survival of pathogenic Salmonella outside their hosts. This review focuses on three areas: (1) in vitro evidence that Salmonella spp. can survive for long periods of time under harsh conditions; (2) observations and conclusions about Salmonella persistence obtained from human outbreaks; and (3) new information revealed by genomic- and population-based studies of Salmonella and related enteric pathogens. We highlight the mechanisms of Salmonella persistence and transmission as an essential part of their lifecycle and a prerequisite for their evolutionary success as human pathogens.

Effect of the Salmonella pathogenicity island 2 type III secretion system on Salmonella survival in activated chicken macrophage-like HD11 cells

In order to better identify the role of the Salmonella pathogenicity island 2 (SPI-2) type III secretion system (T3SS) in chickens, we used the well-known gentamicin protection assay with activated HD11 cells. HD11 cells are a macrophage-like chicken cell line that can be stimulated with phorbol 12-myristate 13-acetate (PMA) to exhibit more macrophage-like morphology and greater production of reactive oxygen species (ROS). Activated HD11 cells were infected with a wild-type Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) strain, a SPI-2 mutant S. Typhimurium strain, a wild-type Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) strain, a SPI-2 mutant S. Enteritidis strain, or a non-pathogenic Escherichia coli (E. coli) strain. SPI-2 mutant strains were found to survive as well as their parent strain at all time points post-uptake (PU) by the HD11 cells, up to 24 h PU, while the E. coli strain was no longer recoverable by 3 h PU. We can conclude from these observations that the SPI-2 T3SS of S. Typhimurium and S. Enteritidis is not important for survival of Salmonella in the activated macrophage-like HD11 cell line, and that Salmonella must employ other mechanisms for survival in this environment, as E. coli is effectively eliminated.

Protection of epithelial cells from Salmonella enterica serovar Enteritidis invasion by antibodies against the SPI-1 type III secretion system

Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) is one of the major causes of bacterial food-borne illness in humans. During the course of infection, Salmonella Enteritidis uses 2 type III secretion systems (T3SS), one of which is encoded on Salmonella pathogenicity island 1 (SPI-1). SPI-1 plays a major role in the invasion process. In the present study, we evaluated the effect of sera against the SPI-1 T3SS components on invasion in vitro using polarized human intestinal epithelial cells (Caco-2). Antisera to SipD protected Caco-2 cells against entry of wild-type Salmonella Enteritidis. On the other hand, sera against InvG, PrgI, SipA, SipC, SopB, SopE, and SopE2 did not affect Salmonella Enteritidis entry. To illustrate the specificity of anti-SipD mediated inhibition, SipD-specific antibodies were depleted from the serum. Antiserum depleted of SipD-specific antibodies lost its capacity to inhibit Salmonella Enteritidis entry. Thus, we demonstrate for the first time that antibodies against the SPI-1 needle tip protein (SipD) inhibit Salmonella Enteritidis invasion and that the SipD protein may be an important target in blocking SPI-1 mediated virulence of Salmonella Enteritidis.

Salmonella enterica subspecies enterica serovar Enteritidis Salmonella pathogenicity island 2 type III secretion system: role in intestinal colonization of chickens and systemic spread

Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) has been identified as a significant cause of salmonellosis in humans. Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) each encode a specialized type III secretion system (T3SS) that enables Salmonella to manipulate host cells at various stages of the invasion/infection process. For the purposes of our studies we used a chicken isolate of S. Enteritidis (Sal18). In one study, we orally co-challenged 35-day-old specific pathogen-free (SPF) chickens with two bacterial strains per group. The control group received two versions of the wild-type strain Sal18: Sal18 attTn7 : : tet and Sal18 attTn7 : : cat, while the other two groups received the wild-type strain (Sal18 attTn7 : : tet) and one of two mutant strains. From this study, we concluded that S. Enteritidis strains deficient in the SPI-1 and SPI-2 systems were outcompeted by the wild-type strain. In a second study, groups of SPF chickens were challenged at 1 week of age with four different strains: the wild-type strain, and three other strains lacking either one or both of the SPI-1 and SPI-2 regions. On days 1 and 2 post-challenge, we observed a reduced systemic spread of the SPI-2 mutants, but by day 3, the systemic distribution levels of the mutants matched that of the wild-type strain. Based on these two studies, we conclude that the S. Enteritidis SPI-2 T3SS facilitates invasion and systemic spread in chickens, although alternative mechanisms for these processes appear to exist.

