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Biomedical subjects

T Braun

Publications and source records attributed to T Braun.

At least 19 recordsLinked to original sources
PubMed2007

NF-kappaB inhibition sensitizes to starvation-induced cell death in high-risk myelodysplastic syndrome and acute myeloid leukemia.

CD34(+) bone marrow blasts from high-risk myelodysplastic syndrome (MDS) patients as well as MDS patient-derived cell lines (P39 and MOLM13) constitutively activate the nuclear factor-kappaB (NF-kappaB) pathway and undergo apoptosis when NF-kappaB is inhibited. Here, we show that the combination of conventional chemotherapeutic agents (daunorubicin, mitoxantrone, 5-azacytidine or camptothecin) with the NF-kappaB inhibitor BAY11-7082 did not yield a synergistic cytotoxicity. In contrast, BAY11-7082 (which targets the NF-kappaB-activating I-kappaB kinase (IKK) complex) or knockdown of essential components of the NF-kappaB system (such as the IKK1 and IKK2 subunits of the IKK complex and the p65 subunit of NF-kappaB), by small interfering RNAs sensitized MDS cell lines to starvation-induced apoptosis. The combination of BAY11-7082 and nutrient depletion synergistically killed the acute myeloid leukemia (AML) cell line U937 as well as primary CD34(+) bone marrow blasts from AML and high-risk MDS patients. The synergistic killing by BAY11-7082, combined with nutrient depletion, led to cell death accompanied by all hallmarks of apoptosis, including an early loss of the mitochondrial transmembrane potential, the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria, activation of caspase-3, phosphatidylserine exposure on the plasma membrane surface and nuclear chromatin condensation. Transmission electron microscopy revealed the presence of numerous autophagic vacuoles in the cytoplasm before cells underwent nuclear apoptosis. Nonetheless, cell death was neither inhibited by the pan-caspase inhibitor z-VAD-fmk nor by knockdown of AIF or of essential components of the autophagy pathway (ATG5, ATG6/Beclin-1, ATG10, ATG12). In contrast, external supply of glucose, insulin or insulin-like growth factor-I could retard the cell death induced by BAY11-7082 combined with starvation. These results suggest that in MDS cells, NF-kappaB inhibition can precipitate a bioenergetic crisis that leads to an autophagic stress response followed by apoptotic cell death.

Acute Disease↗
PubMed2007

Lead exposure and periodontitis in US adults.

BACKGROUND AND OBJECTIVE: Lead is known to have significant effects on bone metabolism and the immune system. This study tested the hypothesis that lead exposure affects periodontitis in adults. MATERIAL AND METHODS: This study used the data from the Third National Health and Nutrition Examination Survey (NHANES III, 1988-94). It analyzed data from 2500 men and 2399 women, 20-56 yr old, who received complete periodontal examination. Periodontitis was defined as the presence of > 20% of mesial sites with >or= 4 mm of attachment loss. Lead exposure was grouped into three categories: < 3; 3-7; and > 7 microg/dL. Covariates were cotinine levels, poverty ratio, race/ethnicity, education, bone mineral density, diabetes, calcium intake, dental visit, and menopause (for women). All analyses were performed separately for men and women and considering the effect design. Univariate, bivariate, and stratified analysis was followed by multivariable analysis by estimating prevalence ratios through poisson regression. RESULTS: After adjustment for confounders, the prevalence ratios, comparing those with a lead blood level of > 7 microg/dL to those with a lead blood level of < 3 microg/dL was 1.70 (95% confidence interval (CI): 1.02, 2.85) for men and 3.80 (95% CI: 1.66, 8.73) for women. CONCLUSION: The lead blood level was positively and statistically associated with periodontitis for both men and women. Considering the public health importance of periodontitis and lead exposure, further studies are necessary to confirm this association.

Adult↗
PubMed2006

Inhibition of NEMO, the regulatory subunit of the IKK complex, induces apoptosis in high-risk myelodysplastic syndrome and acute myeloid leukemia.

