Search

The study of temperature-dependent sex determination (TSD) in vertebrates has attracted major scientific interest. Recently, concerns for species with TSD in a warming world have increased because imbalanced sex ratios could potentially threaten population viability. In contrast, relatively little attention has been given to the direct effects of increased temperatures on successful embryonic development. Using 6603 days of sand temperature data recorded across 6 years at a globally important loggerhead sea turtle rookery-the Cape Verde Islands-we show the effects of warming incubation temperatures on the survival of hatchlings in nests. Incorporating published data (n = 110 data points for three species across 12 sites globally), we show the generality of relationships between hatchling mortality and incubation temperature and hence the broad applicability of our findings to sea turtles in general. We use a mechanistic approach supplemented by empirical data to consider the linked effects of warming temperatures on hatchling output and on sex ratios for these species that exhibit TSD. Our results show that higher temperatures increase the natural growth rate of the population as more females are produced. As a result, we project that numbers of nests at this globally important site will increase by approximately 30% by the year 2100. However, as incubation temperatures near lethal levels, the natural growth rate of the population decreases and the long-term survival of this turtle population is threatened. Our results highlight concerns for species with TSD in a warming world and underline the need for research to extend from a focus on temperature-dependent sex determination to a focus on temperature-linked hatchling mortalities.

Informationentragende Nukleinsauren sind universell uber 3′-5′-Bindungen verknupft. Regioisomere 2′-5′-Verknupfungen bilden sich dagegen unregelmasig wahrend der nichtenzymatischen RNA-Synthese und waren womoglich hilfreich fur die prabiotische RNA-Replikation. Hier berichten wir uber die enzymatische Synthese von DNA und RNA mit ortsspezifischen 2′-5′-Verknupfungen durch ein gezielt verandertes Polymerase-Enzym, das 3′-Desoxy- oder 3′-O-Methyl-NTPs als Substrat verwendet. Zusatzlich vermelden wir die reverse Transkription der so hergestellten, modifizierten Nukleinsauren zuruck in 3′-5′-verknupfte DNA mit guter Fidelitat. Somit ergibt sich eine schnelle und einfache Methode zur “strukturellen Mutagenese” durch positionsselektives Einfugen von 2′-5′-Verknupfungen, durch die, ohne Anderung der Basensequenz, die Struktur und Funktion von Nukleinsauren anhand lokaler Deformationen durch regioisomere Bindungen untersucht werden kann. Beispielhaft wenden wir diese Methode auf das 10-23-RNA-Endonuklease-DNAzym an.

This study characterized the pharmacokinetics (PK) of mepolizumab, after a single intravenous (IV), subcutaneous (SC), or intramuscular (IM) dose in healthy adults and determined the absolute bioavailability of SC and IM mepolizumab delivered at different anatomical regions. Sixty healthy subjects were randomly assigned to receive a single dose of either mepolizumab 250 mg by IV, SC injection (upper arm, abdomen, or thigh); or IM injection (thigh). Following IV administration, the mean maximum observed plasma mepolizumab concentration (Cmax ) and the mean area under the concentration versus time curves from time zero to infinity (AUC(0-∞) ) were 109 ± 17 µg/mL and 1,557 ± 250 µg d/mL, respectively. After SC administration, the mean (±SD) values of Cmax and AUC(0-∞) were 34.1-38.2 ± 7.3-12.1 µg/mL and 1,110-1,238 ± 228-372 µg d/mL, respectively. Following IM administration, the mean values of Cmax and AUC(0-∞) were 46.9 ± 10.6 µg/mL and 1,395 ± 348 µg d/mL. The median terminal half-life was similar for SC, IM and IV administration (17.9-20.4, 19.2, and 18.5 days, respectively). The overall mean bioavailability of SC mepolizumab was 64-75%, and absorption was relatively similar for the three SC injection sites. Mepolizumab 250 mg was generally well tolerated in this study. These results support flexibility in the SC injection site for mepolizumab.