Comparative genomic hybridization and physiological characterization of environmental isolates indicate that significant (eco-)physiological properties are highly conserved in the species Escherichia coli

Escherichia coli, the common inhabitant of the mammalian intestine, exhibits considerable intraspecies genomic variation, which has been suggested to reflect adaptation to different ecological niches. Also, regulatory trade-offs, e.g. between catabolic versatility and stress protection, are thought to result in significant physiological differences between strains. For these reasons, the relevance of experimental observations made for 'domesticated' E. coli strains with regard to the behaviour of this species in its natural environments is often questioned and doubts are frequently raised on the status of E. coli as a defined species. The variability of important (eco-)physiological functions, such as carbon substrate uptake and breakdown capabilities, as well as stress defence mechanisms, in the genomes of commensal and pathogenic E. coli strains were therefore investigated. Furthermore, (eco-)physiological properties of environmental strains were compared to standard laboratory strain K-12 MG1655. Catabolic, stress protection, and carbon- and energy source transport operons showed a very low intraspecies variability in 57 commensal and pathogenic E. coli. Environmental isolates adapted to glucose-limited growth in a similar way as E. coli MG1655, namely by increasing their catabolic flexibility and by inducing high-affinity substrate uptake systems. The results obtained indicate that significant (eco-)physiological properties are highly conserved in the natural population of E. coli. This questions the proposed dominant role of horizontal gene transfer for niche adaptation.

[Treatment of chronic pain in the internist's practice]

Chronic pain is one of the most frequent complaints in outclinic supply. Careful anamnesis and physical examination are in the focus of diagnostic procedure. Their results will give strong evidence for the underlying pathogenesis. Nevertheless, the perception of pain remains completely subjective and can be only measured by asking the patient. Therefore, a multitude of validated instruments has been developed ranging from the simple intensity rating scales up to sophisticated questionnaires. Both, the diagnostic and therapeutic procedures should adhere to the bio-psycho-social concept of pain. Medical treatment should be executed in accordance to the WHO Guidelines for Cancer Pain Treatment. But for the majority of patients, multidisciplinary concepts are required including psychotherapy and iatrophysics.

Divalent metal transport in the green microalga Chlamydomonas reinhardtii is mediated by a protein similar to prokaryotic Nramp homologues

Information about the molecular mechanisms of metal transport in algae is scarce, despite the significant status these organisms have in aquatic ecosystems. In the present study, we describe the cloning and functional characterization of a divalent metal transporter (named DMT1) in the green microalga Chlamydomonas reinhardtii Dangeard. The longest open reading frame of the cloned DMT1 cDNA encodes a protein of 513 amino acids with 11 putative transmembrane domains. The protein belongs to the Nramp family of divalent metal transporters and shows surprisingly higher similarity to some prokaryotic than to eukaryotic polypeptides. Especially the N-terminus, which is longer than of every other homologue considered in this study, displays--uniquely among selected eukaryotic Nramps--exclusively prokaryotic characteristics. Functional complementation experiments in yeast strains with impaired metal transport systems, revealed that C. reinhardtii DMT1 has a broad specificity, acting in the transport of several divalent metals (manganese, iron, cadmium, copper), but excluding zinc.

[Early and late complications of chemotherapy of solid tumors]

Treatment with cytostatic agents is associated with both acute side effects such as nausea, emesis, blood count changes, and allergic reactions, and late complications such as cardiac, renal or gastrointestinal toxicity. In addition to differences in substance groups, intra-individual variations on the part of patients, and their general and nutritional status, are of particular importance for the severity of such side effects. For improved treatment monitoring, side effects should be recorded and documented in accordance with common toxicity criteria. In view of the complexity of oncological treatment, including the optimal supporting measures, such treatments should remain in the hands of oncological specialists.

