Elevated levels of circulating tumor necrosis factor alpha in human immunodeficiency virus type 1-infected Africans living in Sweden.

Elevated levels of tumor necrosis factor alpha in serum were found in human immunodeficiency virus type 1 (HIV-1)-infected Africans to a higher extent than in matched HIV-1-infected Caucasians, both groups living in Sweden. The results suggest that factors not related to the environment contribute to enhanced synthesis of tumor necrosis factor alpha in HIV-1-infected patients.     

HIV-1 in Ethiopia: Phylogenetic divergence from other HIV-1 strains

Phylogenetic tree analysis was performed on selected polymerase chain reaction (PCR)-amplified and sequenced regions of the gag and env reading frames of several Ethiopian and Swedish human immunodeficiency virus type 1 (HIV-1) strains. These regions are considered to be conserved parts of the HIV-1 genome and correspond to the p7 of the core (gag) and part of the carboxy terminal of the gp41 protein of env respectively. Comparisons were made with all available HIV-1 sequences.The tree analysis showed that gag sequences from nine and env sequences from four Ethiopian strains all grouped together in separate branches distinct from all other sequenced European, North American, and African HIV-1 isolates. Thus, the Ethiopian strains seem to represent a highly divergent group of HIV-1, which might have developed during a relatively early stage of HIV-1 evolution.     

Sequence analysis of selected regions of theenv (V 3 loop and gp 41) andgag (p 7) reading frames of Ethiopian human immunodeficiency virus type 1 strains

Summary Amplified polymerase chain reaction (PCR) products, corresponding to the V3 loop and gp 41 of theenv, and p 7 of thegag region, from proviral DNA of several Ethiopian and Swedish HIV-1 strains were sequenced. Of the six amino acids (GPGRAF) that constitute the principal neutralizing determinant (PND) within the V 3 loop, the Ethiopian isolates all showed two amino acid changes (GPGQTF). Four to five other substitutions were found in the amino acids flanking the PND. Substitution of alanine (A) for threonine (T) should result in a change in the predicted secondary structure, i.e., disappearance of a coil structure. Percentage similarity data on a stretch of 22 amino acids within the V 3 loop showed a concordance of the Ethiopian HIV-1 isolates with the sequences of published macrophage-T-cell tropic HIV isolates. Additionally derived protein sequences in two other regions showed two common substitutions in p 7 and one to two substitutions in gp 41 compared to a recent consensus sequence. These changes are hitherto unique for the Ethiopian strains, and suggest the presence of a clustering of a divergent HIV-1 strain in Addis Ababa, Ethiopia.     

Response of Ethiopian human immunodeficiency virus type 1 isolates to antiviral compounds.

Human immunodeficiency virus type 1 (HIV-1) isolates of 8 Ethiopian and 8 Swedish untreated AIDS-patients were examined for their sensitivity to 3'-azido-3'-deoxythymidine (AZT), 2',3'-dideoxyinosine (ddI) and leukocyte-derived interferon-alpha (IFN-alpha). No significant difference in drug sensitivity was found between Ethiopian and Swedish isolates, which all were sensitive to AZT, ddI and IFN-alpha except for one Swedish isolate. This isolate exhibited a mutation at amino acid position 215. These results suggest that it should be possible to perform clinical trials in Ethiopia using the same dose regimens as in Sweden.     

Human Primary Cell-Based Organotypic Microtissues for Modeling Small Intestinal Drug Absorption

Purpose

The study evaluates the use of new in vitro primary human cell-based organotypic small intestinal (SMI) microtissues for predicting intestinal drug absorption and drug-drug interaction.

Methods

The SMI microtissues were reconstructed using human intestinal fibroblasts and enterocytes cultured on a permeable support. To evaluate the suitability of the intestinal microtissues to model drug absorption, the permeability coefficients across the microtissues were determined for a panel of 11 benchmark drugs with known human absorption and Caco-2 permeability data. Drug-drug interactions were examined using efflux transporter substrates and inhibitors.