Aim For the 9% to 16% of children with cerebral palsy (CP) who have normal brain imaging, further testing for metabolic and/or genetic conditions has been recommended. This study aimed to identify a cohort of children with CP with normal magnetic resonance imaging (MRI), clinically review and describe the cases, and assess the value of testing for inherited metabolic disorders in these children. Method Children with congenital CP born from 1999 to 2005 were selected from a population register. Normal MRI reports were identified and the scans reassessed. Children whose scans were performed before 18 months were excluded, as were children with spastic CP (Gross Motor Function Classification System [GMFCS] level I). The remainder were reviewed clinically and offered investigations. Results Of 730 children identified, 515 had available imaging and 54 were confirmed as normal. Cases with non-spastic CP and those with milder clinical severity were more likely to have normal imaging. Twenty-three children (17 males, six females; mean age 6y 11mo, SD 1y 10mo, range 3y 0mo to 10y 0mo) were reviewed clinically and offered investigations. Twelve children had spasticity (11 with diplegia, one quadriplegia), three had dyskinesia, five ataxia, and three hypotonia. Two children functioned in GMFCS level I, 11 in level II, seven in level III and three in level IV. Four children with spasticity had unusual features. No alternative diagnoses were made. Interpretation Although important to consider in individual cases, comprehensive metabolic testing failed to clarify the aetiology of CP further in this large cohort of children with normal MRIs, even those with atypical features.

A series of a-vinyl arylmethyl cations were generated and studied using nanosecond laser flash photolysis. Rate constants for the decay of the substituted a-vinyl arylmethyl cations were determined under solvolytic conditions in pure solvents and solvent mixtures of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and 2,2,2-trifluoroethanol (TFE). In addition the absolute reactivity of the carbocations with added nucleophiles were obtained. The reactivities of the a-vinyl arylmethyl cations were then compared to the reactivities of the corresponding a-methyl, a-phenyl, and a-cyclopropyl arylmethyl cations. Hammett s R plots of each of the series of carbocations were obtained and the substituent effects on carbocation reactivity analyzed. These data show that the influence of substituent on the reactivity of the a-vinyl carbocations was different from the substituents effects on the reactivity of the a-methyl, a-phenyl, and a-cyclopropyl series. Copyright 2008 John Wiley & Sons, Ltd.

— The effect of an alternating current (AC) magnetic field (MF) on radical behavior is identical to that exerted by a direct current (DC) field of the same instantaneous strength provided that the frequency is low enough in comparison with radical pair dynamics. This criterion is easily met by environmental fields. In general, combined AC/DC fields will lead to increased radical concentrations and oscillating free radical concentrations. Interestingly, the frequency of oscillation for radical concentration seldom follows exactly the pattern of the external AC component of the MF. Even the simple case of an AC-only field at 60 Hz can lead to oscillations in radical concentrations at 120 Hz. The concentration time dependence patterns can be even more complex when the singlet and triplet levels of the radical pair are not degenerate. Further, the effects can change dramatically depending upon the absolute and relative values of the AC and DC components, thus providing a possible explanation for MF windows for certain effects reported experimentally. Effects on the average radical concentration are probably relevant only for fields higher than about 0.1 gauss. Oscillating radical concentrations may influence signal transduction processes or other cellular mechanisms; at the present time there is not enough knowledge available to establish a reasonable threshold for these types of effects. This contribution aims at providing a solid foundation to guide the experimentalist in the design of meaningful experiments on the possible role of MF perturbations of radical chemistry on biological response.

Information-bearing nucleic acids display universal 3'-5' linkages, but regioisomeric 2'-5' linkages occur sporadically in non-enzymatic RNA synthesis and may have aided prebiotic RNA replication. Herein we report on the enzymatic synthesis of both DNA and RNA with site-specific 2'-5' linkages by an engineered polymerase using 3'-deoxy- or 3'-O-methyl-NTPs as substrates. We also report the reverse transcription of the resulting modified nucleic acids back to 3'-5' linked DNA with good fidelity. This enables a fast and simple method for "structural mutagenesis" by the position-selective incorporation of 2'-5' linkages, whereby nucleic acid structure and function may be probed through local distortion by regioisomeric linkages while maintaining the wild-type base sequence as we demonstrate for the 10-23 RNA endonuclease DNAzyme.

