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K Lehmann

Publications and source records attributed to K Lehmann.

At least 19 recordsLinked to original sources
PubMed2001

Analysis of the transcriptional program induced by Raf in epithelial cells.

Activation of the Raf/MAP kinase pathway is a critical event in tumorigenesis induced by RAS and other oncogenes, a major role of this signaling system being the regulation of cellular transcription factors. To address the contribution of MAP kinase mediated transcriptional changes to the transformed phenotype, we used an inducible form of Raf to analyze early changes in the transcription of some 6000 genes following activation of the kinase in a normal human breast epithelial cell line. Of the more than 120 significant changes in mRNA level detected, genes promoting cell proliferation, invasiveness, and angiogenesis featured prominently. Some of the most strongly induced genes encoded growth factors of the EGF family: Autocrine activation of the EGF receptor was shown to be responsible for the ability of Raf activation to protect these cells from apoptosis induced by detachment of cells from extracellular matrix (anoikis), which is a critical component of the transformed phenotype.

Apoptosis↗
PubMed2001

Prospective detection of clinically relevant prostate cancer in the prostate specific antigen range 1 to 3 ng./ml. combined with free-to-total ratio 20% or less: the Aarau experience.

PURPOSE: Little is known about the incidence rate and clinical relevance of prostate cancer in a low prostate specific antigen (PSA) level. In a prospective PSA based screening study we investigated the incidence and clinicopathological features of prostate cancer that occurred within PSA range 1 to 3 ng./ml. when the free-to-total ratio was 0.20 or less. MATERIALS AND METHODS: Men participating in the Aarau, Switzerland, section of the European Randomized Study of Screening for Prostate Cancer between October 1998 and July 2000 were included in the study. As a side study, all men with PSA between 1 and 3 ng./ml. and free-to-total ratio 0.20 or less were invited to undergo further evaluation with ultrasound guided sextant prostate biopsy. RESULTS: Overall, 168 (7.8%) participants fulfilled inclusion criteria. A total of 158 (94%) patients underwent prostate biopsy, and prostate cancer was detected in 17 (10.8%). There were no statistically significant differences between prostate cancer and benign prostatic hyperplasia in regard to patient age (60.7 versus 59.8 years), prostate volume (23.9 versus 23.0 cc), PSA (1.98 versus 1.86 ng./ml.), free-to-total ratio (0.161 versus 0.160), PSA density (0.089 versus 0.076 ng./ml.) or PSA transition zone density (0.33 versus 0.24 ng./ml., respectively). Median Gleason score was 5 on prostate biopsy versus 6 on retropubic prostatectomy specimen. Of the 14 patients who underwent surgery there were positive lymph nodes in 1, stage pT3b Gleason 7 disease in 1, and pathologically organ confined Gleason 5 in 2, Gleason 6 in 5 and Gleason 7 in 5. Mean tumor volume was 1.01 cc (range 0.02 to 5.17). There were 2 (14.3%) insignificant (less than 0.2 cc, Gleason grade 3 or less), 1 (7.1%) minimal (less than 0.5cc, Gleason grade 3 or less) and 11 (78.6%) clinically relevant and potentially harmful cancers. CONCLUSIONS: There is a significant number of prostate cancer cases diagnosed at PSA as low as 1 to 3 ng./ml. A majority of these tumors are clinically significant. This free-to-total ratio range may be helpful for identifying prostate cancer. The "window of opportunity" for detection of curable cancer may change in populations with higher life expectancy towards lower PSA. Lack of specificity and characterization of tumor aggressiveness remains an unsolved issue for PSA.

Aged↗
PubMed2001

Tomato ribonuclease LX with the functional endoplasmic reticulum retention motif HDEF is expressed during programmed cell death processes, including xylem differentiation, germination, and senescence.

We have studied the subcellular localization of the acid S-like ribonuclease (RNase) LX in tomato (Lycopersicon esculentum Mill.) cells using a combination of biochemical and immunological methods. It was found that the enzyme, unexpectedly excluded from highly purified vacuoles, accumulates in the endoplasmic reticulum. The evidence that RNase LX is a resident of the endoplasmic reticulum (ER) is supported by an independent approach showing that the C-terminal peptide HDEF of RNase LX acts as an alternative ER retention signal in plants. For functional testing, the cellular distribution of chimeric protein constructs based on a marker protein, Brazil nut (Bertholletia excelsa) 2S albumin, was analyzed immunochemically in transgenic tobacco (Nicotiana tabacum) plants. Here, we report that the peptide motif is necessary and sufficient to accumulate 2S albumin constructs of both vacuolar and extracellular final destinations in the ER. We have shown immunochemically that RNase LX is specifically expressed during endosperm mobilization and leaf and flower senescence. Using immunofluorescence, RNase LX protein was detected in immature tracheary elements, suggesting a function in xylem differentiation. These results support a physiological function of RNase LX in selective cell death processes that are also thought to involve programmed cell death. It is assumed that RNase LX accumulates in an ER-derived compartment and is released by membrane disruption into the cytoplasma of those cells that are intended to undergo autolysis. These processes are accompanied by degradation of cellular components supporting a metabolic recycling function of the intracellular RNase LX.

