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Henry Hoff

Publications and source records attributed to Henry Hoff.

5 recordsLinked to original sources
PubMed2006

Influenza A virus infection engenders a poor antibody response against the ectodomain of matrix protein 2.

BACKGROUND: Matrix protein 2 (M2) is an integral tetrameric membrane protein of influenza A virus (IAV). Its ectodomain (M2e) shows remarkably little diversity amongst human IAV strains. As M2e-specific antibodies (Abs) have been shown to reduce the severity of infection in animals, M2e is being studied for its capability of providing protection against a broad range of IAV strains. Presently, there is little information about the concentration of M2e-specific Abs in humans. Two previous studies made use of ELISA and Western blot against M2e peptides and recombinant M2 protein as immunosorbents, respectively, and reported Ab titers to be low or undetectable. An important caveat is that these assays may not have detected all Abs capable of binding to native tetrameric M2e. Therefore, we developed an assay likely to detect all M2e tetramer-specific Abs. RESULTS: We generated a HeLa cell line that expressed full length tetrameric M2 (HeLa-M2) or empty vector (HeLa-C10) under the control of the tetracycline response element. These cell lines were then used in parallel as immunosorbents in ELISA. The assay was standardized and M2e-specific Ab titers quantified by means of purified murine or chimeric (mouse variable regions, human constant regions) M2e-specific Abs in the analysis of mouse and human sera, respectively. We found that the cell-based ELISA was substantially more effective than immobilized M2e peptide in detecting M2e-specific Abs in sera of mice that had recovered from repetitive IAV infections. Still, titers remained low (< 5 microg/ml) even after two consecutive infections but increased to approximately 50 microg/ml after the third infection. Competition with free M2e peptide indicated that approximately 20% of M2e-specific Abs engendered by infection reacted with M2e peptide. In humans presenting with naturally acquired influenza virus infection, 11 of 24 paired sera showed a > or = 4-fold increase in M2e-specific Ab titer. The Ab response appeared to be of short duration as titers were very low (average 0.2 mug/ml) in all patients at onset of infection and in controls, in spite of evidence for previous exposure to IAV. CONCLUSION: The results provide convincing evidence that M2e-specific Ab-mediated protection is currently lacking or suboptimal in humans.

Animals↗
PubMed2004

Phospholipids and oxophospholipids in atherosclerotic plaques at different stages of plaque development.

We identified and quantified the hydroperoxides, hydroxides, epoxides, isoprostanes, and core aldehydes of the major phospholipids as the main components of the oxophospholipids (a total of 5-25 pmol/micromol phosphatidylcholine) in a comparative study of human atheroma from selected stages of lesion development. The developmental stages examined included fatty streak, fibrous plaque, necrotic core, and calcified tissue. The lipid analyses were performed by normal-phase HPLC with on-line electrospray MS using conventional total lipid extracts. There was great variability in the proportions of the various oxidation products and a lack of a general trend. Specifically, the early oxidation products (hydroperoxides and epoxides) of the glycerophosphocholines were found at the advanced stages of the plaques in nearly the same relative abundance as the more advanced oxidation products (core aldehydes and acids). The anticipated linear accumulation of the more stable oxidation products with progressive development of the atherosclerotic plaque was not apparent. It is therefore suggested that lipid infiltration and/or local peroxidation is a continuous process characterized by the formation and destruction of both early and advanced products of lipid oxidation at all times. The process of lipid deposition appears to have been subject to both enzymatic and chemical modification of the normal tissue lipids. Clearly, the appearance of new and disproportionate old lipid species excludes randomness in any accumulation of oxidized LDL lipids in atheroma.

Aorta↗
PubMed2003

Downregulation of IRS-1 protein in thapsigargin-treated human prostate epithelial cells.

Thapsigargin treatment of cultured cells leads to an increase in the intracellular calcium concentration, activation of calpain, and, in some cell types, apoptosis. Using a human prostate epithelial cell line that undergoes apoptosis in the presence of thapsigargin, we find decreased levels of IRS-1 protein levels during apoptosis. Inhibition of calpain prevents this decrease in IRS-1 protein; however, inhibitors of caspases or the proteasome are ineffective in maintaining IRS-1 levels. In terms of IGF-I-related second messenger proteins, the effect of thapsigargin is specific for IRS-1 since the protein levels of IGF-I receptor beta-subunit, Akt, Erk, and Shc are not affected. In addition to preventing the reduction in IRS-1, treatment of cells with calpain inhibitor II prevents apoptosis in response to thapsigargin. Finally, IRS-1 and calpain can be identified in protein complexes isolated using IRS-1-specific antibodies, indicating that calpain can associate with either IRS-1 or one of the proteins present in protein complexes that contain IRS-1. In total, these results suggest that IRS-1 may be targeted for degradation by calpain during apoptosis.

Apoptosis↗