Effects of infectious hematopoietic necrosis virus and infectious pancreatic necrosis virus infection on hematopoietic precursors of the zebrafish

The zebrafish Danio rerio is a new model system for studying the genetics of hematopoiesis. To define naturally occurring viruses which could infect and replicate within hematopoietic precursors of the zebrafish, infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV) were studied. Infection of whole fish with viral supernatants demonstrated infectious replicants for both viruses, indicating that the virus host range includes the zebrafish. In other species, infection with these viruses leads to prominent hematopoietic necrosis of the head kidney, the major site of adult hematopoiesis. We detected a transient toxicity of the virus to hematopoietic precursors and terminally differentiated red cells after viral infections. The kinetics of hematopoietic defects between IHNV and IPNV infection differed; fish infected with either virus, however, recovered by 6 days postinfection. In contrast to other fish infected with the virus, hematocrit did not change appreciably during this time. These studies are the first to demonstrate IHNV and IPNV infection of the zebrafish and reveal the potential for use of such viruses for gene transfer experiments to infect zebrafish hematopoietic cells.

Calcium confusion--is the variability in calcium response by Sertoli cells to specific hormones meaningful or simply redundant?

When results of more than ten different studies on hormone-induced calcium signals in Sertoli cells are taken together, a wide variety of responses emerges. The reported changes range from increased concentrations, via no response at all, to decreased calcium concentrations. Minor variations in cell isolation techniques, culture conditions, or techniques for measuring the intracellular calcium could explain some of these differences. However, erratic variations in response are also observed within research groups under very similar experimental conditions. Such 'negative' findings are mainly reported orally and do not further penetrate the scientific community. As hormone-dependent calcium responses evidently may depend very much on the context of the cells, calcium transients would appear to be unreliable bioassay principles with which to detect the primary actions of FSH and effectors such as androgens on Sertoli cells. A more important biological question is whether these sometimes opposed calcium transients are connected with a particular cellular response. To date there is no evidence for such a tight coupling in Sertoli cells, implying that, at least under in vitro conditions, calcium signals might even be redundant altogether. Such calcium variability is probably not unique to Sertoli cells, and the aim of this commentary is to promote an open debate that may help to transform the current state of 'calcium confusion' into a better understanding of the intracellular calcium language.

Rapid androgen actions on calcium signaling in rat sertoli cells and two human prostatic cell lines: similar biphasic responses between 1 picomolar and 100 nanomolar concentrations

Androgen-induced calcium fluxes and gap junctional intercellular communication (GJIC) were studied in three different cell types. A transient (2-3 min duration) increase in intracellular calcium levels was observed within 20-30 sec of androgen addition, which was followed by a plateau phase with steroid concentrations higher than 1 nM. The kinetics of the calcium responses were similar in immature rat Sertoli cells, which contain normal nuclear receptors; the human prostatic tumor cell line, LNCaP, which contains a mutated nuclear receptor; and the human prostatic cell line, PC3, which does not contain a nuclear receptor. The human A431 tumor cell line did not respond to androgens. Concentrations of testosterone and the synthetic androgen, R1881, between 1-1000 pM induced transient calcium increases with ED(50) values near 1 pM and 1 nM, whereas dihydrotestosterone (DHT) was not active at these concentrations. At concentrations higher than 1 nM, testosterone, R1881, and DHT were equipotent in stimulating an increase in calcium that lasted for more than 10 min, with ED(50) values between 5 and 20 nM. Testosterone covalently bound to albumin was also active, whereas 11 related androstane compounds as well as progesterone and estradiol-17beta were inactive at 1000 nM. The calcium response induced by the three androgens (10 nM) was abolished in all cell types by hydroxyflutamide (1000 nM) and finasteride (1000 nM), but not by cyproterone acetate (1000 nM). The calcium response was also abolished in the absence of extracellular calcium and strongly inhibited by the presence of verapamil. Exposure of the responsive cells to brief (150-sec) pulses of androgens generated calcium responses that were similar to those after continuous exposure. After exposure of Sertoli cells for only 30 sec to 100 nM testosterone, the calcium response lasted for at least 50 min. Although nuclear binding of androgens could be demonstrated, there was no evidence for tight binding to the plasma membrane under similar conditions. When protein synthesis was inhibited, an enhancement of GJIC between rat Sertoli cells, but not between LNCaP cells or PC3 cells, was observed within 15 min of the addition of 10 nM testosterone. Because nuclear androgens are not present in PC3 cells and many functional properties of the responsive system are different from the nuclear receptor in all three cell types, we postulate the existence of an alternative cell surface receptor system with biphasic response characteristics (high and low affinity). The calcium signals are probably coupled to the regulation of gap junctional efficiency between Sertoli cells. The low-affinity receptors may convey complementary androgen signals at elevated local levels such as in the testis, when nuclear receptors are (over)saturated.

