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Biomedical subjects

Peter Klein

Publications and source records attributed to Peter Klein.

At least 19 recordsLinked to original sources
PubMed2006

Surgical management of pulmonary metastases from colorectal cancer in 153 patients.

BACKGROUND: Surgery has become a recognized therapeutic means in selected patients with pulmonary metastases from colorectal origin. We reviewed our experience in the surgical treatment of 153 patients with pulmonary colorectal metastases and investigated factors affecting survival. METHODS: A retrospective analysis of the records of all patients (n = 153) with pulmonary metastases from colorectal cancer who underwent thoracotomy between 1978 and 2003 at a single surgical center was performed. RESULTS: One hundred fifty-three patients with pulmonary metastases from colon (n = 61) or rectal (n = 92) cancer underwent 180 thoracotomies. The 2- and 5-year probabilities of survival after the first thoracotomy were 64% and 37%, respectively. Sex, age, site, International Union Against Cancer stage of the primary tumor, prethoracotomy carcinoembryonic antigen level, size of metastases, and previous resection of hepatic metastases were not found to be statistically significant prognostic factors. Number of metastases (solitary vs. multiple), mode of operation (wedge vs. anatomical resection), disease-free interval (DFI; > 36 months), negative hilar or mediastinal lymph node status, resection margin > 10 mm, and administration of intraoperative blood substitution were predictors of a longer survival duration by univariate analysis, but only number of metastases (P = .019), mode of operation (P = .004), DFI (P = .027), and intraoperative blood substitution (P = .002) were identified as independent prognostic factors by multivariate analysis. CONCLUSIONS: Pulmonary resection for metastases from colorectal cancer is safe and results in long-term survival in selected patients. Single metastases, anatomical resection, intraoperative blood substitution, and DFI > 36 months seem to be the most reliable predictors of survival.

Adult↗
PubMed2006

On the nature of low- and high-affinity EGF receptors on living cells.

The small subpopulation of high-affinity EGF receptors (EGFRs) on living cells revealed by Scatchard analysis of (125)I-EGF binding results was discovered nearly three decades ago, yet not much is known about the underlying mechanism. After the determination of the structure of different forms of EGFR extracellular domain it was proposed that the monomeric tethered configuration corresponds to the majority of low-affinity receptors, whereas the extended dimeric configuration corresponds to the minority of the high-affinity class of EGFRs. Mathematical modeling of EGF-binding experiments to different conformational mutants of EGFR has shown that the high-affinity class of EGFR on living cells does not correspond to the extended configuration of EGFR and can only be accounted for by including in the mathematical model an additional binding event that is attributed to the dynamic nature of EGFR on living cells. To circumvent this problem we have performed similar experiments in the background of an EGFR mutant that does not form high-affinity sites. Quantitative analysis and mathematical modeling of these data show that release of the intramolecular tether causes a 2-fold increase in EGF-binding affinity, whereas elimination of the dimerization arm reduces EGF-binding affinity by approximately 6-fold. These experiments confirm the salient features of the structural model for EGFR regulation and argue further that the intramolecular tether provides only limited autoinhibitory control of EGFR activity and that the low-affinity class of EGF-binding sites on living cells reflects interconverting, tethered, and extended receptor configurations.

Binding Sites↗
PubMed2006

Echinacea in the prevention of induced rhinovirus colds: a meta-analysis.

BACKGROUND: The therapeutic effectiveness of Echinacea in the treatment and the prevention of colds has been debated. Studies of naturally occurring colds are hampered by variability in time from onset of symptoms to treatment and by heterogeneity in trial design. Experimental infection studies allow for the standardization of time to initiation of treatment, virus type and dose, and immune competence of volunteers. OBJECTIVE: To determine whether the negative results obtained in previous studies of Echinacea were a consequence of efficacy or of inadequate sample size, we performed a meta-analysis of experimental rhinovirus infection studies on the efficacy of Echinacea extracts to prevent symptomatic development of an experimentally induced cold. METHODS: We carried out a systematic search of English- and German-language literature using the MEDLINE, EMBASE, CAplus, BIOSIS, CABA, AGRICOLA, TOXCENTER, SCISEARCH, NAHL, and NAPRALERT, databases and the search terms Echinacea, black Sampson, coneflower, and Roter Sonnenbut. Matching documents were then searched for > or = 1 of the following terms: rhinovirus, RV, inoculation, Inokulation, induced, induziert, artificial, and artifiziell. Suitable studies were identified and pooled for analysis. The primary end point was the development of symptomatic clinical colds, as defined by the authors of the original studies. Results were reported as differences in the proportion of subjects with symptomatic episodes of a common cold, expressed as odds ratios (ORs) and 95% CIs. The secondary outcome was the difference in total symptom severity scores between treatment groups (assessed daily by integrating the severity scores of 8 individual cold-related symptoms that were rated on a scale from 0 [absent] to 4 [very severe]). RESULTS: A total of 234 articles were identified through the literature search; 231 were excluded from the analysis because they related to studies of spontaneous common colds. Three suitable studies were selected for pooling of data. Based on the analysis, the likelihood of experiencing a clinical cold was 55% higher with placebo than with Echinacea (OR, 1.55 [95% CI, 1.02-2.36]; P<0.043). The absolute difference in total symptom scores between groups was -1.96 (95% CI, -4.83 to 0.90; P=NS). CONCLUSIONS: This meta-analysis suggests that standardized extracts of Echinacea were effective in the prevention of symptoms of the common cold after clinical inoculation, compared with placebo. Further prospective, appropriately powered clinical studies are required to confirm this finding.

