A lymphokine distinct from interferon-gamma that activates human monocytes to kill Leishmania donovani in vitro

Human interferon-gamma (IFN-gamma), a T cell lymphokine (LK), activates monocytes to kill many intra- and extracellular pathogens. In fact, previous reports assert that all activity in LK for macrophage activation is due to IFN-gamma. To test this assertion, we examined monocyte interactions with amastigotes of Leishmania donovani after treatment with recombinant DNA or affinity-purified leukocyte IFN-gamma and IFN-gamma containing LK. Cells treated with at least 200 IU/ml IFN-gamma were microbicidal for L. donovani. Analysis of IFN-gamma dose responses for induction of microbicidal activity by recombinant IFN-gamma (r-IFN-gamma) and LK, however, documented a striking difference: LK was 25-fold more efficient than r-IFN-gamma at equivalent IFN-gamma titers. This large difference suggested that monocyte activation factor(s) in LK may not be IFN-gamma. Rabbit anti-IFN-gamma completely inhibited antiviral activity in LK but did not abrogate the ability to induce monocyte cytotoxicity against leishmania. Furthermore, removal of IFN-gamma from LK by monoclonal anti-IFN-gamma affinity chromatography or by treatment with anti-IFN-gamma followed by staphylococcal protein A chromatography also did not inhibit LK activity. Fractionation of LK on Sephadex G-100 revealed two activity peaks: one in the 50,000 to 60,000 m.w. range coincident with IFN-gamma, and the other at 25,000 to 30,000 daltons with no IFN-gamma. These studies document LK physicochemically and antigenically distinct from IFN-gamma that activate monocytes to kill L. donovani. Such novel factors may have broad import for the study of macrophage-mediated host defenses and for development of immunotherapeutic regimens.     

Estimation,Testing and Adjustment of Transient Healthy Entrant Effects

At recruitment, cohorts often selectively exclude non-healthy individuals with symtoms prodromal to the response. After a certain time from study entry, the health status of participants regresses towards the underlying population. Methods developed here estimate, test and adjust out this transient healthy entrant effect from survival function estimation. In the simplest case, each participant's time is divided into: Ω₁ - immediately after study entry while these transient healthy entrant effects are strong, and Ω₂ - later, after they have vanished or greatly diminished. Truncated Kaplan-Meier models fit separately to risk sets in Ω₁ and Ω₂ quantify and remove the bias from transient healthy entrant effects and test for statistical significance. If sufficient data are available, these methods can be expanded to dividing the subjects' time into multiple subperiods or fitting specific models of attenuation for the transient healthy entrant effect. Examination of nickel refinery workers and an HIV-1 infected cohort suggest that, without the adjustments proposed here, transient healthy entrant effects cause moderate overestimations of survival probability.     

Effects of guinea pig vasoactive intestinal peptide on the isolated perfused guinea pig heart

The pharmacological effects of guinea pig vasoactive intestinal peptide (VIP) were studied in isolated perfused guinea pig hearts. Bolus injections of VIP produced a dose-dependent tachycardia that was not affected by atenolol. A decrease in amplitude of ventricular contractions occurred in response to all doses of VIP. This response was preceded by a small increase in amplitude in 3 of 6 hearts at the highest dose. VIP produced a decrease in perfusion pressure which was prominent after coronary tone was elevated with [Arg8]-vasopressin. The present findings support speculation that VIP may have a role in the regulation of heart rate and coronary blood flow.     

Visceral perception versus visceral detection: disentangling methods and assumptions

A within-subject experiment compared three paradigms commonly used in visceral perception: self-report, heartbeat tracking, and signal detection. Eighteen undergraduates estimated heart rate using each technique while engaging in a number of separate tasks conducted a week apart. Although all three techniques significantly tapped accuracy of heart rate perception, only the self-report and signal detection methods were reliable over time. Most important, there was no relationship involving any of the methods in measuring accuracy. The findings suggest some fundamental differences in the assumptions and perceptual properties of the various paradigms. A distinction is made between visceral perception and detection. Perception implies the subject's use of both internal physiological and external environmental information in the perception of visceral state. Detection connotes the subject's use of only physiological information--to the exclusion of all other factors. The relevance of these approaches for biofeedback and real-world symptom perception is discussed.     

Tritrophic interactions in the context of climate change: a model of grasses, cereal Aphids and their parasitoids

Biologists have been challenged to envisage the likely consequences of increases in atmospheric carbon dioxide concentrations, and the suite of accompanying environmental changes (e.g. rising temperature, changing rainfall patterns, etc.) on our biotic systems. Research to date on plant responses has been extensive, but work on herbivore responses has been less complete, and work on higher trophic levels nearly nonexistent. One group of herbivores that has been reasonably well studied is aphids, and at least for this group, researchers have even begun to investigate responses at higher trophic levels, to include parasitoids. In this paper, we develop a mechanistic mathematical model of the general interaction between grasses, cereal aphids and their parasitoids. We used this model to investigate the interacting effects of rising CO₂ and temperature. The model suggests that, while parasitoids do have an impact on the aphid colony population dynamics, they do not fundamentally alter the aphid response to climate change. The model predicts that for both aphids and their parasitoids, the population responses to combined effects of elevated CO₂ and temperature will be more similar to current ambient conditions than we might expect from the individual effects of CO₂ or temperature increases. This interaction has important consequences for the interpretation of results from experiments that study only the effect of rising CO₂.     

Antibody production and growth of mouse hybridoma cells in Nutridoma media supplements

Traditionally, cell culturists have relied upon the addition of serum to culture medium for the growth and maintenance of cell lines. However, many aspects of the use of serum in tissue culture are problematic. Cell culture supplements that circumvent the need for serum are readily available and provide a consistent protein composition. This defined environment allows the antibody to be more easily purified from culture supernatants. Nutridoma media supplements were formulated to support the growth of lymphoblastoid cells in a defined culture environment. In this study, Nutridoma media supplements were tested in parallel with serum-containing cultures to determine if Nutridoma supplemented medium is effective in supporting hybridoma cell growth and antibody production in three hybridoma cell lines. Data, based on cell growth and antibody production, show the importance of basal media selection when serum is replaced with Nutridoma media supplements. SDS-PAGE results show that cell supernatants from Nutridoma supplemented cultures contain very few contaminating proteins.     

Field endoscopy for identifying gender, reproductive stage and gonadal anomalies in free-ranging sturgeon (Scaphirhynchus) from the lower Mississippi River

Thirty-six sturgeon ( Scaphirhynchus spp.) were captured from the lower Mississippi River using baited trot-lines, anesthetized using tricaine methanesulfonate, and subjected to endoscopic evaluation of their coelom (coelioscopy) on the river bank. Using a 2.7 mm rod-lens telescope and gravity–fed sterile saline infusion, gender and reproductive stage were determined in the field, and later re-evaluted and confirmed by histology of endoscopic biopsies in the laboratory. Gender and reproductive stage were determined endoscopically in all fish without complication, and proved to correlate 100% with biopsy histology. Modern rod-lens telescopes and sterile saline insufflation can be used under field conditions, provide superior visualization of sturgeon gonads, and offer a high degree of accuracy even with inactive gonads. Rigid endoscopy is recommended as a minimally-invasive means of assessing the reproductive organs of sturgeon and other fish.