Evidence of trade-offs shaping virulence evolution in an emerging wildlife pathogen.

In the mid-1990s, the common poultry pathogen Mycoplasma gallisepticum (MG) made a successful species jump to the eastern North American house finch Haemorhous mexicanus (HM). Subsequent strain diversification allows us to directly quantify, in an experimental setting, the transmission dynamics of three sequentially emergent geographic isolates of MG, which differ in the levels of pathogen load they induce. We find significant among-strain variation in rates of transmission as well as recovery. Pathogen strains also differ in their induction of host morbidity, measured as the severity of eye lesions due to infection. Relationships between pathogen traits are also investigated, with transmission and recovery rates being significantly negatively correlated, whereas transmission and virulence, measured as average eye lesion score over the course of infection, are positively correlated. By quantifying these disease-relevant parameters and their relationships, we provide the first analysis of the trade-offs that shape the evolution of this important emerging pathogen.

Genomancy: predicting tumour response to cancer therapy based on the oracle of genetics.

Cells are complex systems that regulate a multitude of biologic pathways involving a diverse array of molecules. Cancer can develop when these pathways become deregulated as a result of mutations in the genes coding for these proteins or of epigenetic changes that affect gene expression, or both1,2. The diversity and interconnectedness of these pathways and their molecular components implies that a variety of mutations may lead to tumorigenic cellular deregulation3-6. This variety, combined with the requirement to overcome multiple anticancer defence mechanisms7, contributes to the heterogeneous nature of cancer. Consequently, tumours with similar histology may vary in their underlying molecular circuitry8-10, with resultant differences in biologic behaviour, manifested in proliferation rate, invasiveness, metastatic potential, and unfortunately, response to cytotoxic therapy. Thus, cancer can be thought of as a family of related tumour subtypes, highlighting the need for individualized prediction both of disease progression and of treatment response, based on the molecular characteristics of the tumour.

Note: A miniature oscillating microbalance for sampling ice and volcanic ash from a small airborne platform.

A lightweight and low power oscillating microbalance for in situ sampling of atmospheric ice and volcanic ash is described for airborne platforms. Using a freely exposed collecting wire fixed at only one end to a piezo transducer, the instrument collects airborne materials. Accumulated mass is determined from the change in natural frequency of the wire. The piezo transducer is used in a dual mode to both drive and detect the oscillation. Three independent frequency measurement techniques are implemented with an on-board microcontroller: a frequency sweep, a Fourier spectral method, and a phase-locked loop. These showed agreement to ±0.3 Hz for a 0.5 mm diameter collecting wire of 120 mm long, flown to 19 km altitude on a weather balloon. The instrument is well suited to disposable use with meteorological radiosondes, to provide high resolution vertical profiles of mass concentration.

Effects of cis-diamminedichloroplatinum(II) on rabbit kidney in vivo and on rabbit renal proximal tubule cells in culture.

The nephrotoxic potential of cis-diamminedichloroplatinum(II) (CDDP) in rabbits, as well as its effect on cell viability, cellular synthetic activity, and specific enzyme activities in rabbit renal proximal tubule cells, was investigated. Male New Zealand White rabbits were given a single i.v. dose of either 2.5 or 5.0 mg/kg CDDP via the ear vein and sacrificed 5 days later. No drug-induced changes were observed in the kidneys of rabbits given 2.5 mg/kg CDDP. However, histopathological examination of kidneys from rabbits administered 5.0 mg/kg CDDP revealed marked tubular degeneration and necrosis, with the majority of lesions being situated in the outer zone of the cortex. This is in contrast to the effect of CDDP in the kidney of the rat where the necrosis is reported to be predominantly localized to the pars recta of the proximal tubule in the outer stripe of the medulla. The results from the in vitro experiments indicated that the viability of cells after a 6-h exposure to CDDP at concentrations up to 100 microM was greater than 95%. However, a dose-dependent decrease in cell viability was obtained after 24 h exposure with a TD50 (50% viability) of approximately 90 microM. In addition, the results after 24 h exposure to CDDP also indicated that Na+, K+-ATPase, a basolateral membrane marker enzyme, and alkaline phosphatase, a brush-border marker enzyme, were inhibited by 35-40% and 20%, respectively. No effect on succinic dehydrogenase, a mitochondrial marker enzyme, was obtained. Inhibition of all three marker enzymes was minimal at 6 h posttreatment. On the other hand, inhibition of DNA, RNA, and protein syntheses was evident as early as 6 h posttreatment with DNA (48-77%) and RNA (36-77%) syntheses being inhibited to a greater extent than protein synthesis (14-33%). These results demonstrate that inhibition of renal synthetic activity by CDDP, rather than its effect on enzyme activity, precedes the onset of cell lethality and may therefore be an important event in the initiation of CDDP-induced nephrotoxicity.