In high-risk myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), blasts constitutively activate the antiapoptotic transcription factor nuclear factor-kappaB (NF-kappaB). Here, we show that this NF-kappaB activation relies on the constitutive activation of the IkappaB kinase (IKK) complex, which is formed by the IKKalpha, IKKbeta and IKKgamma/NF-kappaB essential modulator (NEMO) subunits. A cell-permeable peptide that mimics the leucine zipper subdomain of IKKgamma, thus preventing its oligomerization, inhibited the constitutive NF-kappaB activation and induced apoptotic cell death in a panel of human MDS and AML cell lines (P39, MOLM13, THP1 and MV4-11). Small interfering RNA-mediated knockdown of the p65 NF-kappaB subunit or the three IKK subunits including IKKgamma/NEMO also induced apoptotic cell death in P39 cells. Cell death induced by the IKKgamma/NEMO-antagonistic peptide involved the caspase-independent loss of the mitochondrial transmembrane potential as well as signs of outer mitochondrial membrane permeabilization with the consequent release of cytochrome c, apoptosis-inducing factor and endonuclease G. Primary bone marrow CD34(+) cells from high-risk MDS and AML patients also succumbed to the IKKgamma/NEMO-antagonistic peptide, but not to a mutated control peptide. Altogether, these data indicate that malignant cells in high-risk MDS and AML cells critically depend on IKKgamma/NEMO to survive. Moreover, our data delineate a novel procedure for their therapeutic removal, through inhibition of IKKgamma/NEMO oligomerization.

Acute Disease↗
PubMed2006

Activity of thalidomide in patients with platinum-refractory germ-cell tumours.

The aim of this study was assess the activity of thalidomide in patients with progressive relapsed or platinum-refractory germ-cell tumours (GCT). Between April 2002 and January 2003, 15 patients with inoperable progressive GCT were treated with escalated daily doses of 200-600 mg thalidomide. All patients had failed first-line and salvage chemotherapy with a median of 6 (range 4-12) cisplatin-based treatment cycles, 13/15 (87%) patients had received high-dose chemotherapy (HDCT) and 8/15 (53%) patients were considered platinum-refractory or absolute refractory; 8/15 (53%) patients had previously received other palliative chemotherapy regimens. No patient achieved a complete remission (CR) or partial remission (PR). However, 5/15 (33%) patients achieved serological PR and 1 additional patient had stable disease for 3 months. The median duration of remissions was 3 months (range 2-12 months) including 2 patients with a progression-free survival of 9 and 12 months. Responses occurred mainly in patients with a low tumour burden, slow disease progression and alpha-foetoprotein (AFP) elevations. Responses to thalidomide were independent from platinum-sensitivity. Toxicity was mild, with lethargy and constipation in the majority of patients. Skin rash grade II developed in 2 patients and peripheral neurotoxicity grade II/III developed in 4 patients. One responding patient died suddenly from an unknown cause. It is concluded that thalidomide shows single-agent activity in patients with heavily pre-treated GCT, AFP elevations and slowly progressive disease.

Adult↗
PubMed2006

Targeting NF-kappaB in hematologic malignancies.

The transcription factor nuclear factor kappa B (NF-kappaB) can intervene in oncogenesis by virtue of its capacity to regulate the expression of a plethora of genes that modulate apoptosis, and cell survival as well as proliferation, inflammation, tumor metastasis and angiogenesis. Different reports demonstrate the intrinsic activation of NF-kappaB in lymphoid and myeloid malignancies, including preneoplastic conditions such as myelodysplastic syndromes, underscoring its implication in malignant transformation. Targeting intrinsic NF-kappaB activation, as well as its upstream and downstream regulators, may hence constitute an additional approach to the oncologist's armamentarium. Several small inhibitors of the NF-kappaB-activatory kinase IkappaB kinase, of the proteasome, or of the DNA binding of NF-kappaB subunits are under intensive investigation. Currently used cytotoxic agents can induce NF-kappaB activation as an unwarranted side effect, which confers apoptosis suppression and hence resistance to these drugs. Thus, NF-kappaB inhibitory molecules may be clinically useful, either as single therapeutic agents or in combination with classical chemotherapeutic agents, for the treatment of hematological malignancies.

Hematologic Neoplasms↗
PubMed2006

Cytolytic function and survival of natural killer cells are severely altered in myelodysplastic syndromes.