Amino Acid Motifs↗
PubMed2000

Raf induces TGFbeta production while blocking its apoptotic but not invasive responses: a mechanism leading to increased malignancy in epithelial cells.

c-Raf-1 is a major effector of Ras proteins, responsible for activation of the ERK MAP kinase pathway and a critical regulator of both normal growth and oncogenic transformation. Using an inducible form of Raf in MDCK cells, we have shown that sustained activation of Raf alone is able to induce the transition from an epithelial to a mesenchymal phenotype. Raf promoted invasive growth in collagen gels, a characteristic of malignant cells; this was dependent on the operation of an autocrine loop involving TGFbeta, whose secretion was induced by Raf. TGFbeta induced growth inhibition and apoptosis in normal MDCK cells: Activation of Raf led to inhibition of the ability of TGFbeta to induce apoptosis but not growth retardation. ERK has been reported previously to inhibit TGFbeta signaling via phosphorylation of the linker region of Smads, which prevents their translocation to the nucleus. However, we found no evidence in this system that ERK can significantly influence the function of Smad2, Smad3, and Smad4 at the level of nuclear translocation, DNA binding, or transcriptional activation. Instead, strong activation of Raf caused a broad protection of these cells from various apoptotic stimuli, allowing them to respond to TGFbeta with increased invasiveness while avoiding cell death. The Raf-MAP kinase pathway thus synergizes with TGFbeta in promoting malignancy but does not directly impair TGFbeta-induced Smad signaling.

Animals↗
PubMed2000

Matrix detachment induces caspase-dependent cytochrome c release from mitochondria: inhibition by PKB/Akt but not Raf signalling.

Detachment of epithelial cells from extracellular matrix results in induction of apoptosis ('anoikis') which can be blocked by expression of activated Ras or PKB/Akt. Here we show that detachment causes release of cytochrome c from mitochondria in MDCK cells. This is blocked by caspase inhibitors, suggesting a role for caspases upstream of mitochondria in the initiation of anoikis, in accord with the ability of dominant negative FADD to inhibit this form of cell death. Bulk activation of caspase-8 following detachment lags behind cytochrome c release, and is likely the result of a mitochondrial positive feed back loop. Matrix detachment also induces Bax translocation to mitochondria in a caspase-dependent manner. Expression of activated Ras or PKB/Akt blocks all the detectable events on the detachment-induced apoptosis signalling pathway, suggesting that PKB/Akt acts at an early point in the pathway, providing the signal normally generated by matrix attachment. Strong activation of Raf can also protect MDCK cells from detachment induced apoptosis, but this occurs at a point downstream of cytochrome c release from mitochondria, and is clearly distinct from the effect of PKB/Akt. Oncogene (2000) 19, 4461 - 4468.

Animals↗
PubMed2000

Sendai virosomes revisited: reconstitution with exogenous lipids leads to potent vehicles for gene transfer.

A reliable new procedure is described for the reconstitution of Sendai viral envelopes suitable for gene transfer. Both fusion and hemagglutinin-neuraminidase glycoproteins were extracted from purified Sendai virus and reconstituted together with DNA in the presence of cholesterol:sphingomyelin:phosphatidylcholine:phosphatidylethanolamin e (Chol:SM:PC:PE) in a molar ratio of 3.5:3.5:2:1. Before reconstitution, the DNA to be transferred was condensed by pretreatment with polylysine. Exogenous lipid addition and the DNA-condensation step were essential for maximal size as well as for fusogenic activity of the resulting virosomes, the analysis of which revealed (1) the absence of any genomic material originating from Sendai virus, (2) the presence of fusogenic spikes in a functional orientation, (3) the encapsulation of reporter genes, and (4) high-transfer activity for plasmids carrying the green fluorescent protein (GFP) gene and double-stranded nucleotides into different mammalian cells. Transfer rates were up to 10-fold higher than those obtained with different cationic lipids. Gene delivery by means of our lipid-enriched Sendai virosomes extends the known gene transfer strategies, including those based on Sendai virus previously published.