On the detection and attribution of gravity waves generated by the 20 March 2015 solar eclipse.

Internal gravity waves are generated as adjustment radiation whenever a sudden change in forcing causes the atmosphere to depart from its large-scale balanced state. Such a forcing anomaly occurs during a solar eclipse, when the Moon's shadow cools part of the Earth's surface. The resulting atmospheric gravity waves are associated with pressure and temperature perturbations, which in principle are detectable both at the surface and aloft. In this study, surface pressure and temperature data from two UK sites at Reading and Lerwick are examined for eclipse-driven gravity wave perturbations during the 20 March 2015 solar eclipse over northwest Europe. Radiosonde wind data from the same two sites are also analysed using a moving parcel analysis method, to determine the periodicities of the waves aloft. On this occasion, the perturbations both at the surface and aloft are found not to be confidently attributable to eclipse-driven gravity waves. We conclude that the complex synoptic weather conditions over the UK at the time of this particular eclipse helped to mask any eclipse-driven gravity waves.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'.

Coordinated weather balloon solar radiation measurements during a solar eclipse.

Solar eclipses provide a rapidly changing solar radiation environment. These changes can be studied using simple photodiode sensors, if the radiation reaching the sensors is unaffected by cloud. Transporting the sensors aloft using standard meteorological instrument packages modified to carry extra sensors, provides one promising but hitherto unexploited possibility for making solar eclipse radiation measurements. For the 20 March 2015 solar eclipse, a coordinated campaign of balloon-carried solar radiation measurements was undertaken from Reading (51.44°N, 0.94°W), Lerwick (60.15°N, 1.13°W) and Reykjavik (64.13°N, 21.90°W), straddling the path of the eclipse. The balloons reached sufficient altitude at the eclipse time for eclipse-induced variations in solar radiation and solar limb darkening to be measured above cloud. Because the sensor platforms were free to swing, techniques have been evaluated to correct the measurements for their changing orientation. In the swing-averaged technique, the mean value across a set of swings was used to approximate the radiation falling on a horizontal surface; in the swing-maximum technique, the direct beam was estimated by assuming that the maximum solar radiation during a swing occurs when the photodiode sensing surface becomes normal to the direction of the solar beam. Both approaches, essentially independent, give values that agree with theoretical expectations for the eclipse-induced radiation changes.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'.

Genetic influences on plasma catecholamines in human twins.