Common Cold↗
PubMed2006

A complex homeopathic preparation for the symptomatic treatment of upper respiratory infections associated with the common cold: An observational study.

BACKGROUND: The use of complementary medicines is large and growing in both the United States and Europe. OBJECTIVE: To compare the effects of a complex homeopathic preparation (Engystol; Heel GmbH, Baden-Baden, Germany) with those of conventional therapies with antihistamines, antitussives, and nonsteroidal antiinflammatory drugs on upper respiratory symptoms of the common cold in a setting closely related to everyday clinical practice. DESIGN: Nonrandomized, observational study over a treatment period of maximally two weeks. SETTING: Eighty-five general and homeopathic practices in Germany. PARTICIPANTS: Three hundred ninety-seven patients with upper respiratory symptoms of the common cold. INTERVENTIONS: Engystol-based therapy or common over-the-counter treatments for the common cold. Patients receiving this homeopathic treatment were allowed other short-term medications, but long-term use of analgesics, antibiotics, and antiinflammatory agents was not permitted. Patients were allowed nonpharmacological therapies such as vitamins, thermotherapies, and others. MAIN OUTCOME MEASURES: The effects of treatment were evaluated on the variables fatigue, sensation of illness, chill/tremor, aching joints, overall severity of illness, sum of all clinical variables, temperature, and time to symptomatic improvement. RESULTS: Both treatment regimens provided significant symptomatic relief, and this homeopathic treatment was noninferior in a noninferiority analysis. Significantly more patients (P < .05) using Engystol-based therapy reported improvement within 3 days (77.1% vs 61.7% for the control group). No adverse events were reported in any of the treatment groups. CONCLUSION: This homeopathic treatment may be a useful component of an integrated symptomatic therapy for the common cold in patients and practitioners choosing an integrative approach to medical care.

Adult↗
PubMed2006

Kinetics of human serum butyrylcholinesterase and its inhibition by a novel experimental Alzheimer therapeutic, bisnorcymserine.

An explosion in the incidence of neurodegenerative diseases, particularly Alzheimer's disease (AD), is predicted in coming decades. Hence, the need to devise and assess new treatment strategies has never been more acute. AD, although an irreversible and progressive disorder, is currently treated with palliative, symptomatic therapy: primarily with acetylcholinesterase (AChE) inhibitors to amplify remaining cholinergic activity. New agents that, additionally, affect disease progression are sorely needed. Inhibition of brain butyrylcholinesterase (BuChE) represents a new drug target for AD treatment. Therefore, hand-in-hand with the development of selective ligands to inhibit BuChE in brain, it is fundamental to optimize assay conditions for kinetic studies of human BuChE. Kinetic analysis of serum BuChE, which is structurally similar to brain enzyme, was performed at dual substrate (butyrylthiocholine iodide) concentration ranges: 3-80 microM (low) and 25-800 microM (optimal) by use of the Ellman technique. Interaction of BuChE with a novel experimental AD therapeutic, bisnorcymserine (BNC; 0.06-2.0 nM) was also studied ex vivo. The IC_{50} and other key kinetic constants were determined for human serum BuChE inhibition by BNC, which proved to be a highly potent inhibitor in comparison to its structural analogue, cymserine. BNC may, additionally, lower the amyloid plaque-associated protein, amyloid-beta peptide. In synopsis, the characterization of the kinetic parameters of BuChE and BNC, described herein, is both aiding in the design of novel agents and optimizing their translation toward clinical use.

Alzheimer Disease↗
PubMed2005

New 2-bromomethyl-8-substituted-benzo[c]chromen-6-ones. Synthesis and biological properties.