Natural Killer (NK) cells are critical in host defense against malignant transformation and are potent antileukemic cytotoxic effectors. In the present study, we investigated the peripheral NK function in patients with myelodysplastic syndromes (MDS). We demonstrated that the peripheral NK cell population was quantitatively normal in MDS patients. Furthermore, NK cells displayed an expression of the activating natural cytotoxicity receptors (NCR) NKp46 and NKp30 as well as NKG2D similar to that observed in donors, but exert a highly decreased constitutive cytolytic activity compared to resting normal NK cells. Although activation with IL-2 resulted in the upregulation of NKp46 expression by MDS-NK cells, their cytolytic function remained deeply altered as compared to activated donor NK cells. In addition, MDS NK cells did not proliferate in vitro, and displayed an increased rate of apoptosis in response to IL-2 stimulation although the spontaneous apoptosis was not significantly increased. Interestingly, a proportion of peripheral MDS-NK cells were derived from the MDS clone as the cytogenetic anomaly found in bone marrow karyotype was also detected in 20-50% of circulating NK cells. In conclusion, NK cells' cytolytic function and proliferative capacities in response to activation by cytokines are profoundly altered in MDS.

Apoptosis↗
PubMed2005

The 5A structure of heterologously expressed plant aquaporin SoPIP2;1.

SoPIP2;1 is one of the major integral proteins in spinach leaf plasma membranes. In the Xenopus oocyte expression system its water channel activity is regulated by phosphorylation at the C terminus and in the first cytosolic loop. To assess its structure, SoPIP2;1 was heterologously expressed in Pichia pastoris as a His-tagged protein and in the non-tagged form. Both forms were reconstituted into 2D crystals in the presence of lipids. Tubular crystals and double-layered crystalline sheets of non-tagged SoPIP2;1 were observed and analyzed by cryo-electron microscopy. Crystalline sheets were highly ordered and diffracted electrons to a resolution of 2.96A. High-resolution projection maps of tilted specimens provided a 3D structure at 5A resolution. Superposition of the SoPIP2;1 potential map with the atomic model of AQP1 demonstrates the generally well conserved overall structure of water channels. Differences concerning the extracellular loop A explain the particular crystal contacts between oppositely oriented membrane sheets of SoPIP2;1 2D crystals, and may have a function in rapid volume changes observed in stomatal guard cells or mesophyll protoplasts. This crystal packing arrangement provides access to the phosphorylated C terminus as well as the loop B phosphorylation site for studies of channel gating.

Animals↗
PubMed2005

Bak but not Bax is essential for Bcl-xS-induced apoptosis.

Bcl-x(S), a proapoptotic member of the Bcl-2 protein family, is localized in the mitochondria and induces apoptosis in a caspase- and BH3-dependent manner by a mechanism involving cytochrome c release. The way in which Bcl-x(S) induces caspase activation and cytochrome c release, as well as the relationship between Bcl-x(S) and other proapoptotic members of the Bcl-2 family, is not known. Here we used embryonic fibroblasts derived from mice deficient in the multidomain proapoptotic members of the Bcl-2 family (Bax and Bak) and the apoptotic components of the apoptosome (Apaf-1 and caspase-9) to unravel the cascade of events by which Bcl-x(S) promotes apoptosis. Our results show that Bak but not Bax is essential for Bcl-x(S)-induced apoptosis. Bcl-x(S) induced activation of Bak, which in turn promoted apoptosis by apoptosome-dependent and -independent pathways. These findings provide the first evidence that a proapoptotic Bcl-2 family protein induces apoptosis exclusively via Bak.

Animals↗
PubMed2004

Residual tumor resection after high-dose chemotherapy in patients with relapsed or refractory germ cell cancer.