We examined the relative genetic and environmental influences on the variability in plasma epinephrine, norepinephrine, and dopamine levels in 109 twin pairs. Epinephrine levels were lower in females (P = 0.048). The norepinephrine concentration increased with age (r = 0.40; P < 0.001). Blood pressure (BP) was not associated with epinephrine levels in either sex or with norepinephrine levels in females. In males, there was a positive association between norepinephrine concentration and diastolic BP (r = 0.31; P = 0.020). A negative association between dopamine levels and systolic and diastolic BP in females (r = -0.22; P = 0.014 and r = -0.20; P = 0.027, respectively) was not maintained after accounting for age, body mass index, and sex. Using path analysis and maximum likelihood model fitting, genetic, unique environment, and age effects contributed 57% (P < or = 0.001), 27% (P < or = 0.001), and 16% (P < or = 0.001) to the variability in norepinephrine, respectively. Genetic effects explained 64% (P < 0.1) and 74% (P < 0.1) of the variability in epinephrine concentrations in females and males, respectively. Unique environmental influences explained the remainder. Genetic and unique environmental effects explained 72% (P < 0.01) and 28% (P < or = 0.001) of the variability in dopamine levels. These results indicate a substantial genetic influence on plasma catecholamine levels. Although consistent associations between plasma catecholamines and BP were not evident in this study, the observed genetic influence on circulating catecholamines may be relevant to the potential role of the sympathetic nervous system in the early stages of essential hypertension.

Genetic and environmental covariance of serum cholesterol and blood pressure in female twins.

Blood pressure elevation is frequently associated with elevated cholesterol, triglyceride or low density lipoprotein (LDL-C) or low high density lipoprotein (HDL-C). The relative importance of genetic and environmental factors in these associations is unclear. We examined the relative contribution of genetic and environmental influences to the association between blood pressure and serum lipids in 75 pairs of female twins using path analysis and maximum-likelihood model fitting. Associations between systolic blood pressure and total cholesterol (r = 0.44, P < 0.001), and LDL-C (r = 0.38, P < 0.001), but not HDL-C (r = 0.05, N.S.), remained significant after age and body mass index adjustment. Univariate models suggested genetic effects contributed 60-70% to the variance of total cholesterol, LDL-C, HDL-C and systolic blood pressure. The remaining variance was explained by age and/or unique environmental influences. Using bivariate models, we demonstrated genetic (P = 0.017) and unique environmental covariance (P = 0.011) of cholesterol and systolic blood pressure. Significant genetic covariance (P = 0.038) was observed between LDL-C and systolic blood pressure. The association between blood pressure and total cholesterol in these twins results from shared genetic and similar unique environmental influences. The association between LDL-C and blood pressure is partly due to shared genetic influences. We conclude that both additive genetic and environmental factors unique to the individual are important determinants of the relationships between serum lipids and blood pressure.

Renin inhibitors containing conformationally restricted P1-P1' dipeptide mimetics.

A series of renin inhibitors containing lactam-bridged P1-P1' dipeptide mimetics based on the ACHPA (4(S)-amino-5-cyclohexyl-3(S)-hydroxypentanoic acid) design was studied. The inhibitors were obtained by aldol addition of various lactams with N alpha-Boc-L-cyclohexylalaninal, followed by Boc group removal and acylation with Boc-Phe-His. The aldol diastereomer having the S configuration at the two newly generated stereogenic centers gave optimal enzyme inhibition. Potency was further enhanced in the gamma-lactam ring series by substitution with small hydrophobic groups to mimic the P1' side chain of the renin substrate. Thus, 2(S)-[(Boc-L-phenylalanyl-L-histidyl)amino]-3-cyclohexyl-1(S)-hydroxyl-1 - (1,5,5-trimethyl-2-oxopyrrolidin-3(S)-yl)propane (34) has an IC50 of 1.3 nM in the human plasma renin assay. A variety of substituents on the lactam nitrogen are tolerated and can be used to vary the physical properties of the inhibitor. By using a model of the human renin active site, the conformation of 34 in the enzyme-inhibitor complex is proposed. This modeled conformation is very similar to the solid-state conformation of 2(S)-[(Boc-L-phenylalanyl-L-histidyl)amino]-3-cyclohexyl-1(S)-hydroxyl- 1-(1-methyl-2-oxopyrrolidin-3(S)-yl)propane (36), the structure of which was determined by single-crystal X-ray diffraction analysis. The most potent ACH-PA-lactam renin inhibitors show good selectivity when assayed against other types of aspartic proteinases. By varying the lactam ring substituents, potent and selective inhibitors of cathepsin D and cathepsin E can be obtained.