Real-time studies of the interactions between epidermal growth factor and its receptor during endocytic trafficking

The interactions of growth factors with cell surface receptors regulate fundamental cell processes, such as growth, differentiation and transformation. Understanding the nature of these interactions at the molecular level is of fundamental importance in cell biology. This is not only from the point of view of basic science, but also because of the repercussions such knowledge might have in understanding the mode of action of drugs in cells. Receptor mediated endocytosis has been implicated in the downregulation of the mitogenic signal. However, no data are thus far available on how growth factor/receptor interactions might control endocytic trafficking. Here we show that information on modes of binding and receptor conformational changes can be obtained using time-resolved fluorescence methods. We have found that fluorescent probes bound to epidermal growth factor (EGF) show dynamic fluorescence quenching when EGF is bound to internalising EGF receptors (EGFR). We propose that this dynamic quenching takes place because EGF-bound probes interact with tryptophan residues in the extracellular domain of the EGF-EGFR complex. Real-time accumulation of fluorescent decays has also allowed us to follow the time course of a conformational change in EGFR occurring during endocytosis, and correlate this information with endosomal trafficking and EGFR recycling.

Optimisation of procedures for the extraction of structural analogues of propranolol with molecular imprinted polymers for sample preparation

A propranolol-derived molecular imprinted polymer (MIP) was prepared using methacrylic acid as monomer and ethylene glycol dimethacrylate as cross-linker. The extraction properties of five compounds structurally related to propranolol were assessed on the MIP and on a blank polymer made under the same conditions but in the absence of an imprint molecule. Using application from aqueous solution with methanol-water-triethylamine (TEA)-based solvents for elution (i.e. reversed-phase conditions) the MIP showed only marginal selectivity for the compounds on the MIP compared to the blank. Despite the limited selectivity there did appear to be a relationship between structure of the compound (relative to propranolol) and the extent of selective retention. Application of the compounds in toluene with elution using toluene-TEA or toluene-trifluoroacetic acid resulted in the MIP showing dramatically enhanced retention and selectivity of the compounds on the MIP compared to the blank. The enhanced selectivity for extraction on to the MIP relative to the blank, for all compounds using normal-phase solvents seem to be a class effect as there was no apparent relationship between compound structure and retention.

Synchrotron X-ray investigations into the lamellar gel phase formed in pharmaceutical creams prepared with cetrimide and fatty alcohols

Semisolid liquid paraffin-in-water emulsions (aqueous creams) prepared from cetrimide/fatty alcohol mixed emulsifiers, and ternary systems formed by dispersing the mixed emulsifier in controlled percentages of water were examined as they aged using a combination of low and high angle X-ray diffraction measurements (Daresbury Laboratory Synchrotron Radiation Source). The results were correlated with the rheological properties measured in earlier studies. The cationic emulsifying wax showed phenomenal swelling in water. The reflection that incorporates interlamellar water increased continuously from 74 A at 28% water to over 500 A at 93% water. The trend was not influenced by the method of incorporation of the components and swollen lamellar phase was also identified in the corresponding emulsion. The swelling, which was due to electrostatic repulsion, was suppressed by salt and was reduced when the surfactant counterion was changed from Br(-) to Cl(-). Changes in rheological properties on storage and in the presence of salt were correlated with changes in water layer thickness. High angle diffraction confirmed that the hydrocarbon bilayers were in the hexagonal alpha-crystalline mode of packing. Ternary systems and creams prepared from pure alcohols, although initially semisolid, were rheologically unstable and broke down. Low angle X-ray study into the kinetics of structure breakdown showed that the swollen lamellar gel phase formed initially swells even further on storage before separating.