Transition metal transport in the green microalga Chlamydomonas reinhardtii—genomic sequence analysis

Uptake and export systems play a major role in transition metal homeostasis. The objective of this study was to identify potential metal transport mechanisms in the green microalga Chlamydomonas reinhardtii. We concentrated on the four major transition metal transporter families found in plants and other organisms: the ZIP, CDF and Nramp families, and the CPx-ATPases. Using the information available for these protein families we performed comparative sequence analysis in the recently released genome of C. reinhardtii. Using this approach we were able to identify members of all four transporter families (four ZIPs, one CDF, two CPx-ATPases, and five Nramps). These findings advance our current knowledge of the metal transport processes present in C. reinhardtii. In addition, by subsequent in silico splicing of the genomic sequence we obtained cDNA sequences which led to the identification of ESTs (expressed sequence tags) in the C. reinhardtii EST database. These identified ESTs will be valuable for the cloning and characterization of several metal transporters utilized by the alga.

Ferric hydroxamate binding protein FhuD from Escherichia coli: mutants in conserved and non-conserved regions

Uptake of iron complexes into the gram-negative bacterial cell requires highly specific outer membrane receptors and specific ATP-dependent (ATP-Binding-Cassette (ABC)) transport systems located in the inner membrane. The latter type of import system is characterized by a periplasmic binding protein (BP), integral membrane proteins, and membrane-associated ATP-hydrolyzing proteins. In gram-positive bacteria lacking the periplasmic space, the binding proteins are lipoproteins tethered to the cytoplasmic membrane. To date, there is little structural information about the components of ABC transport systems involved in iron complex transport. The recently determined structure of the Escherichia coli periplasmic ferric siderophore binding protein FhuD is unique for an ABC transport system (Clarke et al. 2000). Unlike other BP's, FhuD has two domains connected by a long alpha-helix. The ligand binds in a shallow pocket between the two domains. In vivo and in vitro analysis of single amino acid mutants of FhuD identified several residues that are important for proper functioning of the protein. In this study, the mutated residues were mapped to the protein structure to define special areas and specific amino acid residues in E. coli FhuD that are vital for correct protein function. A number of these important residues were localized in conserved regions according to a multiple sequence alignment of E. coli FhuD with other BP's that transport siderophores, heme, and vitamin B12. The alignment and structure prediction of these polypeptides indicate that they form a distinct family of periplasmic binding proteins.

Identification of the periplasmic cobalamin-binding protein BtuF of Escherichia coli

Cells of Escherichia coli take up vitamin B(12) (cyano-cobalamin [CN-Cbl]) and iron chelates by use of sequential active transport processes. Transport of CN-Cbl across the outer membrane and its accumulation in the periplasm is mediated by the TonB-dependent transporter BtuB. Transport across the cytoplasmic membrane (CM) requires the BtuC and BtuD proteins, which are most related in sequence to the transmembrane and ATP-binding cassette proteins of periplasmic permeases for iron-siderophore transport. Unlike the genetic organization of most periplasmic permeases, a candidate gene for a periplasmic Cbl-binding protein is not linked to the btuCED operon. The open reading frame termed yadT in the E. coli genomic sequence is related in sequence to the periplasmic binding proteins for iron-siderophore complexes and was previously implicated in CN-Cbl uptake in Salmonella. The E. coli yadT product, renamed BtuF, is shown here to participate in CN-Cbl uptake. BtuF protein, expressed with a C-terminal His(6) tag, was shown to be translocated to the periplasm concomitant with removal of a signal sequence. CN-Cbl-binding assays using radiolabeled substrate or isothermal titration calorimetry showed that purified BtuF binds CN-Cbl with a binding constant of around 15 nM. A null mutation in btuF, but not in the flanking genes pfs and yadS, strongly decreased CN-Cbl utilization and transport into the cytoplasm. The growth response to CN-Cbl of the btuF mutant was much stronger than the slight impairment previously described for btuC, btuD, or btuF mutants. Hence, null mutations in btuC and btuD were constructed and revealed that the btuC mutant had a strong impairment similar to that of the btuF mutant, whereas the btuD defect was less pronounced. All mutants with defective transport across the CM gave rise to frequent suppressor variants which were able to respond at lower levels of CN-Cbl but were still defective in transport across the CM. These results finally establish the identity of the periplasmic binding protein for Cbl uptake, which is one of few cases where the components of a periplasmic permease are genetically separated.