Animals↗
PubMed2000

Axonal damage induced by invading T cells in organotypic central nervous system tissue in vitro: involvement of microglial cells.

Neuroinflammation in the course of multiple sclerosis and experimental autoimmune encephalomyelitis results in demyelination and, recently demonstrated, axonal loss. Invading neuroantigen specific T cells are the crucial cellular elements in these processes. Here we demonstrate that invasion of activated T cells induces a massive microglial attack on myelinated axons in entorhinal-hippocampal slice cultures. Flow cytometry analysis of activation markers revealed that the activation state of invading MBP-specific T cells was significantly lower in comparison to PMA-activated T cells. Moreover, MBP-specific T cells showed a significantly lower secretion of IFN-gamma. Conversely, MBP-specific T cells displayed a significantly higher potential to trigger activation of microglial cells, i.e. upregulation of MHC class II and ICAM-1 expression, and, most importantly, microglial phagocytosis of pre-traced axons. Our data suggest that this was mediated via specific cellular interactions of T cells and microglial cells since IFN-gamma alone was not sufficient to induce axonal damage while such damage was apparent in response to TNF-alpha which is released by activated microglial cells. TNF-alpha secretion by both T cell populations was negligible. Thus, MBP-specific T cells which invade nervous tissue in the course of neuroinflammation are more effective in axon-damaging recruiting microglial cells than activated T cells of other specificities.

Animals↗
PubMed2000

Lack of diagnostic tools to prove erectile dysfunction: consequences for reimbursement?

PURPOSE: Oral medications for treatment of erectile dysfunction may drastically increase health care expenses. Therefore, reimbursement for treatment will be limited in many countries. Proof of erectile dysfunction on an individual basis may be required. We determine whether erectile dysfunction can be proved by pharmacostimulation tests. MATERIALS AND METHODS: We prospectively evaluated 77 consecutive patients with a median age of 54 years (range 25 to 75) who presented with previously untreated erectile dysfunction. Assessment included patient reported semiquantitative data on sexual erections (rigidity, ability for vaginal intromission, duration), standard clinical and laboratory tests, and intracavernous injection test and color duplex sonography with 10 microg. intracavernous prostaglandin E1. Data were compared on the basis of the most important complaint, namely whether vaginal intromission was impossible, feasible only with manual assistance or possible but not long enough for satisfactory sexual performance. RESULTS: Of the 77 patients 36 (47%) were unable to perform vaginal intromission, 28 (37%) needed manual help and 13 (17%) had erections sufficient for penetration but were not satisfied with sexual performance. Patient reports were reliable as shown by the significant correlation of items (r = 0.77) and significant discriminating power among categories for penetration (analysis of variance p <0.001). In contrast, clinical response to intracavernous pharmacostimulation and flow parameters assessed by color duplex sonography could not discriminate among the groups. CONCLUSIONS: Erectile dysfunction could not be defined by pharmacostimulated erections but relevant erectile dysfunction was honestly reported. New and reliable tests for clinical assessment are required to support the application for reimbursement of treatment expenses for erectile dysfunction.

Adult↗
PubMed2000

Urinary level of nuclear matrix protein 22 in the diagnosis of bladder cancer: experience with 130 patients with biopsy confirmed tumor.

PURPOSE: We prospectively evaluated the value of nuclear matrix protein 22 (NMP22dagger) and cytology in the diagnosis of bladder cancer. MATERIALS AND METHODS: We analyzed NMP22 in voided urine from 235 patients before cystoscopy. Of the patients 130 had transitional cell carcinoma of the bladder and subsequently underwent surgery. In a subset of 200 patients bladder washout samples for cytology were collected during cystoscopy. The cutoff for NMP22 was 10.0 units per ml. For cytology only high grade atypia was considered positive. RESULTS: Histology showed 77 superficial (pTa, pTis) and 53 invasive (pT1 or greater) tumors. Sensitivity of NMP22 was 51% and specificity was 83%. NMP22 sensitivity was 36% for superficial tumors and 73% for invasive transitional cell carcinoma. Overall sensitivity of cytology was 52% and specificity was 89%. Cytology sensitivity was 38% for superficial tumors and 83% for invasive transitional cell carcinoma. NMP22 sensitivity for grades 1, 2 and 3 tumors was 30%, 56% and 68%, respectively. Cytology sensitivity for grades 1, 2 and 3 tumors was 30%, 50% and 91%, respectively. Combined NMP22 and cytology had a sensitivity of 70%. CONCLUSIONS: NMP22 has sensitivity and specificity similar to those of cytology from bladder washout samples. Particularly in low stage and low grade tumors both tests show the same disappointing sensitivity. Because of a false-negative rate of 49%, NMP22 cannot replace cystoscopy in clinical practice, as the danger of missing NMP22 negative tumors is too high to rely on its results in an individual patient.

