Comparison of contact and spatial repellency of catnip oil and N,N-diethyl-3-methylbenzamide (deet) against mosquitoes

Nepetalactone, the primary component of catnip oil, was compared with the repellent N,N-diethyl-3-methylbenzamide (deet) for its ability to affect the host-seeking ability of Aedes aegypti (L.). A triple cage olfactometer was used to bioassay each substance and to assess its attraction inhibition (spatial repellent) attributes when combined with the following attractants: carbon dioxide, acetone, a blend of L-lactic acid and acetone, and human odors. Repellent tests were conducted with each substance against female Ae. aegypti, Anopheles albimanus Weidemann, and Anopheles quadrimaculatus Say. Catnip oil and deet were both weakly attractive to Ae. aegypti, catnip oil was the better spatial repellent, whereas deet was a more effective contact repellent in tests with all three species of mosquitoes.     

Cross-reactive trinitrophenylated peptides as antigens for class II major histocompatibility complex-restricted T cells and inducers of contact sensitivity in mice. Limited T cell receptor repertoire

The induction of contact sensitivity in mice by hapten reagents such as trinitrochlorobenzene (TNCB) involves the activation of class II major histocompatibility complex (MHC)-restricted, hapten-specific, CD4⁺ T cells. Reports from different laboratories have indicated that the relevant antigenic epitopes in such reactions might include hapten-conjugated, MHC class II-associated peptides. This study for the first time directly demonstrates that hapten-peptides account for the majority of determinants recognized by trinitrophenyl (TNP)-specific CD4⁺ T lymphocytes. The sequences of those TNP carrier peptides do not have to be related to mouse proteins. Thus, we show that TNP-modified peptides derived from mouse IgG, pigeon cytochrome c or staphylococcal nuclease known to bind to I-A^b or from λ represser with specificity to I-A^d as well as TNP-proteins such as bovine serum albumin, ovalbumin or keyhole limpet hemocyanin all create class II-restricted hapten determinants for a number of TNP-specific T cell clones and hybridomas. All of these cells were induced with cells modified by trinitrobenzene sulfonic acid (TNBS). In addition, we present arguments indicating that individual TNP-specific helper T cells may cross-react with different TNP-peptides bound to identical class II molecules. Chemical treatment of antigen-presenting cells with TNCB or TNBS may thus result in a limited number of particularly repetitive immunodominant hapten epitopes. Immunodominant epitopes were also indicated by an overrepresentation of the TCR elements Vβ2 and Vα10 in I-A^b/TNP-specific T cells. Most importantly, however, we demonstrate that TNP attached to lysine 97 in the staphylococcal nuclease peptide 93–105 (i.e. a clearly “non-self” sequence) is able to prime mice for subsequent elicitation of contact sensitivity by TNCB in the absence of foreign protein. We take this to indicate that those TNP-peptide determinants defined by us as immuno-dominant are responsible for the induction of contact sensitivity to haptens.     

On the kinetics and mechanism of thermal degradation of polystyrene

The thermal degradation of polydisperse polystyrene samples with mol. wts. (M?_n) between 60000 and 22000 has been investigated at different temperatures under oxygen free conditions. Product analysis has been carried out by GPC. The experimental degradation could be simulated by a model consisting of scission and depolymerization. The dynamical behaviour of this model is expressed in a matrix from. The ratio of scission and depolymerization is constant for all polymers and different temperatures during degradation. Therefore, a master curve could be evaluated, which gives a general relation between the decrease of mol. wt. and the mass of volatiles. Finally a radical chain mechanism has been proposed in a lumped form which is consistent with the kinetic model and the experimental results.     