Inactivation of Bacillus subtilis spores and formation of bromate during ozonation

Inactivation of B. subtilis spores with ozone was investigated to assess the effect of pH and temperature, to compare the kinetics to those for the inactivation of C. parvum oocysts, to investigate bromate formation under 2-log inactivation conditions, and to assess the need for bromate control strategies. The rate of B. subtilis inactivation with ozone was independent of pH, decreased with temperature (activation energy of 42,100 Jmol(-1)), and was consistent with the CT concept. B. subtilis was found to be a good indicator for C. parvum at 20-30 degrees C, but at lower temperatures B. subtilis was inactivated more readily than C. parvum. Bromate formation increased as both pH and temperature increased. For water with an initial bromide concentration of 33 microgl(-1), achieving 2-logs of inactivation, without exceeding the 100 microg l(-1) bromate standard, was most difficult at 30 degrees C for B. subtilis and at midrange temperatures (10-20 degrees C) for C. partum. pH depression and ammonia addition were found to reduce bromate formation without affecting B. subtilis inactivation, and may be necessary for waters containing more than 50 microgl(-1) bromide.

Identification of recurrent and novel mutations in the LDL receptor gene in German patients with familial hypercholesterolemia

In order to identify mutations in the low density lipoprotein receptor (LDLR) gene in primary hypercholesterolemia, we screened 100 unrelated German individuals with elevated plasma LDL-C (LDL-C > 4,7 mmol/l) for mutations in the 18 exons and their flanking intronic sequences including the promoter region of the LDL-R gene using a combination of polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and direct sequencing. In addition we tested all patients for the presence of mutations in codons 3456 - 3553 of the gene encoding apolipoprotein B-100. In 56 individuals we detected 37 different mutations affecting the LDL-R gene, 16 of which, designated C122R, C127Y, C163W, F179L, R236W, E296X, R553C, V618D, T721I, V785D, G1358+2A, 257delTCTGGAGGT, 657delC, 676insACGGTATGGACTGCAdelGACG, C1205delTCT, 2420delTCCTTCT, have not yet been reported. One proband was a compound heterozygote showing two separate sequence variations (E207X and T705I). Seven patients were heterozygous for the mutation R3500Q within the apoB-100 gene. These results demonstrate that there is a broad spectrum of mutations in the LDL-R gene and that the R3500Q mutation is a frequent cause of hypercholesterolemia in the German population.

[60-year-old patient with fever, jaundice and intra-abdominal lymphomas]

BACKGROUND

Infectious mononucleosis usually manifests in adolescents and young adults. Medical history in elderly patients is often atypical and severe.

CASE REPORT

We report on the medical history of a 60-year-old woman, who came into our hospital with fever, icterus, decreasing performance status and abdominal pain. Splenomegaly and multiple abdominal lymph nodes could be found by ultrasound and CT scan. Endoscopically severe mucosal alterations could be found in the upper and lower gastrointestinal tract. Serologically, an acute EBV infection was diagnosed. With symptomatic treatment, the clinical course was without any problems.

CONCLUSION

Casuistically, we described the atypical medical history of an elderly patient with infectious mononucleosis. In each undefined lymphadenopathy of elderly patients, an EBV infection should be included into the differential diagnosis.