Use of Dufour's gland secretion in nest defence and brood nutrition by hover wasps (Hymenoptera, Stenogastrinae)

Social wasps of the subfamily Stenogastrinae produce an abdominal secretion that is used in two distinct biological contexts. First, the secretion plays an important role in larval nutrition where it serves as a substrate in which food is placed by the adults for eventual consumption by the larvae. Second, in several species, females apply the same secretion to the substrate on which their nests are constructed, where it constitutes a sticky barrier that defends the immature brood from predation by ants. This paper describes for the first time ant guard construction behaviour of three species of stenogastrine wasps belonging to the genera Eustenogaster and Liostenogaster. The identification of compounds making up these secretions was also performed by gas chromatography-mass spectrometry. Ant guards and brood secretions were similar, with saturated and unsaturated long chain hydrocarbons and alcohols as major components. We further confirm that the glandular source of abdominal secretion is the Dufour's gland. This gland contains the same hydrocarbons, and in the same proportions as ant guards and brood secretion. We discuss the fundamental importance of Dufour's gland secretion in the social life of these wasps by comparing species with and without ant guards within the subfamily.

Justification of pulse oximeter costs for paramedic prehospital providers

OBJECTIVE

To assess the potential cost savings of decreasing prehospital oxygen utilization by using pulse oximetry to identify those patients who do not require supplemental oxygen.

METHODS

A prospective, controlled trial was performed comparing rates of oxygen utilization by paramedics with and without access to pulse oximetry. Consecutive patient encounters over a ten-week period were randomized by day of presentation. Pulse oximeters were made available on alternate days. On those days, patients whose oxygen saturations were less than 95% were treated with supplemental oxygen.

RESULTS

The use of pulse oximeters incurred a saving of 0.14 "D"-size oxygen cylinders per call. For the authors' service, this translates to a potential saving of $2,324 (C)/vehicle/year.

CONCLUSION

For regions with patient demographics similar to the authors', the initial cost of providing paramedics with pulse oximeters may be offset by savings in oxygen consumption. A formula is provided to allow individual ambulance services to calculate the potential savings for their service.

Lack of immunity in university students before an outbreak of serogroup C meningococcal infection

Immunity to meningococci was determined in infected and uninfected students before and during an outbreak of serogroup C meningococcal infection at a university in the United Kingdom. No immunity against the outbreak strain was detected in serum taken from infected students prior to the outbreak or at the time of admission; bactericidal activity developed during convalescence. Carriage of all strains of serogroup C meningococci in asymptomatic students was low (0.9%), and no carriage of the outbreak strain could be detected. Immunity in the at-risk student population before the outbreak was low: 90% of students had no significant bactericidal activity against the outbreak strain. A low prevalence of carriage of the outbreak strain, together with a low prevalence of protective immunity within the student population, was associated with a high incidence of invasive disease in those who acquired the outbreak strain.

Selective pressure as an essential force in molecular evolution of myeloid leukemic clones: a view from the window of Fanconi anemia

Specific chromosomal deletions are commonly found in bone marrow cells of children with Fanconi anemia (FA) whose disease has evolved to myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Identical deletions are found in adults with MDS/AML with a history of exposure to alkylating agents (secondary MDS/AML). While deleted chromosomal regions likely harbor genes encoding proteins with tumor suppressor (TS) function, such genes have not been identified and the environmental forces by which these mutant clones are selected remain unclear. A consistent signaling abnormality in cells bearing mutations of the Fanconi anemia complementation group C (FA-C) gene (FANCC) has revealed a potential selective force. Hematopoietic progenitor cells from patients and mice with FANCC mutations are hypersensitive to the inhibitory effects of IFNgamma and TNFalpha. Consequently, clonal outgrowths in FA likely result from strong selective pressure for stem and/or progenitor cells resistant to these inhibitory cytokines. Additional mutations that inactivate signaling pathways for these inhibitors would create a cell with a profound proliferative advantage over its apoptosis-prone counterparts. Here, we present preliminary evidence supporting a selection-based model of leukemic evolution and argue that MDS in FA patients is a de facto model of secondary MDS in non-FA adults.