PURPOSE: To assess the role of residual tumor resection performed after high-dose chemotherapy (HDCT) in patients with relapsed or refractory germ cell tumors (GCT). PATIENTS AND METHODS: Between July 1987 and October 1999, postchemotherapy resections of residual tumors were performed in 57 patients who had been treated with HDCT for relapsed or refractory GCT and who had achieved a partial remission to this treatment. RESULTS: Complete resections of residual masses were achieved in 52 (91%) of 57 patients who were rendered disease free; in five (9%) of 57 patients, the resections were incomplete. Resection of a single site was performed in 39 (68%) of 57 patients, and the remaining 18 (32%) of 57 patients required interventions at two or more residual tumor sites. Necrosis was found in 22 (38%) of 57 patients, mature teratoma with or without necrosis was found in nine (16%) of 57 patients, and viable cancer with or without additional necrosis or mature teratoma was found in 26 (46%) of 57 patients. Viable cancer consisted either of residual germ cell or undifferentiated cancer in 22 (85%) of 26 patients, with additional non-GCT histologies in the remaining four patients. Patients with viable cancer had a significantly inferior outcome after surgery compared with patients with necrosis and/or mature teratoma even if all cancer was completely resected. Pulmonary lesions with a diameter of more than 2 cm were the only predictive variable for viable cancer in univariate analysis. CONCLUSION: Resections of all residual tumors should be attempted in patients with relapsed or refractory GCT and partial remissions after HDCT.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2004

The role of high-dose chemotherapy in relapsed germ cell tumors.

Overall, patients with relapsed or progressive germ cell tumors after cisplatin-based chemotherapy have a low chance of cure. Using conventional-dose chemotherapy (CDCT) as salvage treatment, only 15-30% of the patients will become long-term survivors. It is well known that the majority of these patients will ultimately die of their disease. Therefore, improvement of the standard treatment is clearly desirable. In the last years, high-dose chemotherapy (HDCT) has been established as an effective salvage modality. A matched-pair analysis showed an advantage for HDCT compared with CDCT with an improvement in event-free and overall survival. Furthermore, due to increasing clinical experience in the management of side-effects, the use of peripheral blood progenitor cells and the availability of hematopoietic growth factors, HDCT has become relatively safe. Therefore, HDCT should be administered in patients with first relapse and unfavorable prognostic factors, and as second or subsequent salvage treatment followed by complete resections of tumor residuals. Patients with relapse or progressive disease after HDCT who do not qualify for desperation surgery could be salvaged with palliative chemotherapy combinations using gemcitabine, oxaliplatin and paclitaxel. This report reviews the current treatment strategies and recent developments with respect to HDCT given as salvage treatment and discusses the role of prognostic factors in the management of such situations.

Antineoplastic Agents↗
PubMed2004

Continuous telemetric monitoring of fetal oxygen partial pressure during labor.

INTRODUCTION: Upright or ambulatory birth positions are favorable for fetal oxygenation. Studies of fetal oxygenation with regard to maternal position require free maternal mobility. Therefore, telemetry for a fetal sensor for such investigations is a pre-requisite. Telemetry-if technically feasible-could enable monitoring of fetal oxygen partial pressure using an existing sensor without restricting the mobility of the parturient woman. We have developed a telemetry system for use with a fetal transcutaneous partial oxygen pressure sensor (ttcpO(2)) and have studied effects of maternal position and position changes during normal labor. MATERIALS AND METHODS: The monitoring system consists of three parts: the telemetry unit with the ttcpO(2) sensor to transmit the tcpO(2) and the heating output telemetrically, a modified CTG monitor and a personal computer storing the measurements. All data were plotted on the CTG recording paper and fed into a new purpose-designed software, displaying fetal heart rate, the uterine contraction intensity, ttcpO(2) and the heating output. Three laboring women, randomly and successively adopting "classical birth positions" (supine or side positions), sitting or vertical or walking position, were studied. RESULTS: Fetal heart rate, uterine contractions, ttcpO(2) and heating output are influenced by the birth positions and by changes of the birth position. In the classical supine and side position there seemed to be lower fetal oxygenation. Sitting, standing and especially walking were more favorable. DISCUSSION: Telemetry is useful to study a possible clinical benefit of individual birth positions.

Equipment Design↗
PubMed2004

Tacrolimus as monotherapy or combined with minidose methotrexate for graft-versus-host disease prophylaxis after allogeneic peripheral blood stem cell transplantation: long-term outcomes.