Growth inhibition and transformation of a human fetal tracheal epithelial cell line by long-term exposure to diethylnitrosamine

In order to obtain more information on the in vitro transformationof human cells, a human fetal tracheal epithelial cell line(FHET16/5) was exposed for a long time to diethylnitrosamine(DEN). In 20 passages, this cell line (diploid, male) maintainedstrong immunohistochemical reactivity for carcino-embryonnicantigen and wool merokeratin; it was negative for vimentin.The cells contained PAS-positive mucous substances and ultrastructurallywere found to have desmosomelike attachments. Treatment of thecells was with 0.3% dimethyl sulphoxide (DMSO), or DMSO with150, 450, 1000 or 2000 µg/ml of DEN. It was started atthe ninth passage and continued for six passages over 9 weeksfor the control (DMSO) and the three lowest control doses ofDEN, and for three passages over 9 weeks for the 2000 µg/mlDEN group. Cells grown for 13 days after the end of treatmentwere plated in soft agar and injected subcutaneously in nudemice. The frequency of anchorage-independent colonies grownin soft agar was directly related to DEN dose. Colony-formingefficiency, as an expression of toxic effect, was also dosedependent. Autoradiographically detected unscheduled DNA synthesisindicated an association between anchorage-independent transformationand DNA alterations induced by DEN. Cells injected into nudemice did not produce tumours during a 6-month period, but invasivenesswas observed when cells from the 2000 µg/ml DEN groupwere transplanted on the dermis of cultured chick embryo skin.The results indicate that DEN causes anchorage-independent transformationaccompanied by unscheduled DNA synthesis in a fetal human trachealepithelial cell line.     

Demonstration of Ri-type adenosine receptors in bovine myocardium by radioligand binding

Summary Adenosine has been shown to have negative inotropic, chronotropic and dromotropic effects on the heart. The pharmacological profiles of these effects suggest that they are mediated via R_i (A₁) adenosine receptors, but a direct demonstration of these receptors is still missing. In the present study we report direct labelling of these receptors with (-)N⁶-[¹²⁵I]-p-hydroxyphenylisopropyladenosine ([¹²⁵I]HPIA). The radioligand bound in a saturable and reversible manner to a crude membrane preparation, the B _max-value was 30.5 fmol/mg protein and the K _D-value 1.1 nmol/l. A similar affinity of the ligand was obtained in kinetic and competition experiments. Competition experiments with a variety of adenosine analogues gave a pharmacological profile characteristic of R_i adenosine receptors with high affinities of N⁶-substituted derivatives and a marked stereospecificity for N⁶-phenylisopropyladenosine (PIA). Purification of the membrane preparation by density gradient centrifugation resulted in a 30-fold increase in the number of binding sites which was paralleled by a similar increase in the number of binding sites for [³H]ouabain. Guanine nucleotides decreased binding of [¹²⁵I]HPIA in a dose-dependent manner, but the IC₅₀-values were considerably higher than those reported in other tissues. Finally, binding of [¹²⁵I]HPIA appeared to be entropy-driven which has been shown to be characteristic of agonist binding to R_i adenosine receptors. These results suggest the presence of R_i adenosine receptors in ventricular myocardium which may be responsible for the mediation of the effects of adenosine and its analogues.Abbreviations [¹²⁵I]HPIA (-)N⁶-[¹²⁵I]-p-hydroxyphenylisopropyladenosine - (-)IHPIA (-)N⁶-iodo-p-hydroxyphenylisopropyladenosine - (+)/(-)PIA (+)/(-)N⁶-phenylisopropyladenosine - CHA N⁶-cyclohexyladenosine - NECA 5-N-ethylcarboxamidoadenosine - App(NH)p 5-adenylylimidodiphosphate - Gpp(NH)p 5-guanylylimidodiphosphate     

Effect of the heparinoid pentosan polysulphate (SP 54) on the functional properties of cultured bovine aortic endothelial cells

Summary The effect of the heparinoid, pentosan polysulphate (PP) on the proliferative behaviour of cultured bovine endothelial cells (EC) was examined. In addition, the toxicity of the drug towards EC, its influence on prostacyclin production and release, and on cell-associated plasminogen activator activity was determined. At a concentration of 10 g/ml in the culture medium, PP exerted a growth promoting effect on EC. Increased cell numbers were accompanied by increased ³H-thymidine incorporation into cellular DNA compared with controls, however, final density of the cells was not affected. In contrast, at doses of 1 mg/ml the growth of EC was substantially slowed down. This finding did not reflect cell injury as shown by an unaltered release of ⁵¹Cr from the cells. Incubation of PP with EC had no influence on the prostacyclin release from the cells neither on the accumulation of the metabolite in the culture fluid over 24 hours nor on the releasing capacity upon stimulation with arachidonic acid. PP increased the cell-associated plasminogen activator activity in growing cells and counteracted in cultures at final density the inhibitory effect of serum on the intracellular plasminogenactivator activity. Our results suggest that stimulation of the fibrinolytic activity of the endothelium and a growth promoting effect for endothelial cells that may lead to faster coverage of small lesions could contribute to the antithrombotic potency of pentosan polysulphate in vivo.     