ABC transporter-mediated uptake of iron, siderophores, heme and vitamin B12

Microbes have developed a number of different strategies to utilize iron, which is a vital element for most organisms but not always readily available from the environment. Based on experimental studies and sequence analysis data, this article gives a short overview of ABC transporters related to iron uptake: components of three distinct families mediate the translocation of iron, siderophores, heme and vitamin B12 across the cytoplasmic membrane of bacteria.

Apolipoprotein E1 Baden (Arg(180)-->Cys). A new apolipoprotein E variant associated with hypertriglyceridemia

Apolipoprotein (apo) E mediates the removal of chylomicron and very low density lipoprotein remnants from plasma. It is polymorphic in sequence and the products of the three common alleles (epsilon 2, epsilon 3, epsilon 4) differ from one another in their binding to lipoprotein receptors. ApoE2 is defective in binding and homozygosity for apoE2 is associated with type III hyperlipoproteinemia (HLP). Other rare isoforms of apoE have been found to be associated either with dominant type III HLP or with the development of hypertriglyceridemia. We identified a 42 year-old hypertriglyceridemic woman with an apoE phenotype 3/1. Restriction isotyping using AflIII/HaeII resulted in an apparent apoE genotype 3/2, suggesting that the mutation occurred in an epsilon 2 allele. DNA sequence analysis revealed a C-->T point mutation at the first position of the codon for amino acid residue 180 of the mature apoE. This predicted a change Arg(180)-->Cys. The mutation altered a recognition site for the endonuclease HaeII, which allowed us rapidly to screen for this mutation. In relatives of the proband, apoE1 Baden was consistently associated with hypertriglyceridemia. Similar to other apoE variants linked to hypertriglyceridemia, the Arg(180)-->Cys mutation is located within the lipid binding domain of apoE. We therefore suggest that apoE1 Baden may cause hypertrigylceridemia, possibly by inhibiting the hydrolysis of triglycerides associated with very low density lipoproteins.

[Chemotherapy in colorectal carcinoma. From "one-drug-show" to therapeutic multiplicity]

Over the past decade, the chemotherapeutic options in the treatment of colorectal carcinoma have improved considerably. Up into the nineties, chemotherapy for this condition was purely a "one-drug show", while, today, a range of effective substances and combinations are available, and these have considerably improved the prognosis of this tumour entity. Both the first and second line treatments are today firmly established. Determination of the most appropriate sequence and combination of these new drugs (primary combination therapy, sequential administration of the substances, etc.) is the subject of ongoing and planned future studies.

[Infusiontherapy with 5-fluorouracil ("infusional" 5-FU) in solid tumors]

BACKGROUND

5-FU is an important anticancer agent for many tumor entities. Because of the historical development of this compound it was predominantly administered as a bolus application, although it was well known that the antineoplastic activity of this antimetabolite is improved by prolonged administration schedules (protracted infusion ["infusional"] of 5-FU). Since port-a-cath systems and portable pumps became available, "infusional" 5-FU containing chemotherapies were intensively investigated in various tumors known to be susceptible to 5-FU.

INDICATIONS

The largest experience with "infusional" 5-FU +/- folinic acid +/- other cytostatic drugs exists in gastrointestinal tumors. Meanwhile this way of 5-FU application is well established in the first- and second-line chemotherapy of metastatic colorectal and gastric cancer where it contributes to a clinically relevant improvement of the prognosis of these tumors. Other tumor entities where "infusional" 5-FU-based chemotherapies showed first positive results are i.e. breast cancer and esophageal cancers.

HDL steady state levels are not affected, but HDL apoA-I turnover is enhanced by Lifibrol in patients with hypercholesterolemia and mixed hyperlipidemia