We report long-term outcomes for allogeneic peripheral blood stem cell (PBSC) recipients, evaluating cumulative incidence (CI) of acute and chronic graft-versus-host disease (GVHD), after use of tacrolimus with or without minidose methotrexate for GVHD prophylaxis. From April 1996 to April 1998, 97 adults underwent allogeneic PBSC transplantation. The first 49 received tacrolimus monotherapy as GVHD prophylaxis and the subsequent 48 received combination therapy. The median follow-up for survivors was 67 months. Compared to combination therapy, tacrolimus monotherapy resulted in enhanced neutrophil engraftment, shortened hospitalization, comparable rates of GVHD, and equivalent 100-day survival. The CI of grades II-IV acute GVHD was 35% with tacrolimus and 23% with the combination (P=0.19). The CI of III-IV GVHD was 22% for tacrolimus and 19% for the combination. CI of chronic GVHD was similar between the two groups (P=0.5). Patients with good-risk disease had superior overall survival (OS) when compared to those with poor-risk features (P<0.001). Within the good-risk disease category, patients receiving methotrexate had a trend towards improved OS (P=0.07). Multivariate analysis indicated good-risk disease status and methotrexate were independently associated with improved OS, progression-free survival (PFS), and relapse. In addition, patients developing chronic GVHD had a significantly reduced risk of relapse and improved PFS.

Acute Disease↗
PubMed2004

[Pain and ethnicity - results of a survey at three internal/gynecological first-aid stations in Berlin].

QUESTION: How high is the pain pressure in everyday life of German vs. not German patients, with which troubles do they come to the emergency room, how intense is their pain, how long is it lasting, how many pain areas are named? GROUP OF PATIENTS/METHODS: The study "Utilization of clinical emergency rooms by German patients and migrants" was carried out at first-aid stations of three Berlin hospitals in municipal districts with a high share of foreigners in the population in the form of standardized interviews on following topics: roads to have access to the emergency room, perception and interpretation of pain/troubles, expectations from the first-aid station, further medical care, chronical diseases, self-help measures, social data, migration aspects. RESULTS: An everyday life pressure because of headache and rheumatic pains was named significant more often by migrants of Turkish extraction than by the German women asked. In the age-group 50-65 years the migrants chose significant higher scale values to characterize their pain intensity. Migrants named all in all clearly more pain areas than German patients. The share of patients with pain persisting more than three days was 36.1 % in German women, 45.5 % in migrants of Turkish origin, 45.8 % in women of other ethnicity. CONCLUSIONS: Pain interpretation as well as pain expression are socio-culturally conditioned. Differences between migrants and native patients should lead to take more into consideration the concrete life situation and specific strain in the patients' treatment.

Demography↗
PubMed2004

CD20 positive T cell lymphoma: is it a real entity?

CD20+ T cell lymphoma is a rare condition that includes both precursor and peripheral T cell types. However, these cases may be mistaken for T cell marker positive B cell lymphoma, thus creating diagnostic problems with subsequent clinical implications. This report describes a unique case of nodal CD20+ T cell lymphoma with simultaneous cutaneous and subcutaneous involvement. Both nodal and cutaneous lymphomas demonstrated identical monoclonal bands in the T cell receptor rearrangement assay. However, no CD20 expression was demonstrated in the skin lesion. The instability of the CD20 antigen in this tumour may imply that CD20 is not an integral part of the tumour immunophenotype and probably plays no important role in its clinical course. Techniques to avoid misdiagnosis of this lymphoma are discussed.

Aged↗
PubMed2001

Activation of myogenesis by the homeobox gene Lbx1 requires cell proliferation.

Myogenic differentiation can be initiated by a limited number of molecules. In this work, we analyzed the function of the homeobox gene Lbx1 in chicken embryos and explant cultures. We demonstrate that overexpression of Lbx1 in vivo and in vitro leads to a strong activation of various muscle markers. We show that cell proliferation, which is strongly stimulated by Lbx1 and Pax3, is required for Lbx1- or Pax3-dependent myogenic activation. Inhibition of cell proliferation prevents expression of muscle differentiation markers, while the activation of other putative downstream targets of Pax3 and Lbx1 is not affected. Our findings imply that a critical function of Pax3 and Lbx1 during muscle cell formation is the enlargement of muscle cell populations. The growth of the muscle precursor cell population may increase the bias for myogenic differentiation and thus enable myogenic cells to respond to environmental cues.

Animals↗