Affinities of barbiturates for the GABA-receptor complex and A1 adenosine receptors: a possible explanation of their excitatory effects

Summary The effects of barbiturates on the GABA-receptor complex and the A₁ adenosine receptor were studied. At the GABA-receptor complex the barbiturates inhibited the binding of [³⁵S]t-butylbicyclophosphorothionate ([³⁵S]TBPT) and enhanced the binding of [³H]diazepam. Kinetic and saturation experiments showed that both effects were allosteric. Whereas all barbiturates caused complete inhibition of [³⁵S]TBPT binding, they showed varying degrees of maximal enhancement of [3H]diazepam binding; (±)methohexital was identified as the most efficacious compound for this enhancement. At the A₁ adenosine receptor all barbiturates inhibited the binding of [³H]N⁶-phenylisopropyladenosine ([³H]PIA) in a competitive manner. The comparison of the effects on [³H]diazepam and [³H]PIA binding showed that excitatory barbiturates interact preferentially with the A₁ adenosine receptor, and sedative/anaesthetic barbiturates with the GABA-receptor complex. It is speculated that the interaction with these two receptors might be the basis of the excitatory versus sedative/anaesthetic properties of barbiturates.Abbreviations GABA -aminobutyric acid - TBPT t-butylbicyclophosphorothionate 1073 - DMBB 5-(1,3-dimethyl)butyl-5-ethylbarbituric acid - MCB N-methyl-5-(1-cyclohexen-1-yl)-5-ethylbarbituric acid - MPPB N-methyl-5-phenyl-5-propylbarbituric acid - PIA N⁶-phenylisopropyladenosine Send offprint requests to M. J. Lohse at the above address     

Tula Virus as Causative Agent of Hantavirus Disease in Immunocompetent Person,Germany

We report molecular evidence of Tula virus infection in an immunocompetent patient from Germany who had typical signs of hantavirus disease. Accumulating evidence indicates that Tula virus infection, although often considered nonpathogenic, represents a threat to human health.     

Is the Parkland formula still the best method for determining the fluid resuscitation volume in adults for the first 24 hours after injury? — A retrospective analysis of burn patients in Germany

BackgroundR Rapid fluid resuscitation is a crucial therapy during the treatment of patients with extensive burns. In 1968, the Parkland Formula was introduced for the calculation of the estimated volume of the resuscitation fluid. Since then, different methods for the calculation of fluid resuscitation volume have been developed. We aimed to evaluate if the Parkland formula is still the most effective method for fluid resuscitation volume calculation in burn patients.MethodsIn the period between January 2015 and January 2019, data from 569 patients over 16 years old with burns of more than 20% total body surface area (TBSA) and at least 15% TBSA full thickness burns were entered in the German burn registry. The patients were divided into 5 groups (0, +1, ?1, +2, ?2) according to the volume of the resuscitation fluid they received. Group 0 patients received the amount of fluid calculated according to the Parkland formula (n = 83). The 4 other groups received reduced (-1, -2) or increased (+1, +2) fluid volumes in comparison to the value obtained by the Parkland formula.ResultsPatients in Group 0 presented a significantly lower mortality in the first week (4.5%) compared to groups –2 (16.7%) and group +2 (19.5%) (p = 0.021). Furthermore, the mean number of operations in group +2 (5.81) was higher than in group ?2 (3.81). Surviving patients from group +2 presented a longer hospital stay (68.1 days) compared to the other groups. Additionally, the logistic regression analysis showed a higher survival of patients in groups ?2 and ?1 (regression coefficients ?0.11 and ?0.086; Odds Ratio 0.896 and 0.918; 95% Confidence Interval (CI) 0,411–1.951 and 0.42–2.004).ConclusionIn this retrospective study, register based analysis a restrictive fluid regime was associated with a higher survival compared to the liberal Parkland guided fluid regime.