Extended circular dichroism measurements using synchrotron radiation show that the assembly of clathrin coats requires no change in secondary structure

A number of models have been proposed for the assembly of clathrin triskelia into coats. However, little is known of the effects of assembly on triskelion structure. A more detailed knowledge of the way in which assembly affects triskelion structure would be valuable for assessing the relative merits of the proposed models. The development of a vacuum-ultraviolet circular dichroism (CD) instrument that uses synchrotron radiation as a light source has allowed us to extend the range of CD measurements to shorter wavelengths. This has greatly increased signal quality even for highly scattering samples. Also, we have improved CD data analysis to provide standard deviations for calculated secondary structure content. These developments have increased the precision of CD analysis beyond what has been thus far possible. Using these developments, we have determined the secondary structure content of all components of coat protein, under both assembly and dissociating conditions. The assembly of coats does not incur any change in secondary structure content, but a 10% loss of triskelion helical content accompanies assembly in the absence of AP-2. We conclude that coat assembly requires no detectable reorganization of triskelion structure. Our result indicates that AP-2 stabilizes helical structure in the triskelion, and we propose that this increases triskelion rigidity, restricting the range of coat sizes.

The alpha-helix folds on the millisecond time scale

It has long been believed that nucleation of the alpha-helix is a very fast reaction, occurring in around 10(-7) s. We show here that helix nucleation, in fact, takes place on the millisecond time scale. The rate of alpha-helix nucleation in two polyalanine-based peptides and in lysine and glutamic acid homopolymers was measured directly by stopped-flow deep UV CD with synchrotron radiation as the light source. Synchrotron radiation CD gives far superior signal to noise than a conventional instrument. The 16-aa AK peptide folds with first-order kinetics and a rate constant of 15 s-1 at 0 degrees C. The rate-determining step is presumably the initiation of a new helix, which occurs at least 10(5) times slower than expected. Helix folding occurs in at least two steps on the millisecond time scale for the longer peptides, with a transient overshoot of helix content significantly greater than at equilibrium, similar to that seen in the folding of several proteins. We suggest that the overshoot is caused by the formation of a single long helix followed by its breakage into the two or more helices present at equilibrium.

Iron in the basal ganglia in Parkinson's disease. An in vitro study using extended X-ray absorption fine structure and cryo-electron microscopy

Iron is found in high concentration in some areas of the brain, and increased iron in the substantia nigra is a feature of Parkinson's disease. The purpose of this study was to investigate the physical environment of brain iron in post-mortem tissue to provide information on the possible role of iron in neurodegeneration in Parkinson's disease. Iron has also been implicated as the cause of signal loss in areas of high brain iron on T2-weighted MRI sequences. Knowledge of the physical environment of the brain iron is essential in interpreting the cause of signal change. Post-mortem tissue was obtained from six cases of Parkinson's disease and from six age-matched controls. Iron levels were measured using absorption spectrophotometry. Extended X-ray absorption fine structure was used to evaluate the atomic environment of iron within the substantia nigra and both segments of the globus pallidus. Cryo-electron transmission microscopy was used to probe the iron storage proteins in these areas. Iron levels were increased in the parkinsonian nigra and lateral portion of the globus pallidus. Spectra from the extended X-ray absorption fine structure experiments showed that ferritin was the only storage protein detectable in both control and parkinsonian tissue in all areas studied. Cryo-electron transmission microscopy studies showed that ferritin was more heavily loaded with iron in Parkinson's disease when compared with age-matched controls. In summary we have shown that iron levels are increased in two areas of the brain in Parkinson's disease including the substantia nigra, the site of maximal neurodegeneration. This produces increased loading of ferritin, which is the normal brain iron storage protein. It is possible that increased loading of ferritin may increase the risk of free radical-induced damage. Differences in ferritin loading may explain regional differences in iron's effect on the T2 signal.

A practical guide to evaluation and treatment of infections in patients with central venous catheters

Infection in patients with central venous catheters can be a serious complication leading to costly disruption of their ongoing medical needs. A systematic, algorithm-based approach to evaluation and treatment of infections in this very diverse population is presented and emphasizes rapid and thorough determination of infection sources and outlines decisions regarding use of antibiotic therapy. Catheter-related infections, including bacteremia and exit site, tunnel, and pocket infections, can be treated in many cases without removal of the device. Recently developed treatment protocols and new technologies devised to decrease infection risk and improve outcome are discussed.