Results

The 3D–intestinal microtissues recapitulate the structural features and physiological barrier properties of the human small intestine. The microtissues also expressed drug transporters and metabolizing enzymes found on the intestinal wall. Functionally, the SMI microtissues were able to discriminate between low and high permeability drugs and correlated better with human absorption data (r²?=?0.91) compared to Caco-2 cells (r²?=?0.71). Finally, the functionality of efflux transporters was confirmed using efflux substrates and inhibitors which resulted in efflux ratios of >2.0 fold and by a decrease in efflux ratios following the addition of inhibitors.

Conclusion

The SMI microtissues appear to be a useful pre-clinical tool for predicting drug bioavailability of orally administered drugs.

     

Interaction of Dendritic Cells with Skin Endothelium: A New Perspective on Immunosurveillance

The goal of this study was to determine the mechanisms by which dendritic cells (DCs) in blood could interact with endothelium, a prerequisite to extravasation into tissues. Our results indicate that DCs express both HECA-452–reactive and nonreactive isoforms of P-selectin glycoprotein ligand 1 (PSGL-1) and can tether and roll efficiently on E- and P-selectin under flow conditions in vitro. Freshly isolated blood DCs were further observed to roll continuously along noninflamed murine dermal endothelium in vivo. This interaction is strictly dependent on endothelial selectins, as shown by experiments with blocking antibodies and with E- and P-selectin–deficient mice. We hypothesize that DCs in blood are constitutively poised at the interface of blood and skin, ready to extravasate upon induction of inflammation, and we showed that cutaneous inflammation results in a rapid recruitment of DCs from the blood to tissues. We propose that this is an important and previously unappreciated element of immunosurveillance.     

Acquired immunodeficiency syndrome: seven cases in an Addis Ababa hospital

7 confirmed cases of Acquired Immune Deficiency Syndrome (AIDS), seen in the Department of Medicine, Yekatit 12 Hospital, Addis Ababa, Nigeria, are presented. These are the 1st cases to be reported in Ethiopia. The ELISA and Western Blot tests were performed at the National Research Institute of Health in Addis Ababa. Attempts to trace possible sexual contacts of 3 cases were unsuccessful. Family members of 2 cases were tested for HIV infection. 3 of the 7 patients presented with tuberculosis, 2 with pneumocystis carinii pneumonia, 1 with generalized lymphadenopathy, and 1 with chronic diarrhea. All had AIDS; 6 of the 7 had 2 major clinical criteria, and all had 2 or more minor clinical criteria. 4 of the patients died. The diagnosis of 7 clinically obvious cases within 1 year in 1 general hospital at a time when it was somewhat difficult to have serological tests performed suggests the urgency of education of hospital workers in the safe handling of blood, blood products and body fluids, and through sterilization of needles and other equipment used by and for all patients.     

Organotypic human oral tissue models for toxicological studies.

Three-dimensional models of the human oral epithelia have been developed to test the irritation of oral-care products and to provide systems to study the pathology of the oral cavity. The in vitro tissue models, cultured using normal oral epithelial cells and serum free medium, adopt a buccal or gingival phenotype. The buccal tissue (designated ORL-200) is 8-12 cell layers thick and non-cornified; the gingival tissue (designated GIN-100) is 9-13 layers thick and cornified at the apical surface. The tissues express cytokeratins 13 and 14 similar to their corresponding native oral tissues. The MTT viability assay was used to assess inter-lot and intra-lot reproducibility. The MTT average intra-lot coefficient of variation (CV) was less than 10% for both tissues and the time required to reduce tissue viability by 50% (ET-50) following application of 1% Triton-X 100 averaged 1.02+/-0.33 h (n=26) and 7.97+/-0.80 h (n=14) for the buccal and gingival tissues, respectively. The utility of the buccal tissue for irritation studies was examined by testing prototype dentifrice formulations and commercially available products including mouthwashes, toothpastes, and oral cleansers. Use of the MTT ET-50 assay and cytokine release clearly differentiated between the formulations and the oral care products. In conclusion, the oral tissue models represent highly reproducible, non-animal means to screen the irritation potential of newly developed oral care products and should be useful to study the innate immunity, biology, and pathology of the oral mucosa.