Acquired immunodeficiency syndrome of childhood

AIDS of childhood is reviewed in this timely article, including care of the child with infectious complications, and other current and future management concerns.     

Lithium stimulation of murine hematopoiesis in liquid culture: an effect mediated by marrow stromal cells

Lithium has previously been observed to stimulate in vitro Dexter culture hemopoiesis with increases in granulocytes, megakaryocytes, and pluripotent stem cells (CFU-S). In the present study, a two-phase murine Dexter culture system was established to study the mechanism of lithium-mediated stem cell stimulation. Different lots of horse sera or fetal calf sera were found to have markedly different effects on Dexter culture growth; given the appropriate sera supplementation, supernatant cells from Dexter cultures established from C57BL/6J mice 3 wk previously were free of stromal-forming capacity, but had stem cells and could grow on 900-950 R irradiated stroma. Conversely, in vitro irradiation (900-950 R) of 3-wk cultures resulted in a stem-cell-free adherent monolayer that could support growth for up to 9 wk in culture. The stroma from Dexter cultures preexposed to lithium chloride (1.0 mmole/liter) for 3 wk, irradiated (900 R), and then refed with 3-wk Dexter supernatant cells has an enhanced capacity to support cell production, CFU-S, and probably granulocyte-macrophage colony-forming cell (GM-CFU-C) production, as compared to stroma not preexposed to lithium. Lithium carryover was ruled out in these experiments. These data indicate that lithium stimulates CFU-S and in vitro granulopoiesis by an indirect effect on a radioresistant adherent stromal cell.     

Activity of human trypanosome lytic factor in mice

The inability of the cattle pathogen Trypanosoma brucei brucei to infect humans is due to an innate factor in human serum termed Trypanosome Lytic Factor (TLF). Human haptoglobin-related protein is the proposed toxin in TLF and can exist either as a component of a minor subclass of high-density lipoprotein (TLF-1) or as a lipid free, high molecular weight protein complex (TLF-2). The trypanolytic activity of both TLF-1 and TLF-2 has been studied in vitro but their relative contributions to protection against T. b. brucei infection in vivo has not been established. In the present studies we show that treatment of T. b. brucei infected mice with TLF-1 resulted in a dose dependent decrease in parasite numbers but did not affect parasite numbers in mice infected with Trypanosoma brucei rhodesiense, the causative agent of the human sleeping sickness. Similarly, pretreatment of mice with TLF-1 resulted in protection against a challenge by T. b. brucei but had no effect on T. b. rhodesiense challenge. Induction of the acute phase protein haptoglobin, a natural antagonist of TLF-1, diminished but did not abolish the protection against trypanosome challenge. In addition, haptoglobin knockout mice showed higher levels of TLF-1 mediated protection against a T. b. brucei challenge. These results suggest that while TLF-1 is active in vivo, even in the presence of elevated levels of haptoglobin, its activity is modulated in a dose dependent fashion by haptoglobin in the circulation.     

In vitro and in vivo neutralization of the relapsing fever agent Borrelia hermsii with serotype-specific immunoglobulin M antibodies

The antigenic variation of the relapsing fever agent Borrelia hermsii is associated with changes in the expression of the Vlp and Vsp outer membrane lipoproteins. To investigate whether these serotype-defining proteins are the target of a neutralizing and protective antibody response, monoclonal antibodies were produced from spleens of infected mice just after clearance of serotype 7 cells from the blood. Two immunoglobulin M monoclonal antibodies, H7-7 and H7-12, were studied in detail. Both antibodies specifically agglutinated serotype 7 cells and inhibited their growth in vitro. Administered to mice before or after infection, both antibodies provided protection against infection or substantially reduced the number of spirochetes in the blood of mice after infection. Whereas antibody H7-12 bound to Vlp7 in Western blotting, enzyme-linked immunosorbent assay, and immunoprecipitation assays, as well as to whole cells in other immunoassays, antibody H7-7 only bound to wet, intact cells of serotype 7. Antibody H7-7 selected against cells expressing Vlp7 in vitro and in vivo, an indication that Vlp7 was a conformation-sensitive antigen for the antibody. Vaccination of mice with recombinant Vlp7 with adjuvant elicited antibodies that bound to fixed whole cells of serotype 7 and to Vlp7 in Western blots, but these antibodies did not inhibit the growth of serotype 7 in vitro and did not provide protection against an infectious challenge with serotype 7. The study established that a Vlp protein was the target of a neutralizing antibody response, and it also indicated that the conformation and/or the native topology of Vlp were important for eliciting that immunity.     

The laboratory assessment of enamel erosion: a review

Objectives. To review the various methods and techniques available to assess enamel erosion in vitro.

Data. Peer reviewed scientific articles.

Sources. Medline and Web of Science searches and manual searching.

Study selection. Laboratory based assessments only included.

Conclusions. A number of macroscopic and microscopic techniques have been used to assess enamel erosion in vitro and in situ. This review examines techniques which are either well established or comparatively novel techniques that are being explored for their potential.     

Screening of selected indigenous plants of Lebanon for antimicrobial activity

The objective of this study is to test in vitro the antimicrobial efficacy of 39 water and 39 methanol extracts derived from different parts of 27 indigenous wild plant species that have been commonly used in Lebanese folk medicine. The antimicrobial efficacy was determined using the single disk diffusion method, with 10 and 20 microl load extract volume per disc. Nine test microorganisms were used namely, Escherichia coli, Proteus sp., Pseudomonas aeruginosa, Shigella dysenteria, Salmonella enteritidis, Salmonella typhi, Staphylococcus aureus, Streptococcus faecalis, and Candida albicans. Only one water extract out of 39 derived from whole plant of Alchemilla diademata showed an antimicrobial activity against Staphylococcus aureus. The percentage of test organisms that were susceptible to 10 most efficacious methanol plant extracts (20 microl/disc) were as follows: Achillea damascena whole plant (88.8%), Anthemis scariosa flower (88.8%), Cirsium sp. whole plant (88.8%), Centaurea ainetensis flowers (88.8%), Hieracium sp. whole plant (88.8%), Origanum libanoticum whole plant (99.9%), Ranunculus myosuroudes whole plant (88.8%), Nepata curviflora leaf (88.8%), Nepata curviflora stem, and Verbascum leptostychum flower (99.9%). The minimum inhibitory concentration (MIC) was determined on plant extracts that showed high efficacy against the test organisms. The chance to find antimicrobial activities was more apparent in methanol rather than water extracts of the same indigenous plants of Lebanon, with higher antimicrobial activities in 20 microl methanol extract-discs in comparison to that present in the 10 microl discs (P < 0.05).