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Biomedical subjects

Christian Hoffmann

Publications and source records attributed to Christian Hoffmann.

At least 19 recordsLinked to original sources
PubMed2007

Adoptive transfer of syngeneic T cells in HIV-1 discordant twins indicates rapid regulation of T-cell homeostasis.

The safety and efficacy of adoptive T-cell transfer (ATT) was tested in the context of viral suppression in syngeneic twins discordant for human immunodeficiency virus type 1 (HIV-1) infection. Human leucocyte antigen-matched T cells of seven HIV-negative twins were obtained by lymphapheresis and immediately transfused into the HIV-infected sibling. Four twins received 12 ATTs each, with a mean of 2.10 +/- 0.97 x 10(9) CD4(+) T cells and 1.74 +/- 0.81 x 10(9) CD8(+) T cells. Additional transfers were performed in three more twin pairs to study the short-term kinetics of transfused syngeneic T cells. Mean CD4(+) T-cell counts increased significantly, by 0.133 +/- 0.136 x 10(9) cells/l at 1 h and 0.144 +/- 0.12 x 10(9) cells/l at 3 h post-transfusion (P < 0.0001). Short-term kinetic studies suggested a rapid clearance of transferred T cells from the peripheral blood within minutes due to a distribution to marginal pools. After a mean follow up of 39 months, however, a sustained increase of the mean CD4(+) T-cell count was observed (from 0.232 x 10(9) to 0.523 x 10(9) cells/l) without changes of plasma viraemia. We conclude that ATT combined with highly active antiretroviral therapy is safe and leads to a considerable increase in CD4(+) T-cell numbers. The clearance kinetics of the transfused cells from peripheral blood indicates a very rapid regulation of T-cell homeostasis in HIV infection.

Adult↗
PubMed2006

Interferometric biosensor based on planar optical waveguide sensor chips for label-free detection of surface bound bioreactions.

A label free optical biosensor based on a free-space Young interferometer configuration is presented. Commercial planar Ta(2) O(5) waveguides are used as sensing elements and allow the investigation of surface bound bioreactions like immunoreactions or biological affinity systems. Design criteria are discussed and a detailed characterization of the sensor performance is presented. The developed interferometer yields an effective refractive index resolution of 9 x 10(-9), corresponding to a surface coverage of approximately 13 fg/mm(2). The performance of the system is characterized by two different affinity systems: the antibody-antigen complex protein G-immunoglobulin G is used as a model system for monitoring reaction kinetics. Further measurements on a silanized surface show the formation of a streptavidin monolayer on a biotinylated surface.

Biosensing Techniques↗
PubMed2006

Combination of tenofovir and lamivudine versus tenofovir after lamivudine failure for therapy of hepatitis B in HIV-coinfection.

OBJECTIVE: At present sequential monotherapy for chronic hepatitis B with hepatitis B virus (HBV)-polymerase inhibitors is clinical practice. It is unknown to date whether combination therapy with lamivudine plus tenofovir could be superior to sequential therapy with tenofovir after the occurrence of lamivudine resistance. METHODS: We conducted a multicenter, 1: 2 matched pair analysis comparing patients with HBV/HIV-coinfection starting an antiretroviral regimen including tenofovir plus lamivudine with patients who had highly replicative, lamivudine resistant HBe-antigen positive chronic hepatitis B and started with tenofovir as the only active HBV polymerase inhibitor subsequent to lamivudine. RESULTS: At baseline patients on tenofovir plus lamivudine (n = 25) had a median HBV DNA of 5.9 x 10(7) copies/ml compared to 1.37 x 10(8) copies/ml in the tenofovir arm (n = 50; P = 0.32). A sustained undetectable HBV DNA < 1000 copies/ml was achieved in 19/25 (76%) patients on tenofovir plus lamivudine and in 42/50 (84%) on tenofovir (P = 0.53). A loss of HBe-antigen was observed in 9/25 (36%) patients on tenofovir plus lamivudine and in 12/50 (24%) patients on tenofovir (P = 0.29). HBs-antigen loss was found in 1/25 (4%) and 3/50 (6%) patients. CONCLUSIONS: In this cohort of HBV/HIV-coinfected individuals, full HBV DNA suppression was achieved in the majority of patients independent of treatment allocation. Loss of HBe- and HBs-antigen was not different between the two study arms. Over a median treatment period of 116 weeks tenofovir was as effective as tenofovir plus lamivudine. Longer treatment periods may be needed to evaluate potential benefits of first-line combination therapy for chronic hepatitis B.

Adenine↗
PubMed2006

High serum urate in HIV-infected persons: the choice of the antiretroviral drug matters.