In the greater bandicoot rat, Bandicota indica, of south-east Asia, nine cell associations were documented in the testicular seminiferous epithelium. In about 10% of the tubule cross sections two or more cell associations occurred and, furthermore, some of the generations of germ cells within the cell associations were sometimes either out of phase, or missing, in the tubule cross sections. These features, together with the fact that this species has a highly pleiomorphic sperm head shape, are somewhat reminiscent of those of the seminiferous epithelium in humans and some other primates but not of common laboratory rodents. This species could thus be a good model for investigating irregular patterns of spermatogenesis in naturally occurring wild species of rodent.

The messenger RNA coding for chicken vitellogenin, a precursor of the egg-yolk proteins lipovitellin and phosvitin, is synthesized in the liver following estrogen injection. This mRNA is 6600 nucleotides long. We have previously reported the cloning and preliminary characterization of some cDNA fragments representing portions of the vitellogenin mRNA [Biochem. Biophys. Acta, 606, 34--46 (1980)]. In this paper we report the full characterization of a larger series of such clones, representing almost the entire length of the mRNA, by restriction endonuclease mapping, R-loop mapping, RNA-DNA hybridization and by translation in vitro of the RNA which hybridizes to the cloned DNA. From the results we conclude that the chicken vitellogenin mRNA, unlike that of Xenopus laevis, does not vary in sequence over most of its length, although some variations in the cDNA sequences were detected particularly in clones derived from the 3' terminus of the RNA. All sequence variants appear to be present in RNA prepared from single animals. The possible origins of these minor species are discussed. Furthermore, we describe a cDNA clone complementary to an mRNA which is about the same size as vitellogenin mRNA and which codes for an egg yolk protein antigenically related to lipovitellin. This mRNA is synthesized constitutively.

The introduction of professional revalidation and clinical governance imposes an increasing requirement for clinicians to provide evidence of competence. This paper introduces a CUSUM (CUmulative SUM) mathematical tool for determining trend and applies the technique to 84 consecutive parotidectomies (superficial, partial or total/near total) performed by one surgeon (J.S.). Using this operation, the paper illustrates how attainment and maintenance of competence in the field of otolaryngological surgery may be demonstrated at differing levels of rigour. The role of the CUSUM in assessing a trainee's surgical progress is also explored.

Providing data as evidence of good practice is becoming imperative to meet the demands of professional revalidation and clinical governance. Sensitivity and specificity are common performance measures in fine needle aspiration (FNA) but are vulnerable to discordant analytical methods. We introduce a CUSUM technique and show how it may be used to show attainment and maintenance of proficiency in head and neck (HN a fact that must be recognized by anyone devising minimum performance values.

In this postal survey of 1064 health service staff working closest to the Omagh bombing in Northern Ireland, approximately half reported having professional or civilian involvement. Types of involvement and posttraumatic stress disorder (PTSD) levels varied between staff groups. Staff involved both professionally and as a civilian, particularly those who witnessed the trauma, or those who had experienced previous emotional problems and trauma, had the highest levels of symptomatology. Although staff with higher PTSD symptoms were more likely to seek professional help, only a minority contacted professionals for support.

A calculated 3-D model of the kinase domain of the epidermal growth factor receptor (EGF-R) protein-tyrosine kinase (PTK) was used to develop a pharmacophore model for ATP-competitive inhibitors and, subsequently, a new class of selective EGF-R kinase inhibitors. CGP 59326A, a highly selective and potent inhibitor of the EGF-R in vitro, inhibited the proliferation of EGF-R-expressing epithelial lines, while having little anti-proliferative activity against EGF-R-negative lines. In contrast to previously described inhibitors, CGP 59326A had potent and selective in vivo anti-tumor activity at well-tolerated doses against EGF-R-expressing tumors (e.g., ED50 of 0.78 to 1.5 mg/kg for inhibition of A431 tumor growth). CGP 59326A inhibited growth of human tumor xenografts expressing the EGF-R but showed little activity against EGF-R-negative xenografts. Combination of CGP 59326A with cytotoxic agents resulted in tumor regression and cures. The high selectivity and attractive biological profile of CGP 59326A suggest that it could have therapeutic value in the treatment of proliferative diseases which involve mitogenic signaling from the EGF-R.