Dynamics of carriage of Neisseria meningitidis in a group of military recruits: subtype stability and specificity of the immune response following colonization

Meningococcal carriage and the immune response to colonization were studied in a group of military recruits undergoing basic training. Subtyping by determination of the class 1 protein sequence clearly differentiated between strains and demonstrated the dynamics of carriage and transmission. Expression of class 1 protein by each strain remained stable during prolonged carriage by different subjects. Following colonization, a marked increase in serum bactericidal response occurred, which was specific for the subtype of the acquired strain and was associated with an increase in reactivity by Western blot to the homologous class 1 protein. Subjects colonized by multiple strains showed evidence of a specific immune response to the class 1 protein of each strain acquired. The subtype specificity of the bactericidal response to meningococci and the stability of expression of the class 1 protein have important implications for the design of vaccines for prevention of serogroup B meningococcal disease.

The Ontario Prehospital Advanced Life Support (OPALS) Study: rationale and methodology for cardiac arrest patients

The Ontario Prehospital Advanced Life Support Study represents the largest prehospital study yet conducted, worldwide. This study will involve more than 25,000 cardiac arrest, trauma, and critically ill patients over an 8-year period. The study will evaluate the incremental benefit of rapid defibrillation and prehospital Advanced Cardiac Life Support measures for cardiac arrest survival and the benefit of Advanced Life Support for patients with traumatic injuries and other critically ill prehospital patients. This article describes the OPALS study with regard to the rationale and methodology for cardiac arrest patients.

Assessment criteria in identifying the sick sepsis patient

Standard definitions of sepsis have been proposed and have been widely adopted. Recognition of the systemic inflammatory response syndrome (SIRS) and assessment of its severity can easily be achieved at the bedside using basic observations and simple laboratory tests. Fulfillment of standardized criteria defining increasing severity of sepsis or manifestation of two, three and four SIRS criteria directly correlates with risk of mortality and progression to organ failure. However, manifestation of only two SIRS criteria identifies patients who may have relatively mild disease. Furthermore, sepsis definitions take no account of pre-existing illness, source of infection or causative agent, all of which have a significant influence on outcome. Despite these limitations, manifestation of four SIRS criteria or the persistence of markers of severe sepsis identifies individuals on general wards who are at particularly high risk of death, who should be closely monitored for deterioration and discussed with an intensive-care physician at an early stage. If the source of sepsis is not clear, empirical antibiotic therapy for such individuals should be discussed with a medical microbiologist or infectious diseases physician.

An uncommon fatality due to moclobemide and paroxetine

A young man was found shivering and incoherent at home. He was placed in bed and was observed having seizures some time later. About four hours after he was initially found, he suffered a full cardiac arrest. Paramedics found his jaw unusually stiff and were unable to open his mouth in order to intubate him. Resuscitation attempts were unsuccessful. The autopsy findings were unremarkable, but toxicology testing revealed the following: moclobemide (subclavian blood, 18.5 mg/L; liver, 28.5 mg/kg; gastric contents, 77 mg/69 g) and paroxetine (subclavian blood, 1.58 mg/L; liver, 15.3 mg/kg; gastric contents, 0.7 mg/69 g). The cause of death was attributed to the combined toxicity of moclobemide and paroxetine. Deaths attributed primarily to these drugs are extremely rare because both are considerably less toxic than older monoamine oxidase and tricyclic antidepressant drugs. Based on the history of the case and pharmacology of the drugs involved, the most likely mechanism of death was severe "serotonin syndrome" resulting from the overdose.

Very unusual ethanol distribution in a fatality

A 48-year-old man with an extensive history of alcoholism was found dead at home. He was lying face down on a carpet. There was evidence of gastric aspiration at autopsy and histologic examination. The distribution of ethanol was very unusual (concentrations in mg/100 mL or mg/100 g): femoral blood, 257 and 273 (two samples); heart blood, 643; vitreous humor, 763; urine, 84; bile, 616; liver, 250; and gastric, 4660 (2470 mg/53 g). In addition, this man ingested isopropanol, and, according to the history, may also have ingested acetone in the form of nail polish remover. The distribution of both isopropanol and acetone was as expected, which was approximately in proportion to the aqueous content of the respective tissues. It is proposed that agonal or postmortem aspiration of the ethanol-rich vomitus and postmortem fermentation could account for the apparently elevated concentrations of ethanol in heart blood and bile. The elevated vitreous ethanol could be explained if ethanol diffused across the eye in the agonal phase or postmortem from gastric aspirate in the carpet. The relatively low urinary ethanol concentration would be consistent with a recent binge-drinking episode, which allowed only a limited time period for excretion into an already partially full, but relatively ethanol-free, bladder.