Data with regard to serum uric acid levels in HIV-infected subjects are scarce. A high prevalence of hyperuricaemia was identified in a prospective analysis of urate levels in 2287 visits made by a cohort of 270 HIV-positive patients. In univariate and multivariate analysis, hyperuricaemia was associated with factors previously identified in HIV-uninfected individuals, but also with the use of some antiretroviral drugs, particularly with the use of stavudine.

Adult↗
PubMed2006

Successful autologous stem cell transplantation in a severely immunocompromised patient with relapsed AIDS-related B-cell lymphoma.

There is now evidence that the tolerability and response to systemic chemotherapy in HIV-infected patients with AIDS-related lymphoma (ARL) is significantly improved by highly active antiretroviral therapy. Here we report an severely immunocompromised AIDS patient with recurrent ARL who was successfully treated with autologous stem cell transplantation (ASCT). We also review the current literature of ASCT in HIV-infected patients.

Adult↗
PubMed2006

AIDS-associated Burkitt or Burkitt-like lymphoma: short intensive polychemotherapy is feasible and effective.

The objective was to evaluate the feasibility and efficacy of a short-term, multi-agent and dose intensive regimen in AIDS patients with Burkitt or Burkitt-like lymphoma (BL/BLL) and to compare its efficacy with that of a conventional regimen. This was a retrospective, multi-center cohort study of all HIV-1-infected patients diagnosed with BL/BLL between 1990 - 2004. Patients were assigned to two different chemotherapy approaches. Group A received a protocol which was adapted from the German multi-center study group for adult acute lymphoblastic leukemia (GMALL). Group B received a conventional CHOP-based chemotherapy. Fifty-one patients were included in the analysis. In group A (n = 20), significantly more patients achieved complete remission (75% vs 40%, P = 0.02) than in group B (n = 31). One-year survival in group A was 65% compared to 44% in group B (P = 0.17). In a multi-variable Cox regression analysis, treatment according to the GMALL protocol was significantly associated with prolonged survival with a relative hazard rate of 0.13 (95% CI 0.03 - 0.63, P = 0.01). In conclusion, the short and intensive GMALL protocol for B-ALL/NHL is feasible in patients with AIDS-BL/BLL. Outcome may be improved compared to patients treated with CHOP-based regimens. In the era of HAART, more intensive chemotherapy regimens should be considered in patients with highly aggressive lymphomas.

Adult↗
PubMed2005

Integration site selection by HIV-based vectors in dividing and growth-arrested IMR-90 lung fibroblasts.

DNA integration is a defining step in the retroviral life cycle and the basis of stable gene transfer in retrovirus-based gene therapy. Previous studies of integration by HIV-based vectors have shown that integration is not random, but favored in active transcription units. Studies to date have focused on HIV integration in dividing cells, leaving open the question of whether integration target site selection might differ in nondividing cells. According to one idea, division of the host cell might be required for favored integration in transcription units, possibly as a result of chromatin remodeling during DNA replication. Here we have investigated this issue by comparing integration in dividing IMR-90 primary lung fibroblasts to integration in nondividing IMR-90 cells arrested in G1 by serum starvation and contact inhibition. We identified several differences in integration site selection in arrested versus dividing cells, including the frequency of integration in transcription units and in gene-rich regions. However, integration in nondividing cells was in fact more favored in transcription units, contrary to the idea that cell division was important for this bias. These data provide the first view of lentiviral integration in nondividing cells and help constrain models for the mechanism of favored integration in genes.

Cell Division↗
PubMed2005

A role for LEDGF/p75 in targeting HIV DNA integration.

HIV DNA integration is favored in active genes, but the underlying mechanism is unclear. Cellular lens epithelium-derived growth factor (LEDGF/p75) binds both chromosomal DNA and HIV integrase, and might therefore direct integration by a tethering interaction. We analyzed HIV integration in cells depleted for LEDGF/p75, and found that integration was (i) less frequent in transcription units, (ii) less frequent in genes regulated by LEDGF/p75 and (iii) more frequent in GC-rich DNA. LEDGF is thus the first example of a cellular protein controlling the location of HIV integration in human cells.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Mixed self-assembled monolayers (SAMs) consisting of methoxy-tri(ethylene glycol)-terminated and alkyl-terminated dimethylchlorosilanes control the non-specific adsorption of proteins at oxidic surfaces.