We have examined the behavior of radical pairs derived by hydrogen abstraction of triplet benzophenone and some of its derivatives from bovine serum albumin, human serum albumin and calf thymus DNA. They have been investigated by means of nanosecond laser flash photolysis techniques. The dynamics of radical pair behavior are shown to be sensitive to external magnetic fields; these effects are interpreted using the established model for the influence of magnetic fields on radical pairs in micellar aggregates, in which intersystem crossing of the radical pair is slowed by the external magnetic field. Our results indicate that proteins and DNA can confine the radicals for a sufficiently long period of time for spin evolution to be affected by external fields. In proteins the radical pair retains its geminate character (i.e. remains confined) for about 0.5-1 microsecond. Interestingly, the magnetic field effects observed in proteins and in DNA seem to occur in distinct timescales; for example, for 2,3,4,5,6-pentafluorobenzophenone bound to DNA, the magnetic field alters the radical reactivity only over times < or = 50 ns, suggesting poor confinement. The timescale for these effects can be increased by promoting Coulombic attraction between DNA and the radical precursor. Electron transfer interactions play a role in the case of DNA.

A series of potent HIV-protease inhibitors has been prepared. Several of the newly synthesized compounds showed high plasma levels after oral administration to animals. Based on the overall biological profile, CGP 61755 was chosen for further preclinical evaluation. For this compound, a 10 step synthesis potentially suitable for large scale production was developed.

Although the effect of Zn in soil on Cd uptake by plants has been studied extensively there appears to be no consensus in the literature about the interactions. Furthermore, the majority of investigations have studied soils containing elevated concentrations of Cd or Zn as a result of pollution, e.g., the application of sewage sludge to the soil. The accumulation of Cd by wheat (Triticum aestivum L.) grain grown at nine sites across South Australia was investigated. Applications of low rates of Zn fertilizer (up to 5.0 kg Zn ha{sup -1}) were found to markedly decrease the Cd concentration in wheat grain grown in areas of marginal to severe Zn deficiency. No further significant decreases in Cd concentration in grain occurred at higher rates of applied Zn. Effectiveness of applied Zn on grain Cd concentration decreased with time since application. Grain Cd concentrations decreased with fresh and residual applications of Zn fertilizer (up to 5.0 kg Zn ha{sup -1}). Soil tests may provide useful guides to situations where Cd concentrations in grain may be beneficially decreased by Zn applications. 25 refs., 4 figs., 4 tabs.

:A model for magnetic field effects in biological systems is proposed. This model employs the basic concepts of the radical pair mechanism, and predicts that magnetic fields will increase the average radical concentration, lengthen their lifetime and enhance the probability of radical reactions with cellular components. The relevance of these effects in relation to cancer initiation, promotion and progression is discussed.

Laser flash photolysis of 1,3-dimethoxybenzene and five substituted derivatives (2-Me, 4-Me, 5-Me, 2-MeO, 4-MeO) in 1,1,1,3,3,3-bexafluoroisopropyl alcohol (HFIP) results in a single transient with λ max in the range 395-460 nm, dependent on the additional substituent. This transient forms in a monopbotonic process,in unaffected by oxygen, but quenched by methanol and bromide, and decays by returning to the ground-state aromatic compound

9-Arylfluoren-9-yl cations have been observed as transient intermediates upon 248 nm laser photolysis of 9-arylfluoren-9-ols in 2,2,2-trifluoroethanol (TFE) and 1:4 (v/v) acetonitrile–water. Quantum yields for the formation of the cations were measured and found to lie in the range 0.5–0.8. Rate constants for the decay of the cations in the two solvents parallel each other, a plot of log kTFEversus log kw being linear with a slope of 1.00. These rate constants are approximately two orders of magnitude larger than those observed in the same solvent for the corresponding monosubstituted triarylmethyl cations. Substituent effects in the two series are similar. For both the hydration reaction and the overall equilibrium, a two-parameter treatment dissecting the substituent contributions into resonance and polar effects shows that the former are more important in the triarylmethyl series, while the latter are more important in the fluorenyl series. Twisting of the 9-aryl ring out of coplanarity with the fluorenyl ring is the likely cause of the diminished resonance interaction in this system. The 1-(4-dimethylaminophenyl)ethyl cation has been observed in TFE and 1:1 TFE–W, being generated by photoprotonation of 4-dimethylaminostyrene. Rate constants for decay are about 50 times smaller than those previously estimated by a clock method. The failure of the latter approach is associated with the rate constant for the clock nucleophile becoming significantly less than diffusion control for this highly stable cation. An extended log kw–pKR correlation is constructed. This shows a series of reasonably parallel lines associated with different families. In considering cations with the same pKR′ the order of inherent reactivity is 9-unsubstituted-9-xanthylium ∼ cyclic dialkoxy-carbocation > phenyltropylium > diarylmethyl ∼9-arylxanthylium > triarylmethyl ∼9-arylfluoren-9-yl. The log kw–pKR data for each family are reasonably satisfied by a linear relationship, with a slope d(log kw)/dpKR of 0.6 ± 0.1. The triarylmethyl and 9-arylfluoren-9-yl cations form a contiguous series covering 26 pKR units. The data for these indicate that there is probably a gentle downward curvature in the correlation, particularly at the high reactivity end. This is consistent with a Hammond effect on the transition state such that it becomes more cation-like in the hydration direction for more reactive cations.