Nanomolar-affinity, non-peptide oxytocin receptor antagonists.

Non-peptide antagonists of the peptide hormone oxytocin (OT) with nanomolar OT receptor affinities are described. These compounds incorporate novel amido- and amidoalkylcamphor variations to the lead structure L-366,509 (1) to achieve receptor affinity enhancements of 2-3 orders of magnitude over that compound. The new OT antagonist L-367,773 (35) is shown to be an orally bioavailable agent with good duration in vivo and to inhibit OT-stimulated uterine contractions effectively in several in vitro and in vivo models.

Development of a novel class of cyclic hexapeptide oxytocin antagonists based on a natural product.

A new structural class of cyclic hexapeptide oxytocin antagonists derived from Streptomyces silvensis and typified by L-365,209 (cyclo-[L-prolyl1-D-phenylalanyl2-L- isoleucyl3-D-dehydropiperazyl4-L-dehydroperazyl5-D-(N- methyl)phenylalanyl6]) was recently reported. In this paper we further delineate the structure-activity profile for this new class by systematic study of L-365,209 analogs obtained by total synthesis. The optimal combination of cyclic amino acid ring sizes at positions 1, 4, and 5 and the role of the N-alkyl substituent at position 6 was elucidated. The lipophilic amino acids at positions 2 and 3 and the unusual amino acid D-dehydropiperazic acid at position 4 were found to be the most critical residues for obtaining good oxytocin receptor affinity. Analogs containing a basic side chain at the less critical 5- and 6-positions maintained good receptor affinity and also had useful levels of water solubility for intravenous formulation. By combining potency- and solubility-enhancing substitutions, several analogs were identified that have the desired combination of properties in vitro (22, cyclo-[L-prolyl-D-tryptophanyl-L-isoleucyl-D-pipecolyl-L-pipeco lyl-D- histidyl]; 25, cyclo-[L-prolyl-D-2-naphthylalanyl-L-isoleucyl-D-pipecolyl-L -pipecolyl-D- histidyl]; 26, cyclo-[L-prolyl-D-tryptophanyl-L-isoleucyl-D-dehydropiperazyl-L-++ pipecolyl-D-histidyl]; 33, cyclo-[L-prolyl-D-tryptophanyl-L-isoleucyl-D-pipecolyl-L- piperazinylcarboxy-D-(N-methyl)phenylalanyl]; 34, cyclo-[L-prolyl-D-phenylalanyl-L-isoleucyl-D-dehydropiperazyl-L-or nithyl- D-(N-methyl)phenylalanyl]). In general, this class exhibited good selectivity for binding to the oxytocin receptor versus the arginine vasopressin V1a and V2 receptor subtypes, although increased V2 receptor affinity was observed in one case (32, cyclo[L-prolyl-D-2-naphthylalanyl-L-isoleucyl-D-pipecolyl-L- lysyl-D-(N- methyl)phenylalanyl]). Unexpectedly, compound 33 was found to stimulate contractions of the isolated rat uterus via activation of the uterine bradykinin receptor. Compounds 22, 25, 26, 33, and 34 were found to be potent antagonists of oxytocin-stimulated contraction of the rat uterus in vitro and in vivo. Compounds 22 and 25 were additionally characterized as potent antagonists of oxytocin-stimulated uterine contractions in the near-term pregnant rhesus monkey. These studies thus demonstrate the selectivity and efficacy of certain members of this novel class of antagonists and suggest their use as pharmacological tools in further defining the role of oxytocin in both term and preterm labor.

1-((7,7-Dimethyl-2(S)-(2(S)-amino-4-(methylsulfonyl)butyramido)bicyclo [2.2.1]-heptan-1(S)-yl)methyl)sulfonyl)-4-(2-methylphenyl)piperaz ine (L-368,899): an orally bioavailable, non-peptide oxytocin antagonist with potential utility for managing preterm labor.

