Role of neutrophils in lung vascular injury and edema after premature birth in lambs

Carlton, David P., Kurt H. Albertine, Soo Chul Cho, MennoLont, and Richard D. Bland. Role of neutrophils in lung vascular injury and edema after premature birth in lambs. J. Appl. Physiol. 83(4): 1307-1317, 1997.Toinvestigate the role of neutrophils in the pathogenesis of respiratorydistress after premature birth, we assessed the relationship betweencirculating neutrophil concentration and neutrophil accumulation in thelung, lung lymph and pleural liquid flow, and extravascular lungwater in 10 chronically catheterized preterm lambs (127 ± 1 days gestation) that were mechanically ventilated for 8 h afterbirth. Circulating neutrophil concentration transiently decreasedwithin 2 h after birth and then returned to prenatal values by 6-8h. The decrease in circulating neutrophil concentration was relateddirectly to the accumulation of neutrophils in the air spaces, drainageof liquid and protein from the lung 6-8 h after delivery, andpostmortem extravascular lung water. In additional studies, weintravenously administered mechlorethamine to 5 fetal lambs to reducecirculating neutrophils before delivery (neutrophil concentrationbefore birth: 9 ± 11 cells/µl). Compared with control lambs,neutrophil-depleted lambs had significantly less drainage of liquid(7.8 ± 5.9 vs. 2.6 ± 1.9 ml/h, respectively) and protein (116 ± 74 vs. 42 ± 27 mg/h, respectively) from the lung 6-8 hafter birth and significantly less extravascular lung water atpostmortem (6.5 ± 0.8 vs. 4.8 0.6 g/g dry lung,respectively). Thus neutrophils contribute to thepathogenesis of respiratory distress after premature birth byincreasing lung vascular protein permeability and promoting lung edema.

     

Feeding Behavior Modulates Biofilm-Mediated Transmission of Yersinia pestis by the Cat Flea,Ctenocephalides felis

Background

The cat flea, Ctenocephalides felis, is prevalent worldwide, will parasitize animal reservoirs of plague, and is associated with human habitations in known plague foci. Despite its pervasiveness, limited information is available about the cat flea’s competence as a vector for Yersinia pestis. It is generally considered to be a poor vector, based on studies examining early-phase transmission during the first week after infection, but transmission potential by the biofilm-dependent proventricular-blocking mechanism has never been systematically evaluated. In this study, we assessed the vector competence of cat fleas by both mechanisms. Because the feeding behavior of cat fleas differs markedly from important rat flea vectors, we also examined the influence of feeding behavior on transmission dynamics.

Methodology/Principal Findings

Groups of cat fleas were infected with Y. pestis and subsequently provided access to sterile blood meals twice-weekly, 5 times per week, or daily for 4 weeks and monitored for infection, the development of proventricular biofilm and blockage, mortality, and the ability to transmit. In cat fleas allowed prolonged, daily access to blood meals, mimicking their natural feeding behavior, Y. pestis did not efficiently colonize the digestive tract and could only be transmitted during the first week after infection. In contrast, cat fleas that were fed intermittently, mimicking the feeding behavior of the efficient vector Xenopsylla cheopis, could become blocked and regularly transmitted Y. pestis for 3–4 weeks by the biofilm-mediated mechanism, but early-phase transmission was not detected.

Conclusions

The normal feeding behavior of C. felis, more than an intrinsic resistance to infection or blockage by Y. pestis, limits its vector competence. Rapid turnover of midgut contents results in bacterial clearance and disruption of biofilm accumulation in the proventriculus. Anatomical features of the cat flea foregut may also restrict transmission by both early-phase and proventricular biofilm-dependent mechanisms.     

Production and characterization of polyclonal and monoclonal antibodies against Aflatoxin B1 oxime-BSA in an enzyme-linked immunosorbent assay

From a single aflatoxin B₁ oxime — bovine serum albumin conjugate, polyclonal and monoclonal antibody preparations were produced. The four rabbit polyclonal antisera were specific for aflatoxin Bi in a microtitration plate enzyme — linked immunosorbent assay. The monoclonal antibodies showed a wide range of differing specificities, recognizing, for example, aflatoxins B₁, B₂, G₁ and G₂; B₁ and B₂; B₁ and G₁; and G₁ alone. No antibody preparations reacted with aflatoxin M₁. The significance of these results to the strategy of anti-aflatoxin antibody production for use in quantitative enzyme immunoassays is discussed.     