The photochemistry of cis-1-phenylcyclohexene and its m-methoxy derivative has been examined in 1,1,1,3,3,3-hexafluoroisopropyl alcohol (HFIP). The only photoproduct is the Markovnikov adduct of the solvent, arising from an intermediate 1-arylcyclohexyl cation. This cation is observed as a transient species with laser flash photolysis, for both direct irradiation at 248 nm and benzophenone sensitized irradiation at 308 nm. As suggested in previous studies with phenylcyclohexene in other solvents, the mechanism involves protonation of a strained trans-1-arylcyclohexene formed from both the singlet and triplet excited states. The trans-cyclohexene is not observed in HFIP because of its very rapid protonation by this solvent

4-Methoxyphenethyl cations bearing β-fluorine substituents [4-MeOC6H4C+R1R2 with R1= H, R2= CH2F (3), R1= H, R2= CHF2(4), R1= H, R2= CF3(5), R1R2= CF3(6)] are observed as transient intermediates following 248 nm laser photolysis of chloride or bromide precursors ArC(–X)R1R2 in 2,2,2-trifluoroethanol (TFE) and TFE–water mixtures. Corresponding phenethyl radicals are also observed; successive fluoro-substitution has remarkably little effect on the Absorbance(cation): Absorbance-(radical) ratio. Rate constants ks for the decay of the cations have been directly measured, and compared with those of non-fluorinated analogues. In TFE–water mixtures the reactivity order is ArCH+CHF2 > ArCH+CH2F > ArCH+CF3 > ArCH+CH3(1) > ArC+(CH3)2(2) > ArC+(CF3)2, but the differences are small, there being little more than a two-order of magnitude decrease across the series. This remarkably small effect of fluorine had previously been observed in an examination of azide:solvent partitioning ratios kaz:ks. Rate constants kaz have also been obtained in this work, and, with the exception of 2 which reacts somewhat more slowly, these are constant, with values consistent with the azide : cation combination occurring at the diffusion limit for these cations, as had been assumed in the previous work. The small, complex effects of fluoro substitution on the reactivities of these cations have been explained by a model which has, as a key component, an effect of electron withdrawing substituents of forcing the positive charge away from the benzylic carbon to the oxygen of the 4-methoxy group. Evidence for a significant perturbation of the π electron density is available in the present work, in that the absorption maxima of the α-CF3and bis-α-CF3 cations 5 and 6 are shifted 20 nm and 50 nm, respectively, to lower wavelengths than the corresponding α-methyl derivatives 1 and 2. Studies of 6 in 100% aqueous solution reveal a second, slower, transformation following the decay of the cation. Product studies have previously indicated that a fraction of the hydration of this cation occurs at the 4-position of the aromatic ring, producing a quinone methide and products arising from such a species. An unobserved hemiacetal is an intermediate in this sequence. From spectral and kinetic considerations the second process observed with flash photolysis has been identified as representing the breakdown of the hemiacetal to the quinone methide. A complete rate–pH profile for this reaction has been obtained, from which a pKa of 11.0 has been determined for the ionization of the hemiacetal.