Monolayers from the newly synthesized compound methoxy-tri(ethylene glycol)-undecenyldimethylchlorosilane (CH3O(CH2CH2O)3(CH2)11Si(CH3)2Cl, MeO(EG)3C11DMS) and dodecyldimethylchlorosilane (DDMS), both pure and mixed, were prepared by self-assembly from organic solution in the presence of an organic base. The films obtained were characterized by advancing and receding contact angle measurements and ellipsometry to confirm the formation of self-assembled monolayers (SAMs). The resulting data on the covalently attached dimethylsilanes were compared to known oligo(ethylene glycol) (OEG)-terminated SAM systems based on terminal alkenes, thiolates or trihydrolyzable silanes. The composition of the mixed SAMs was found to depend directly and linearly on the composition of the silanization solution. Enhanced protein repellent properties were found for the SAMs using a variety of proteins, including the Ras Binding Domain (RBD), a protein with high relevance for cancer diagnostics. Roughly a RBD protein monolayer amount was adsorbed to silicon oxide surfaces silanized with DDMS or non-silanized silicon wafers, and in contrast, no RBD was adsorbed to surfaces silanized with MeO(EG)3C11DMS or to mixed monolayers consisting of DDMS and MeO(EG)3C11DMS if the content of OEG-silane overcame a critical content of X(EG) approximately 0.9.

Adsorption↗
PubMed2005

AIDS-related B-cell lymphoma (ARL): correlation of prognosis with differentiation profiles assessed by immunophenotyping.

This study was undertaken to analyze the differentiation profiles assessed by immunophenotyping in AIDS-related B-cell lymphoma (ARL) and their relation to the clinical course. Paraffin-embedded sections of 89 ARL cases during 1989 to 2004 were stained immunohistochemically with antibodies to CD3, CD10, CD20, CD38, CD138/Syndecan-1 (Syn-1), multiple myeloma-1/interferon regulatory factor-4 (MUM1/IRF4), B-cell lymphoma protein-2 (BCL-2), BCL-6, latent membrane protein-1 (LMP-1), and Ki-67. Expression of CD10 and CD20 were associated with better overall survival (OS; P = .009 and P = .04, respectively). Expression of CD20 was associated with longer disease-free survival (DFS; P = .03), whereas expression of CD138/Syn-1 was associated with shorter DFS (P = .03). OS and DFS were worse in patients with immunophenotypic profiles related to post-germinal center (GC) differentiation (BCL-6 and CD10 negative, MUM1/IRF4 and/or CD138/Syn-1 positive) when compared with GC differentiation (P = .01). When controlled for age-adjusted International Prognostic Index (IPI), prior AIDS-defining illness (ADI), and year of ARL diagnosis, a post-GC differentiation remained significantly associated with poor OS and DFS. Expression of CD10 was associated with a preserved immunocompetence, whereas CD20 was less frequent in patients developing ARL while on highly active antiretroviral therapy (P = .04). In summary, lack of CD20 or CD10 expression and a post-germinal center signature are associated with a worse prognosis in ARL.

Adult↗
PubMed2005

[Premature arteriosclerosis in HIV-infected patients? Current status].

Complex lipodystrophic body changes in association with metabolic abnormalities such as dyslipidemia and insulin resistance have become a common feature in HIV patients on highly active antiretroviral therapy (HAART). If these metabolic changes will lead to an epidemic of cardiovascular events within the next decades, however, remains to be seen. The incidence of myocardial infarctions in HIV-infected patients continues to be low. Current data on changes of the incidence in the HAART era remains somewhat conflicting, probably due to methodological issues. In this review the key studies concerning the incidence of premature arteriosclerosis in HIV-infected patients are discussed.

Antiretroviral Therapy, Highly Active↗
PubMed2005

Genome-wide analysis of retroviral DNA integration.

Retroviral vectors are often used to introduce therapeutic sequences into patients' cells. In recent years, gene therapy with retroviral vectors has had impressive therapeutic successes, but has also resulted in three cases of leukaemia caused by insertional mutagenesis, which has focused attention on the molecular determinants of retroviral-integration target-site selection. Here, we review retroviral DNA integration, with emphasis on recent genome-wide studies of targeting and on the status of efforts to modulate target-site selection.

Animals↗
PubMed2005

Presence of broadly reactive and group-specific neutralizing epitopes on newly described isolates of Crimean-Congo hemorrhagic fever virus.

Crimean-Congo hemorrhagic fever virus (CCHFV), a member of the genus Nairovirus of the family Bunyaviridae, causes severe disease in humans with high rates of mortality. The virus has a tripartite genome composed of a small (S), a medium (M) and a large (L) RNA segment; the M segment encodes the two viral glycoproteins, G(N) and G(C). Whilst relatively few full-length M segment sequences are available, it is apparent that both G(N) and G(C) may exhibit significant sequence diversity. It is unknown whether considerable antigenic differences exist between divergent CCHFV strains, or whether there are conserved neutralizing epitopes. The M segments derived from viral isolates of a human case of CCHF in South Africa (SPU 41/84), an infected tick (Hyalomma marginatum) in South Africa (SPU 128/81), a human case in Congo (UG 3010), an infected individual in Uzbekistan (U2-2-002) and an infected tick (Hyalomma asiaticum) in China (Hy13) were sequenced fully, and the glycoproteins were expressed. These novel sequences showed high variability in the N-terminal region of G(N) and more modest differences in the remainder of G(N) and in G(C). Phylogenetic analyses placed these newly identified strains in three of the four previously described M segment groups. Studies with a panel of mAbs specific to G(N) and G(C) indicated that there were significant antigenic differences between the M segment groups, although several neutralizing epitopes in both G(N) and G(C) were conserved among all strains examined. Thus, the genetic diversity exhibited by CCHFV strains results in significant antigenic differences that will need to be taken into consideration for vaccine development.