Lifibrol (4-(4'-tert-butylphenyl)-1-(4'carboxyphenoxy)-2-butanol) is a new hypocholesterolemic drug effectively reducing total cholesterol, LDL cholesterol, and apolipoprotein (apo) B in experimental animals and in humans. In contrast to fibrates and HMG-CoA reductase inhibitors the cholesterol and triglyceride lowering effect of Lifibrol is not accompanied by increases in HDL cholesterol and apoA-I levels. We examined the impact of Lifibrol on the metabolism of HDL apoA-I in patients with hyperlipoproteinemia, using endogenous labeling with stable isotopes. Kinetic studies were performed in five male hypercholesterolemic individuals (type IIa), before and on treatment with 450 mg of Lifibrol daily for 4 weeks and in five male individuals suffering from mixed hyperlipidemia (type IIb), before and on therapy, for 12 weeks. Lifibrol reduced total cholesterol by 14% (P=0.02) and LDL cholesterol by 16% (P=0. 014) in all patients, and decreased triglycerides by 34% in type IIb patients. During Lifibrol therapy, HDL cholesterol and ApoA-I concentrations did not change. Tracer kinetics revealed that the fractional catabolic rate (FCR) of HDL apoA-I increased by 22% (P=0. 013). This increase in the apoA-I FCR was accompanied by a 23% increase in HDL apoA-I production rate (P=0.006). We conclude that Lifibrol, although not changing HDL steady state concentrations, enhances the turnover of apoA-I containing HDL particles.

Lifibrol enhances the low density lipoprotein apolipoprotein B-100 turnover in patients with hypercholesterolemia and mixed hyperlipidemia

Lifibrol (4-(4'-tert-butylphenyl)-1-(4'carboxyphenoxy)-2-butanol), a new hypocholesterolemic drug, effectively reduces total cholesterol (CH), low density lipoprotein (LDL)-CH, and apolipoprotein (apo) B in experimental animals and in humans. The impact of Lifibrol on the metabolism of apoB-100 containing lipoproteins in patients with hyperlipoproteinemia using endogenous labeling with stable isotopes is examined. Kinetic studies were performed in four male hypercholesterolemic individuals (type IIa) before and on treatment with 450 mg of Lifibrol daily for 4 weeks, and in five male individuals suffering from mixed hyperlipidemia (type IIb) before and on therapy for 12 weeks. Kinetic parameters were estimated by multicompartmental modeling. Lifibrol therapy reduced total CH by 16% (P = 0.012) in all patients, increased triglycerides (TG) by 11% (not significant) in type IIa patients and decreased TG by 34% (P = 0.059) in type IIb patients. During Lifibrol therapy, LDL apoB-100 concentrations decreased by 19% (P = 0.011) in all patients. The decrease in LDL apoB concentrations with Lifibrol therapy was due to an overall increase (75%, P = 0.006) of the fractional catabolic rates (FCR) of LDL apoB. This increase was partially attenuated by a 33% increase in LDL apoB production rate (PR) (P = 0.041). The overall production of apoB increased only slightly. Our data suggest that the major mechanism by which Lifibrol lowers LDL-CH is an increase in receptor-mediated catabolism of LDL rather than a decrease in hepatic apoB production.

Analysis of the new indirect revascularization method by determining objective parameters of clinical chemistry, histo-chemistry and histology

OBJECTIVE

This experimental study was initiated to determine whether transmyocardial laser revascularization (TMLR) after acute myocardial ischemia may improve clinical chemistry and diminish the amount of necrosis. In addition, the influence of TMLR on healthy myocardium was analyzed.

METHODS

The prolonged short-term effectiveness of TMLR was evaluated in 44 open-chest anesthetized pigs with (n = 21) or without (n = 23) the setting of acute myocardial ischemia (observation period 6 h): seven pigs served as controls (thoracotomy only). An additional seven pigs had left anterior descending artery (LAD) occlusion only (ischemia group). A subsequent 14 pigs were treated by TMLR (CO2) prior to LAD occlusion: Seven pigs received one laser channel/cm2 (group 1) and in seven pigs two channels/cm2 in the LAD territory (group 2) were performed. In addition, 16 pigs underwent TMLR without ischemia: Eight pigs received one channel/cm2 (group 3) and eight pigs two channels/cm2 (group 4). Clinical chemistry, histo-chemical assessment and histology were performed.