Modifications to the previously reported spiroindenylpiperidine camphor-sulfonamide oxytocin (OT) antagonist L-366,509 have produced a new series of o-tolylpiperazine (TP) camphor-sulfonamides. A number of analogues in the TP series that incorporate a modified or unmodified L-methionine sulfone amide at the C2 endo position on the camphor ring exhibit high affinity for OT receptors (IC50 = 1.3-15 nM) and good selectivity for binding to OT versus arginine vasopressin V1a and V2 receptors. Several of these analogues were additionally characterized as potent antagonists of OT-stimulated contractions of the isolated and/or in situ rat uterus. Compound 7 (L-368,899) exhibited the best overall profile of OT receptor affinity (IC50 = 8.9 nM, rat uterus; 26 nM, human uterus), potency for inhibition of OT-stimulated contractions of the isolated rat uterus (pA2 = 8.9) and in situ rat uterus (AD50 = 0.35 mg/kg after intravenous (i.v.) administration and 7.0 mg/kg after intraduodenal administration), aqueous solubility (3.7 mg/mL at pH 5.0), and oral bioavailability in several species (35% (rat), 25% (dog), and 21% (chimpanzee) as estimated from radioreceptor determination of drug levels in plasma after oral and i.v. dosing). On the basis of these favorable properties, 7 has begun clinical testing for use as an oral and i.v. tocolytic agent. Molecular modeling alignment studies have provided support for the hypothesis that the TP camphor-sulfonamide portion of the non-peptide structures may serve as a mimetic of the important D-AA2-Ile3 dipeptide (AA = aromatic amino acid) found in many potent OT antagonists from the cyclic hexapeptide and OT analogue structural classes.

Development of orally active oxytocin antagonists: studies on 1-(1-[4-[1-(2-methyl-1-oxidopyridin-3-ylmethyl)piperidin-4-yloxy]-2- methoxybenzoyl]piperidin-4-yl)-1,4-dihydrobenz[d][1,3]oxazin-2-one (L-372,662) and related pyridines.

The previously reported oxytocin antagonist L-371,257 (2) has been modified at its acetylpiperidine terminus to incorporate various pyridine N-oxide groups. This modification has led to the identification of compounds with improved pharmacokinetics and excellent oral bioavailability. The pyridine N-oxide series is exemplified by L-372,662 (30), which possessed good potency in vitro (Ki = 4.1 nM, cloned human oxytocin receptor) and in vivo (intravenous AD50 = 0.71 mg/kg in the rat), excellent oral bioavailability (90% in the rat, 96% in the dog), good aqueous solubility (>8.5 mg/mL at pH 5.2) which should facilitate formulation for iv administration, and excellent selectivity against the human arginine vasopressin receptors. Incorporation of a 5-fluoro substituent on the central benzoyl ring of this class of oxytocin antagonists enhanced in vitro and in vivo potency but was detrimental to the pharmacokinetic profiles of these compounds. Although lipophilic substitution around the pyridine ring of compound 30 gave higher affinity in vitro, such substituents were a metabolic liability and caused shortfalls in vivo. Two approaches to prevent this metabolism, addition of a cyclic constraint and incorporation of trifluoromethyl groups, were examined. The former approach was ineffective because of metabolic hydroxylation on the constrained ring system, whereas the latter showed improvement in plasma pharmacokinetics in some cases.

Interactions between sources of mortality and the evolution of parasite virulence.

A well-known result from the theory of the evolution of virulence is the prediction that the virulence of a pathogen (i.e. the rate of parasite-induced host mortality) always evolves to higher levels when host background mortality rates increase. This prediction, however, is derived from models that assume that host mortality sources combine additively to determine the overall host mortality rate. In this paper, we suggest that such additivity is probably rare for many host-pathogen systems, and explore how the predictions for the evolution of virulence are altered when interactions between host mortality sources are incorporated into the theory. Our results indicate that if mortality-source interactions are sufficiently strong then the evolutionarily stable level of virulence can actually decrease as the background mortality rate increases. Consequently, a detailed mechanistic description of how parasites and other mortality sources combine to cause host mortality is required before reliable predictions about virulence evolution can be made. Moreover, mortality-source interactions make empirical comparisons of the virulence of different parasites a much more subtle issue.

