AIDS vaccination studies using an ex vivo feline immunodeficiency virus model: failure to protect and possible enhancement of challenge infection by four cell-based vaccines prepared with autologous lymphoblasts

Immunogenicity and protective activity of four cell-based feline immunodeficiency virus (FIV) vaccines prepared with autologous lymphoblasts were investigated. One vaccine was composed of FIV-infected cells that were paraformaldehyde fixed at the peak of viral expression. The other vaccines were attempts to maximize the expression of protective epitopes that might become exposed as a result of virion binding to cells and essentially consisted of cells mildly fixed after saturation of their surface with adsorbed, internally inactivated FIV particles. The levels of FIV-specific lymphoproliferation exhibited by the vaccinees were comparable to the ones previously observed in vaccine-protected cats, but antibodies were largely directed to cell-derived constituents rather than to truly viral epitopes and had very poor FIV-neutralizing activity. Moreover, under one condition of testing, some vaccine sera enhanced FIV replication in vitro. As a further limit, the vaccines proved inefficient at priming animals for anamnestic immune responses. Two months after completion of primary immunization, the animals were challenged with a low dose of homologous ex vivo FIV. Collectively, 8 of 20 vaccinees developed infection versus one of nine animals mock immunized with fixed uninfected autologous lymphoblasts. After a boosting and rechallenge with a higher virus dose, all remaining animals became infected, thus confirming their lack of protection.     

Homologous recombination: from model organisms to human disease

Recent experiments show that properly controlled recombination between homologous DNA molecules is essential for the maintenance of genome stability and for the prevention of tumorigenesis.     

Extracellular calcium affects the membrane currents of cultured human keratinocytes.

Electrophysiologic properties of cultured human keratinocytes were studied using the patch voltage-clamp technique. Undifferentiated, proliferative keratinocytes grown in low Ca2+ medium had an average resting membrane potential of -24 mV. Voltage-clamp experiments showed that these cells had two membrane ionic currents: a large voltage-independent leak conductance, and a smaller voltage-dependent Cl- current that activated with depolarization. Increasing the extracellular Ca2+ concentration from 0.15 to 2 mM resulted in a doubling of the magnitude of the voltage-gated current and a shift in current activation to more negative potentials. Since levels of extracellular Ca2+ can alter the morphology and differentiation state of keratinocytes, the finding of a Ca2(+)-activated Cl- current in these cells suggests a role for this conductance in the initiation of differentiation.     

New cyclic peptide proteasome inhibitors

Here we report the study of a new series of vinyl ester cyclopeptide analogues synthesized on the basis of our previous development of a class of cyclopeptides derived from our linear prototype inhibitors. In these compounds, the exocyclic pharmacophoric unit Leu-VE was linked to the γ-carboxyl group of the glutamic acid residue at the C-terminal. The best analogues of the series have been shown to inhibit the caspase-like activity of the proteasome at nanomolar concentrations and have also demonstrated good resistance to proteolysis and a capacity to permeate the cell membrane.     

1-Naphthol basic dye (1-NBD). An alternative to diaminobenzidine (DAB) in immunoperoxidase techniques

The usefulness of 1-naphthol as substrate for horseradish peroxidase (HRP) in immunohistochemistry was studied using the peroxidase-antiperoxidase (PAP) and avidin-biotin-complex (ABC) methods in the demonstration of glial fibrillary acidic protein (GFAP), vimentin, carbonic anhydrase C (CA.C), and factor VIII-related antigen (FVIII/RAg) in central nervous tissue and cerebral tumors. In the presence of ammonium carbonate, 1-naphthol is oxidized by HRP and hydrogen peroxide, producing a fine gray-violet precipitate. The oxidation product of 1-naphthol proved capable of binding a great number of basic dyes. For each stain the final reaction product had a characteristic color that was different from the spontaneous color of the dye and from the color displayed by nuclei. The final color obtained with this procedure was alcohol resistant and could be mounted in solvent-based mounting media. The results obtained with the 1-naphthol basic dye (1-NBD) method were compared with those obtained using the diaminobenzidine (DAB) reaction in the demonstration of GFAP-positive astrocytes. The DAB reaction produced a more intense staining but also a coarser precipitate than the 1-NBD reaction. The 1-NBD procedure showed more morphological detail of fine structures and did not obscure nuclei and mitosis. The very low toxicity of 1-naphthol compared with DAB (a suspected carcinogen) is an important advantage of the 1-NBD method, as is its high specificity and sensitivity.     

Toward molecular electronics

One-dimensional polyelectrolytes are proposed as molecular devices based on soliton propagation. The use of such “molecular wires” as delay lines or shift registers raises the problem of their electrical screening, because, when a large number of these wires are densely packed, cross-talking between them might occur. In order to overcome such a drawback, a detailed study of the polyelectrolyte behavior in an ionic solution has been developed, under equilibrium conditions. The results bring into evidence a condensation process, around each molecular wire, of the mobile ions in the solution. The consequent self-screening effect could be relevant in reducing cross-talking.     

Optimal design of airlift fermenters

In this article a modeling of a draft-tube airlift fermentor (ALF) based on perfect backmixing of liquid and plugflow for gas bubbles has been carried out to optimize the design and operation of fermentation units at different working capacities. With reference to a whey fermentation by yeasts the economic optimization has led to a slim ALF with an aspect ration of about 15. As far as power expended per unit of oxygen transfer is concerned, the responses of the model are highly influenced by k_La However, a safer use of the model has been suggested in order to assess the feasibility of the fermentation process under study.