RESULTS

TMLR limits the expansion of the myocardial infarction zone: laser group 2 indicated a significant smaller area of necrosis in the area at risk (ischemic group (31%) vs. laser group 1 (19%), P = ns; laser group 2 (7%) vs. ischemic group, P < 0.01; laser group 1 vs. 2, P < 0.01). The amount of the area of necrosis and ischemia of laser groups 3 and 4 compared with control did not differ significantly (P = ns). Preventive creation of microchannels before ischemia did not diminish ischemic parameters (P = ns). The myocardial water content-measurements (MWC) in the ischemia, laser 1 and 2 groups did not show any difference at the end of the experiment, except higher values of laser group 2 (P < 0.05). Laser groups 3 and 4 revealed significantly higher MWC values compared with control (P < 0.001).

CONCLUSIONS

This prolonged acute study demonstrates that CO2-TMLR significantly reduces the amount of necrosis in the area at risk, but does not reduce cardiac ischemic markers. In healthy myocardium, TMLR significantly increases myocardial water content and ischemic parameters and induces small ischemic and very small necrotic areas surrounding open laser channels. Generally, the elevated cardiac enzymes and proteins are mainly attributed to the expected rise caused by vaporization of myocardial tissue in all laser groups.

Transport activity of FhuA, FhuC, FhuD, and FhuB derivatives in a system free of polar effects, and stoichiometry of components involved in ferrichrome uptake

The Escherichia coli fhu operon, composed of the fhuA, C, D, and B genes, is essential for the utilization of ferric siderophores of the hydroxamate type and for the uptake of the antibiotic albomycin. We have had difficulty studying the effects of missense mutations in individual plasmid-encoded transport genes because appropriate test strains were not found: all isolated chromosomal mutations in either one of the fhu genes (with a complete loss of function) negatively influenced the expression of other fhu genes in the operon. In order to analyze Fhu mutant proteins in a system free of polar effects, we constructed a plasmid-encoded gene cassette system by introducing unique restriction sites that allowed precise cloning of individual fhu genes. The fhu cassette operon expressed in a chromosomal fhu deletion mutant enabled us to evaluate the transport activity of mutated FhuA, FhuC, FhuD or FhuB derivatives. In addition, we found that transport across the outer membrane (via FhuA, TonB, ExbB, D) rather than transport across the cytoplasmic membrane (via FhuC, D, B) was rate limiting. The stoichiometry of the components involved in the uptake of iron(III) hydroxamates seems to be important for proper functioning.

Conserved amino acids in the N- and C-terminal domains of integral membrane transporter FhuB define sites important for intra- and intermolecular interactions

Transport of iron(III) hydroxamates across the inner membrane of Escherichia coli is mediated by a peri-plasmic binding protein-dependent transport (PBT) mechanism. FhuB, the integral membrane component of the system, is composed of covalently linked halves (FhuB[N] and FhuB[C]) which still function when present as two distinct polypeptide chains. Our analysis of two uptake-deficient FhuB derivatives provides evidence for a mechanistically novel type of functional complementation: 'domain displacement' in the cyto-plasmic membrane. Amino acid residues 60 and 426 in the FhuB polypeptide chain may define key positions that are important for FhuB[N]-FhuB[C] interaction. Furthermore, FhuB derivatives, altered in either one of their conserved regions--typical of PBT related integral membrane proteins--displayed a dominant negative effect on ferric hydroxamate transport. The experimental data suggest that the two functionally equivalent conserved regions in FhuB[N] and FhuB[C] are primarily involved in the interaction with another component of the transport system, probably FhuC.

Ferric rhizoferrin uptake into Morganella morganii: characterization of genes involved in the uptake of a polyhydroxycarboxylate siderophore