Biomarkers, Tumor↗
PubMed1999

The Bcl-3 oncoprotein acts as a bridging factor between NF-kappaB/Rel and nuclear co-regulators.

The proto-oncoprotein Bcl-3 is a member of the IkappaB family and is present predominantly in the nucleus. To gain insight into specific nuclear functions of Bcl-3 we have isolated proteins that interact with its ankyrin repeat domain. Using the yeast two-hybrid-system we identified four novel binding partners of Bcl-3 in addition to NF-kappaB p50 and p52, previously known to associate with Bcl-3. The novel Bcl-3 interactors Jab1, Pirin, Tip60 and Bard1 are nuclear proteins which also bind to other transcription factors including c-Jun, nuclear factor I (NFI), HIV-1 Tat or the tumor suppressor and PolII holoenzyme component Brca1, respectively. Bcl-3, p50, and either Bard1, Tip60 or Pirin are sequestered into quarternary complexes on NF-kappaB DNA binding sites, whereas Jab1 enhances p50-Bcl-3-DNA complex formation. Furthermore, the histone acetylase Tip60 enhances Bcl-3-p50 activated transcription through an NF-kappaB binding site, indicating that quarternary complexes containing Bcl-3 interactors modulate NF-kappaB driven gene expression. These data implicate Bcl-3 as an adaptor between NF-kappaB p50/p52 and other transcription regulators and suggest that its gene activation function may at least in part be due to recruitment of the Tip60 histone actetylase.

Acetyltransferases↗
PubMed1999

[Sexually and drug-stimulated erections are proportional].

Even complex diagnostic tests may not establish aetiology and degree of erectile dysfunction (ED) in many patients. Therefore, we evaluated a self-report method with a restrictive focus to quality of erections which may yield information sufficient to make an aetiologic diagnosis. We studied 74 patients 25 to 75 years of age with untreated ED. Sexually stimulated erections were quantified and compared to duplexsonographically and clinically evaluated data from pharmacostimulated erections. Patients reported that there was a marked decrease in ability to penetrate the partner, to sustain an erection and of penile rigidity (p < 0.001). Parameters from duplexsonography and clinically assessed response to pharmacostimulation correlated (r = 0.72). Direct comparison of these data with quantified history showed no relation (r = 0.05). Using change in penile volume due to erection as a basis to compare with, showed significant correlation with quantified data from history (r = 0.26-0.34; p < 0.03) and measured parameters from pharmacostimulated erections (r = 0.44-0.55; p < 0.0001). Sexually- and pharmacostimulated erections are proportional to change in penile volume. Although there is a relation between erections emerging from both stimulations, quantifying history on sexually stimulated erections does not qualify to make an aetiologic diagnosis without using complex tests.

Adult↗
PubMed1999

Reasons for discontinuing intracavernous injection therapy with prostaglandin E1 (alprostadil).

OBJECTIVES: To clarify the reasons why experience with self-injection therapy for erectile dysfunction shows high dropout rates. METHODS: We studied 86 patients 36 to 76 years old who had been on home treatment for at least 3 months. Sixty-nine patients (80%) were continuing to use injections, and 17 (20%) had discontinued the treatment. Patients were evaluated by interview and clinical examination. RESULTS: Patients still in the program used one injection every 2 weeks, and those who had given up treatment had used one injection in 3 weeks (P = 0.31). They were in the program for 39+/-27 and 16+/-22 months (P = 0.002), respectively, and had used 50 (95% confidence interval [CI] 21 to 91) versus 12 (95% CI 4 to 20) injections, respectively (P<0.0001). Injections producing unsatisfactory penile rigidity, prolonged erections, hematoma at injection site, corporal fibrosis, secondary penile deviation, and mean estimated duration of a pharmacoinduced erection showed no significant differences. Patient satisfaction (P = 0.02), estimated partner satisfaction (P = 0.02), increase in self-esteem (P = 0.01), and negligible effort in performing injections (P = 0.001) all showed significantly better results for those still in the program. CONCLUSIONS: Reasons for dropout from self-injection therapy are not based on objective side effects and discomfort. Patients leaving the program are less motivated, less satisfied with the quality of pharmacoinduced sexuality, consider the effort to perform injections to be substantial, and have not achieved improved self-esteem.