The dynamics of reactions of carbon-centered 1-arylalkyl radicals with bromine or chlorine attached to the carbon adjacent (β) to the radical center have been examined using nanosecond laser flash photolysis. The primary reaction of the radicals containing the electron-donating 4-methoxy group on the phenyl ring is highly dependent on the solvent composition. In weakly ionizing solvents such as acetonitrile, the radicals decay in a second-order manner indicating that coupling of two radical centers is the primary mode of radical decay. However, when the ionizing ability of the solvent is increased by addition of water, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), or 2,2,2-trifluoroethanol (TFE), heterolysis of the β-substituent becomes the dominant mode of decay. The occurrence of the heterolysis reaction is demonstrated unambiguously by direct observation of the radical cation produced as the primary, heterolysis product. The rate constants for and yield of the heterolysis reaction are found to be dependent...

A series of four symmetrical squaraines (ditoylyl, di-m-xylyl, dianisyl, and diresorcinyl) incorporated inside zeolites Y, mordenite, and ZSM-5 have been obtained by treating squaric acid and the corresponding arene in the presence of acid zeolites. Acid sites and high reaction temperatures (150 °C) were found to be crucial for the success of the preparation procedure. Surprisingly, this method failed for the preparation of the squaraine derived from N,N-dimethylaniline, which is known to be readily formed from squaric acid in homogeneous phase without a catalyst. The solid samples containing squaraines were characterized by diffuse reflectance and Raman spectroscopies and by thermogravimetry−differential scanning calorimetry. Among the hosts, mordenite was found to be the most general and convenient zeolite for the preparation of the squaraines, while in the other solids either the organic content adsorbed was comparatively smaller (ZSM-5) or some squaraines were not very stable (Y zeolite for ditolyl an...

As part of a larger study looking at the processes and outcomes of psychological treatments for white-collar workers suffering from stress at work, changes in job perceptions and symptoms which took place over the course of psychotherapy were assessed in order to explore the relationship over time between changes in clinical state and changes in job perceptions. Following psychological treatment, clients showed both a reduction in symptomatology and anxiety, and viewed their jobs more positively. Moreover, there were significant relationships between changes in symptom levels and changes in job satisfaction and in attitudes towards opportunity for control, skill use, feeling valued and interpersonal contact. Other attitude change, such as perceptions of variety and clarity in the job, showed little relationship with clinical improvement. This suggests that while some job perceptions may be related to the levels of stress or clinical symptoms suffered by individuals, other perceptions are more independent and are likely to reflect the influence of organizations on individual health. This supports the need for stress management to be targeted at both the individual and organizational level.

This study of a longitudinal investigation of 170 junior doctors, followed from when they were students, was designed to contribute to the organizational–individual debate over the causes of job stress and especially to address some of the criticisms of those studies which see stress as largely dispositional. It considers individual and organizational predictors of job attitudes and stress, in particular the roles played by personality variables relevant to their job (self-criticism, empathy and dependency), family variables of perceived early relationships, early loss or separation, and parents' ages, as well as more traditional factors of initial stress levels and role satisfaction (all measured as students) together with present objective measures of hours worked, responsibility levels and type of hospital. It was found that the main predictors of job stress were self-criticism and father's age, while job attitudes were predicted by relationship to mother and student role satisfaction. The non-family predictors were in turn predicted by family variables. In addition, those who had suffered parental loss or separation when young were more likely to reach a clinical level of symptoms. Finally, the importance of both organizational and individual factors was indicated by the finding that the level of perceived stress caused by senior doctors was predicted first by the type of hospital and almost as strongly by relationships with fathers. This is seen as an empirical indication of psychoanalytical transference in job stress. The results suggest underlying mechanisms for the dispositional approach to job perceptions and stress, though the organization remains important and requires more detailed assessment.

Do evaluations of psychotherapy sessions predict treatment outcome? Clients (n = 40) and their therapists rated each session (n = 16 per client) of their brief therapy on the Session Evaluation Questionnaire (SEQ), which yields indices of session Depth (power, value) and Smoothness (comfort, safety). External raters rated tape-recordings of half of the sessions. SEQ ratings by one of two principal therapists were strongly correlated with client improvement on self-report measures; those of the other therapist were not. Clients' SEQ ratings did not show the expected correlations with improvement. External raters' ratings of session Smoothness were significantly correlated with client improvement on some measures.