Iron uptake in Morganella morganii, mediated by the fungal siderophore rhizoferrin, was studied. A Mud1 insertion mutant devoid of growth on ferric rhizoferrin was complemented by a chromosomal DNA fragment of M. morganii that encoded an outer membrane protein and a periplasmic protein named RumA and RumB (for rhizoferrin uptake into Morganella spp.), respectively. rumA and rumB have the same transcription polarity and are probably cotranscribed from an iron-regulated promoter upstream of rumA. A predicted Fur regulatory sequence upstream of rumA was confirmed by the Fur titration assay. At the N terminus of RumA, a putative TonB box contains a proline residue that inactivates TonB-dependent receptors and colicins when introduced at the same position into TonB boxes of Escherichia coli. Analysis of a 10-kb sequence flanking rumA and rumB on both sides revealed seven additional open reading frames for which no role in ferric rhizoferrin uptake could be discerned. Thus, rumA and rumB, both essential for transport of this siderophore, form an isolated operon. Additional genes required for ferric rhizoferrin translocation across the cytoplasmic membrane must map at sites distinct from rumA and rumB. Transport studies revealed that both 55Fe3+ and [3H]ketorhizoferrin are incorporated by M. morganii, demonstrating that rhizoferrin serves as a true iron carrier.

Ferrichrome transport in Escherichia coli K-12: altered substrate specificity of mutated periplasmic FhuD and interaction of FhuD with the integral membrane protein FhuB

FhuD is the periplasmic binding protein of the ferric hydroxamate transport system of Escherichia coli. FhuD was isolated and purified as a His-tag-labeled derivative on a Ni-chelate resin. The dissociation constants for ferric hydroxamates were estimated from the concentration-dependent decrease in the intrinsic fluorescence intensity of His-tag-FhuD and were found to be 0.4 microM for ferric aerobactin, 1.0 microM for ferrichrome, 0.3 microM for ferric coprogen, and 5.4 microM for the antibiotic albomycin. Ferrichrome A, ferrioxamine B, and ferrioxamine E, which are poorly taken up via the Fhu system, displayed dissociation constants of 79, 36, and 42 microM, respectively. These are the first estimated dissociation constants reported for a binding protein of a microbial iron transport system. Mutants impaired in the interaction of ferric hydroxamates with FhuD were isolated. One mutated FhuD, with a W-to-L mutation at position 68 [FhuD(W68L)], differed from wild-type FhuD in transport activity in that ferric coprogen supported promotion of growth of the mutant on iron-limited medium, while ferrichrome was nearly inactive. The dissociation constants of ferric hydroxamates were higher for FhuD(W68L) than for wild-type FhuD and lower for ferric coprogen (2.2 microM) than for ferrichrome (156 microM). Another mutated FhuD, FhuD(A150S, P175L), showed a weak response to ferrichrome and albomycin and exhibited dissociation constants two- to threefold higher than that of wild-type FhuD. Interaction of FhuD with the cytoplasmic membrane transport protein FhuB was studied by determining protection of FhuB degradation by trypsin and proteinase K and by cross-linking experiments. His-tag-FhuD and His-tag-FhuD loaded with aerobactin specifically prevented degradation of FhuB and were cross-linked to FhuB. FhuD loaded with substrate and also FhuD free of substrate were able to interact with FhuB.

In vivo reconstitution of an active siderophore transport system by a binding protein derivative lacking a signal sequence

Transport of iron (III) hydroxamates across the inner membrane of Escherichia coli depends on a binding protein-dependent transport system composed of the FhuB, C and D proteins. The FhuD protein, which is synthesized as a precursor and exported through the cytoplasmic membrane, represents the periplasmic binding protein of the system, accepting as substrates a number of hydroxamate siderophores and the antibiotic albomycin. A FhuD derivative, carrying an N-terminal His-tag sequence instead of its signal sequence and therefore not exported through the inner membrane, was purified from the cytoplasm. Functional activity, comparable to that of wild-type FhuD, was demonstrated for this His-tag-FhuD in vitro by protease protection experiments in the presence of different substrates, and in vivo by reconstitution of iron transport in a fhuD mutant strain. The experimental data demonstrate that the primary sequence of the portion corresponding to the mature FhuD contains all the information required for proper folding of the polypeptide chain into a functional solute-binding protein. Moreover, purification of modified periplasmic proteins from the cytosol may be a useful approach for recovery of many polypeptides which are normally exported across the inner membrane and can cause toxicity problems when overproduced.