Adult↗
PubMed1999

Variable response to intracavernous prostaglandin E1 testing for erectile dysfunction.

OBJECTIVES: Anxiety and apprehension may negatively influence the erectile response to the first intracavernous injection with vasoactive agents. This may result in too many false-positive diagnoses of vascular insufficiency if the first injection ever made in a patient is used for color Doppler duplex sonography (CDS) evaluation. METHODS: One hundred sixty-eight consecutive patients (aged 18 to 75 years) with erectile dysfunction underwent a standardized evaluation, including the intracavernous injection test (ICIT) stimulated with 10 microg prostaglandin E1. Responses were recorded on a four-point scale: no response = 0, tumescence = 1, rigidity sufficient for intercourse = 2, full erection = 3. ICIT was repeated after 10 days and combined with CDS. The clinically assessed response to ICIT was correlated with end-diastolic flow velocity. RESULTS: Of 168 patients, 114 (68%) responded equally to the first and second ICIT, but 45 (27%) had an improved response, from tumescence to full erection in the second test (P <0.0001); in 9 (5%), the response deteriorated. The overall mean response was 1.6 (95% confidence interval 1.5 to 1.7) and 1.9 (95% confidence interval 1.7 to 2.0) (P <0.0001) for the first and second test, respectively. Of 168 patients, 89 (53%) responded with erections sufficient for intercourse when tested the first time and 104 (62%) did so after the second injection. CONCLUSIONS: Erectile response to diagnostic intracavernous injection of prostaglandin E1 significantly improved in the second compared with the first test. Therefore, cautious interpretation of CDS is advised when patients are injected for the first time because too many false-positive tests may result.

Adolescent↗
PubMed1999

Clinical value of pelvic and penile magnetic resonance angiography in preoperative evaluation of penile revascularization.

Penile angiography is invasive, costly and requires postinterventional surveillance. The aim of this pilot study was to determine whether three dimensional magnetic resonance (3D-MR)-angiography may replace conventional penile angiography in preoperative planning of penile revascularization. Twelve patients with a mean age of 39 (21-59) y were evaluated. All patients underwent evaluation with intracavernous pharmacotesting, color Doppler sonography (CDS), digital subtraction angiography (DSA) and pelvic MR-angiography with gadolinium diethylene-triaminepentaacetic acid (Gd-Dota) 0.2-0.3 mmol/kg body weight. MR-angiography demonstrated the anatomy of the internal iliac arteries in 9 out of 12 patients. Intrapenile vessels were visible in 7 out of 12 patients. In comparison DSA provided complete visualization of all pelvic and penile vessels. Relevant arterial obstruction was found in 10 out of 12 patients. CDS revealed a mean maximal arterial flow of 27 (22-40) cm/s and showed in accordance to angiography arterial insuffiency in 10 out of 12 cases. Indication for revascularization could have been based on MR-angiography alone in only one patient. Therefore, selective penile angiography remains the 'gold standard' for preoperative planning of revascularization procedures.

Adult↗
PubMed1999

Treatment for human immunodeficiency virus with indinavir may cause relevant urological side-effects, effectively treatable by rehydration.

OBJECTIVE: To explore the occurrence of, and diagnostic and therapeutic procedures for urological side-effects (e.g. micro- and macrohaematuria, and kidney stone formation) in individuals treated with indinavir for the human immunodeficiency virus (HIV). PATIENTS AND METHODS: The study comprised a retrospective follow-up of 74 individuals infected with HIV-1 and who were treated with indinavir orally at a daily dose of 2.4 g. Data were collected at the outpatient department of our institution between March 1996 and November 1997. RESULTS: Of the 74 individuals treated with indinavir, 15 (20%) had indinavir-related urological side-effects (19 episodes), most commonly dull flank pain and dysuria. Microhaematuria occurred in 16 of the 19 episodes. Four patients showed urinary tract distension ultrasonographically as a possible indirect sign of urolithiasis and one patient passed a kidney stone. In four patients treatment had to be stopped permanently, but in the remaining 11 patients treatment was continued. Some patients required dose reduction and/or interruption of treatment; only conservative therapeutic measures were required, consisting of rehydration (fluid intake >1.5 L/day) and analgesics. CONCLUSIONS: Urological side-effects of indinavir may be apparent in 20% of patients so treated; some (5%) may require permanent withdrawal. In addition to a history and clinical examination, urine analysis and ultrasonography were the only diagnostic procedures required. Therapy is mainly conservative, using rehydration, analgesics and a brief discontinuation of therapy, according to the severity of the symptoms.

Acquired Immunodeficiency Syndrome↗