A new class of simplified phorbol ester analogues: synthesis and binding to PKC and eta PKC-C1B (eta PKC-CRD2).

[formula: see text] A unique class of simplified phorbol ester analogues is described for the first time. A highly efficient retro-annelation sequence was developed in order to remove the five-membered ring from the phorbol diterpene core, allowing access to BCD ring analogues of the phorbol esters. The binding of these analogues to protein kinase C (PKC) and the truncated peptide eta PKC-C1B (eta PKC-CRD2) is also reported.

Beneficial effects of adriamycin on Wistar-Furth Wilms' tumor.

The Wilms' tumor (Wistar-Furth, Columbia University) animal model kills the host in a predictable period of time, associated with widespread metastases (lungs, liver, spleen) regardless of the route of tumor transplantation. Actinomycin D in single or multiple doses has previously been shown to increase survival, reduce the primary tumor weight, as well as the number of metastases in this experimental model. The model thus has close similarity to man. The present report describes a remarkable effect of adriamycin in this animal system. The beneficial results are, however, limited by severe dose-related toxicity. Nevertheless, faced with recurrent or metastatic lesions following prior current conventional clinical therapy, based on the present experimental results, we believe adriamycin treatment should be given serious clinical consideration.

Experimental bladder tumor induction, propagation, and therapy.

The development of animal bladder tumor models as a research tool for different modes of therapy has been widely evaluated. Recently these tumors have either spontaneously grown or have been propagated in inbred strains. Bladder tumors have also been chemically produced by N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) when orally administered over a long period of time. It has been further reported that these tumors have been inhibited by various chemotherapy regimens. The availability of an experimental bladder tumor model offers an opportunity to evaluate the effectiveness of a prescribed treatment. In our studies FANFT was noted to produce only from 33 to 40% bladder tumors in several experiments in an inbred strain of rats conducted over several years. Reproducible transplantability of these tumors was not demonstrable in the same inbred strain. In addition, treatment with mitomycin C an an effective chemotherapeutic agent was not detectable in part, since comparably the percentage of control bladder tumor growth was low. These findings of a three-year study should be carefully considered when evaluating recommendations for clinical adjuvant chemotherapy based on results obtained with FANFT.

Clinical significance of erythropoietin levels in renal carcinoma.

The bioassay using the polythemic mice demonstrated persistent erythropoietin (Ep) activity in 24 renal carcinoma patients. Eight patients without clinical evidence of renal carcinoma had Ep levels that were slightly higher than those of controls, suggesting the possibility of occult disease. Increased levels of Ep were noted in 5 patients with other genitourinary carcinomas. This selective study reaffirms the value of Ep as a biologic marker in some renal cell cancers, and occasionally in other genitourinary tumors.

Further study of fibrinogen degradation products in bladder cancer detection.

A new, rapid immunoassay kit for assaying fibrinogen degradation products (FDP) was studied in 56 patients with cancer of the bladder and in 48 control patients. The specificity of the kit was demonstrated with a small number of false positive results. In bladder cancer patients with low-stage, small superficial tumors, FDP was positive in 32.2 per cent. The combination of urinary cytologic examination with FDP increased the accuracy of the positive results to 80 per cent. The rapid FDP test supplements the urinary cytology in the follow-up and detection of early bladder cancer.

Specificity of renotropin receptors in murine Wilms tumor model.

Contralateral kidneys, removed forty-eight hours after unilateral nephrectomy, contain renotropic growth factors with different effects on normal kidney and Wistar/Furth rat Wilms tumor. Receptors on tumor cells bind factors which, when eluted followed by in vivo bioassay, stimulate the growth of Wilms tumor. Receptors on normal kidney cortex cells bind factors which, when eluted, produce kidney hypotrophy in nontumor-bearing rats.