New 2-bromomethyl-8-substituted-benzo[c]chromen-6-ones have been synthesized and their bioactive properties have been evaluated on different enzymatic models: serine proteases (trypsin and alpha-chymotrypsin), HIV aspartyl protease, nitric oxide synthase and a panel of protein kinases. These new derivatives can provide upon chemical or enzymatic attack, very reactive quinonimine methide intermediates, which could be utilized for the design of enzyme inhibitors. We found that some of these new derivatives exhibit modest inhibitory activities on the studied enzyme models, but it could be improved after structure optimization.

Aspartic Acid Endopeptidases↗
PubMed2005

Flow-cytometric analysis of peripheral blood neutrophils: a simple, objective, independent and potentially clinically useful assay to facilitate the diagnosis of myelodysplastic syndromes.

The diagnosis of myelodysplastic syndromes (MDS) is based upon cytopenias, morphologic dysplasia, and cytogenetic abnormalities. Because morphologic dyspoiesis may be subtle, and many cases have normal cytogenetics, additional objective diagnostic tools are needed. We previously developed a novel peripheral blood neutrophil flow-cytometric (FCM) scoring system to identify patients with MDS. Here, in an analysis of 25 patients, we demonstrate that FCM abnormalities are independent of currently measured parameters in MDS, including cytopenias, marrow blast percent, and IPSS score. Importantly, FCM abnormalities were seen in 9/16 MDS patients with normal cytogenetics, suggesting that this simple, non-invasive assay could play a central role in the diagnosis of MDS.

Adult↗
PubMed2005

Peripheral blood MDS score: a new flow cytometric tool for the diagnosis of myelodysplastic syndromes.

BACKGROUND: Myelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic disorders diagnosed using morphologic and clinical findings supported by cytogenetics. Because abnormalities may be subtle, diagnosis using these approaches can be challenging. Flow cytometric (FCM) approaches have been described; however the value of bone marrow immunophenotyping in MDS remains unclear due to the variability in detected abnormalities. We sought to refine the FCM approach by using peripheral blood (PB) to create a clinically useful tool for the diagnosis of MDS. METHODS: PB from 15 patients with MDS was analyzed by multiparametric flow cytometry using an extensive panel of monoclonal antibodies. Patterns of neutrophil antigen expression were compared with those of normal controls (n = 16) to establish light scatter and/or immunophenotypic abnormalities that correlated with MDS. A scoring algorithm was developed and validated prospectively on a blinded patient set. RESULTS: PB neutrophils from patients with MDS had lower side scatter and higher expression of CD66 and CD11a than did controls. Some MDS PB neutrophils demonstrated abnormal CD116 and CD10 expression. Because none of these abnormalities proved consistently diagnostic, we sought to increase the power of the assay by devising a scoring system to allow the association of multiple abnormalities and account for phenotypic variations. The PB MDS score differentiated patients with MDS from controls (P < 0.0001) in the test set. In a prospective validation, the PB MDS score successfully identified patients with MDS (sensitivity 73%, specificity 90%). CONCLUSIONS: FCM analysis of side scatter and only four additional immunophenotypic parameters of PB neutrophils using the PB MDS score proved more sensitive than standard laboratory approaches and may provide an additional, more reliable diagnostic tool in the identification of MDS.

Aged↗
PubMed2005

The effects of a complex homeopathic medicine compared with acetaminophen in the symptomatic treatment of acute febrile infections in children: an observational study.

CONTEXT: Children frequently suffer infections accompanied by fever, which is commonly treated with acetaminophen (paracetamol), a use not devoid of risk. OBJECTIVE: The effect of a complex homeopathic medicine (Viburcol, Heel Belgium, Gent, Belgium) was compared with that of acetaminophen in children with infectious fever. DESIGN: Non-randomized observational study. SETTING: Thirty-eight Belgian centers practicing homeopathy and conventional medicine. PATIENTS: Children <12 years old. INTERVENTIONS: Viburcol (drops) or acetaminophen (pills, capsules, or liquid form) for a maximum of 2 weeks. MAIN OUTCOME MEASURES: Fever, cramps, distress, disturbed sleep, crying, and difficulties with eating or drinking. Symptoms were graded by the practitioner on a scale from 0 to 3. Severity of infection was evaluated on a scale from 0 to 4. Data were captured on body temperature, subjective impression of health status, time to first improvement of symptoms, and global evaluation of treatment effects. Tolerability and compliance were monitored. RESULTS: Both treatment groups improved during the treatment period. Body temperature was reduced by 1.7 degrees C +/- 0.7 degrees C with Viburcol and by 1.9 degrees C +/- 0.9 degrees C with acetaminophen; fever score (scale from 0 to 3) from 1.7 +/- 0.6 to 0.1 +/- 0.2 with Viburcol and from 1.9 +/- 0.7 to 0.2 +/- 0.5 with acetaminophen (all values mean +/-SD). The overall severity of infection (scale from 0 to 4) decreased from 2.0 +/- 0.5 to 0.0 +/- 0.2 with Viburcol and from 2.2 +/- 0.7 to 0.2 +/- 0.6 with acetaminophen. There were no statistically significant differences between treatment groups in time to symptomatic improvement. Viburcol was noninferior to acetaminophen on all variables evaluated. Both treatments were very well tolerated, but the Viburcol group had a significantly greater number of patients with the highest tolerability score. CONCLUSIONS: In this patient population, Viburcol was an effective alternative to acetaminophen treatment and significantly better tolerated.