Animals↗
PubMed2005

The growth rate of Mycobacterium smegmatis depends on sufficient porin-mediated influx of nutrients.

Mycobacteria have a unique outer membrane (OM) that is thicker than any other known biological membrane. Nutrients cross this permeability barrier by diffusion through porins. MspA is the major porin of Mycobacterium smegmatis. In this study we showed that three paralogues of MspA, namely MspB, MspC and MspD are also porins. However, only the mspA and mspC genes were expressed in the wild-type strain. None of the single deletion mutants displayed a significant OM permeability defect except for the mspA mutant. Deletion of the mspA gene caused activation of transcription of mspB and/or mspD in three independent strains by unknown chromosomal mutations. It is concluded that mspB and mspD provide backup porins for M. smegmatis. This also indicated that a minimal porin-mediated OM permeability is essential for survival of M. smegmatis. Electron microscopy in combination with quantitative image analysis of protein gels revealed that the number of pores per cell dropped from 2400 to 800 and 150 for the DeltamspA and DeltamspA DeltamspC mutant (ML10) respectively. The very low number of pores correlated well with the at least 20-fold lower channel activity of detergent extracts of the ML10 strain and its 15- and 75-fold lower permeability to nutrient molecules such as serine and glucose respectively. The amount of Msp porin and the OM permeability of the triple porin mutant lacking mspA, mspC and mspD was not altered. The growth rate of M. smegmatis dropped drastically with its porin-mediated OM permeability in contrast to porin mutants of Escherichia coli. These results show that porin-mediated influx of nutrients is a major determinant of the growth rate of M. smegmatis.

Anti-Bacterial Agents↗
PubMed2005

Malignant melanoma and HIV infection -- aggressive course despite immune reconstitution.

BACKGROUND: Highly active antiretroviral therapy (HAART) has altered the course of most AIDS-related malignancies. There is some evidence that cellular immunity plays an important role in the progression of metastatic melanoma. CASE REPORT: We report on a patient suffering from metastatic melanoma and HIV infection. The 53-year-old man received HAART in order to use both its anti-tumor efficacy and its stimulating effect on cellular and humoral immune functions. Furthermore, our patient was treated with interleukin-2, a drug which has shown efficacy in metastatic melanoma and HIV infection. RESULTS: Although the CD4 and CD8 cell count increased significantly, a fulminant progression of melanoma in the liver and spleen was noted, and the patient died subsequently. CONCLUSION: This case describes that neither immune reconstitution through HAART nor interleukin-2 treatment were able to lead into an anti-tumor response. HIV-infected patients should be monitored routinely for an early diagnosis of this potentially lethal disease.

Anti-HIV Agents↗
PubMed2004

Progressive multifocal leukencephalopathy in patients on highly active antiretroviral therapy: survival and risk factors of death.

OBJECTIVE: To describe the clinical course and risk factors of death in highly active antiretroviral therapy (HAART)-treated patients with progressive multifocal leukencephalopathy (PML); to evaluate the efficacy of cidofovir in addition to HAART. METHODS: Retrospective multicenter cohort study of PML in HIV-1-infected patients. Diagnosis of PML was confirmed by histology or by positive polymerase chain reaction for JC virus (JCV) in cerebrospinal fluid (CSF) or was made by typical radiologic and clinical findings. RESULTS: Thirty-five cases of PML were identified. The diagnosis was made by histology (9 cases), detection of JCV in CSF (17 cases), and by radiologic findings (9 cases). Upon manifestation of PML, 15/35 patients had never received HAART, and 11/35 were on HAART for >6 months (median 1126 days). In 9/35 cases, clinical manifestation of PML occurred within 6 months after initiation of HAART. All patients received HAART after PML diagnosis. After a median follow-up of 553 days (range 28-2694 days), the median survival time was not reached. In 12 patients who were treated concomitantly with cidofovir, cumulative survival was significantly shorter than in patients without cidofovir (P = 0.03). Patients in whom PML was diagnosed while on HAART demonstrated a trend toward a shorter survival than HAART-naive patients (P = 0.15). CONCLUSIONS: PML continues to occur in HIV-1-infected patients even when they are treated with HAART. Patients developing PML on HAART had a trend toward a shorter median survival compared with treatment-naive patients, and cidofovir therapy was not associated with improved survival in this cohort.

Acquired Immunodeficiency Syndrome↗