Ethanol Perturbs Glycosylation and Inhibits Hypersecretion in Trichoderma reesei

The effects of ethanol and phenylethanol on the growth of and glycoprotein secretion by Trichoderma reesei were studied. Low levels (1.5%, vol/vol) of ethanol perturbed the glycosylation process, as shown by alterations in the isoelectric profile of the secreted proteins and a reduction in the rate of incorporation of mannose into oligosaccharides. In addition to these effects on posttranslational modification, ethanol drastically lowered the protein secretion level of a hypersecretory strain.     

The use of bacterial alginates to prepare biocontrol formulations

Summary Formulations which are economical and which can deliver a viable organism are critical to developing successful biocontrol products for plant pathogens. In the present study, alginates derived from commercial kelp and produced byAzotobacter vinelandii isolates ATCC 9104 and 12 837 were compared in their ability to form stable, biodegradable granular formulations of the biocontrol fungiTalaromyces flavus andGliocladium virens. Bacteria were grown in shake flask cultures (180 rpm) at 32°C for 104 h. The cultures were monitored for pH, dissolved oxygen, glucose concentration, dry cell weight, and alginate dry weight. Aqueous solutions of the bacterial alginates, as well as the kelp-derived alginate products, gelled readily in 0.25 M calcium chloride. Mannuronate (M) and guluronate (G) compositions of the alginate samples were determined by circular dichroism. M/G ratios for cultures of isolate 12837 averaged 0.98±0.18; for isolate 9104, 1.59±0.12; and for kelp, 1.54±0.39. The viability ofT. flavus in the kelp and bacterial alginate formulations were similar over 84 days. An exploratory experiment indicated good viability ofG. virens using the same bacterial alginates. This study demonstrated a practical use for bacterial alginate as a potentially less costly substitute for kelp alginate in the preparation of biocontrol agent formulations.     

Cellulase secretion from a hyper-cellulolytic mutant of Trichoderma reesei Rut-C30

Two strains of Trichoderma reesei, wild type QM6a and mutant Rut-C30, were grown in meida containing an inducer, insoluble crystalline cellulose (Avicel PH101), as carbon source for 11 days. The cell growth, expressed as myceliar protein content, of Rut-C30 was 4–5 times higher than QM6a. The lack of ultrastructural disorganization, and absence of intracellular enzyme release into the growth medium, indicated that none of these two strains had undergone any significant autolysis during the entire growth phase. Cellulase activities, mainly endoglucanase, cellobiase and filter paper degrading activity (disc) were enhanced in Rut-C30 cells. A major change was observed in the endoglucanase activity which was 30 times higher in Rut-C30 than QM6a, whereas, both -glucosidase and disc activities were 3 times enhanced in Rut-C30 compared to QM6a. In addition to synthesis, cellulase secretion was also enhanced in Rut-C30. Both the organisms contained same amounts of intracellular marker enzyme activities (e.g., inosine diphosphatase, thiamine pyrophosphatase, alkaline phosphatase). Finally, the enahncement of secretory activity of Rut-C30 was correlated with the proliferation of rough endoplasmic reticulum (RER) and increased phospholipid content. It appears that Rut-C30 is not only a hypercellulolytic but also a hypersecretor mutant.     

Immunity to Hymenolepis diminuta: unresponsiveness of the athymic nude mouse to infection.

Male and female congenitally athymic nude (nu/nu) mice infected with a single cysticercoid of Hymenolepis diminuta at 6 weeks of age retain the infection for at least 33 days. In the males of their phenotypically normal litter-mates, however, a single cysticercoid infection establishes and grows but is expelled between days 11 and 17. The unresponsiveness of the nude mouse to single H. diminuta infection is evidence that the immune rejection from normal mice is thymus-dependent.     

Synthesis and evaluation of human phosphodiesterases (PDE) 5 inhibitor analogs as trypanosomal PDE inhibitors. Part 1. Sildenafil analogs

Parasitic diseases, such as African sleeping sickness, have a significant impact on the health and well-being in the poorest regions of the world. Pragmatic drug discovery efforts are needed to find new therapeutic agents. In this Letter we describe target repurposing efforts focused on trypanosomal phosphodiesterases. We outline the synthesis and biological evaluation of analogs of sildenafil (1), a human PDE5 inhibitor, for activities against trypanosomal PDEB1 (TbrPDEB1). We find that, while low potency analogs can be prepared, this chemical class is a sub-optimal starting point for further development of TbrPDE inhibitors.