Acetaminophen↗
PubMed2005

A homeopathic ointment preparation compared with 1% diclofenac gel for acute symptomatic treatment of tendinopathy.

CONTEXT: The incidence of tendon injuries and tendinopathy has risen substantially in the past decades. OBJECTIVE: To assess the noninferiority of therapy based on the homeopathic preparation Traumeel S ointment (Heel GmbH, Baden-Baden, Germany) compared with treatment based on diclofenac 1% gel in patients with tendinopathies of varying etiology. DESIGN: Nonrandomized, observational study. SETTING: Ninety-five homeopathy and conventional medical practices in Germany. PATIENTS: Three hundred fifty-seven patients aged 18 to 93 years with tendinopathy of varying etiology based on excessive tendon load rather than inflammation. INTERVENTIONS: Traumeel S ointment or diclofenac 1% gel for a maximum of 28 days. MAIN OUTCOME MEASURES: Efficacy was measured on a four-degree scale on pain-related variables, on variables related to motility, and on overall treatment outcome. Tolerability was monitored as adverse events. Compliance was assessed by practitioner and patient on a four-degree scale. RESULTS: The patients groups were comparable at baseline. The changes in summary score of all pain-related variables were -5.3 +/- 2.7 (all values means +/- SD) in the Traumeel group and -5.0 +/- 2.7 in the control group. Changes for all motility-related variables were -4.2 +/- 3.8 with Traumeel and -3.7 +/- 3.4 with control therapy. The summary scores for all clinical variables were reduced by -9.5 +/- 5.7 with Traumeel therapy and by -8.7 +/- 5.4 with diclofenac-based treatment. Homeopathic therapy was noninferior to diclofenac therapy on all variables. For motility-related variables, there was a trend toward superiority of Traumeel. Treatments were well tolerated with no treatment-related adverse events. CONCLUSIONS: The results suggest that Traumeel ointment is an effective alternative to nonsteroidal antiinflammatory drugs therapy for the acute symptomatic treatment of patients with tendinopathy.

Adult↗
PubMed2005

Treatment of vertigo with a homeopathic complex remedy compared with usual treatments: a meta-analysis of clinical trials.

The increasing interest in alternative medical practices has led to a number of controlled studies on herbal and homeopathic agents. This paper presents the results of a meta-analysis of four recent clinical trials evaluating the homeopathic preparation Vertigoheel (VH) compared with usual therapies (betahistine, Ginkgo biloba extract, dimenhydrinate) for vertigo in a total of 1388 patients. Two trials were observational studies and the other two were randomised double-blind controlled trials. The duration of treatment (6-8 weeks) and dosage were comparable in all studies. Treatments were evaluated for the variables "number of vertigo episodes", "intensity of episodes" and "duration of episodes". As the studies differed in the age of patients and in the baseline values of vertigo, the individual reductions of number, intensity and duration of episodes were adjusted on equal age and baseline values (total means). An analysis of variance (with studies as random effects) showed no relevant influence of studies on the adjusted reductions and no relevant interaction between studies and treatment effects. The meta-analysis of all four trials showed equivalent reductions with VH and with control treatment: mean reduction of the number of daily episodes 4.0 for VH and 3.9 for control (standard error 0.11 for both groups); mean reduction of the duration (on a scale 0-4) for VH 1.1 and for the control 1.0 (standard error 0.03 for both groups); mean reduction of the intensity (on a scale 0-4) for VH 1.18 and for the control 1.8 (standard error 0.03 for both groups). In the non-inferiority analysis from all trials, VH was non-inferior in all variables. The results show the applicability of meta-analyses on the data from studies with homeopathicdrugs and support the results from the individual studies indicating good efficacy and tolerability of VH in patients with vertigo.

Betahistine↗
PubMed2005

The homeopathic preparation Vertigoheel versus Ginkgo biloba in the treatment of vertigo in an elderly population: a double-blinded, randomized, controlled clinical trial.

OBJECTIVE: Alternative medical practices are common in the treatment of vertigo. This study compared the effects of Ginkgo biloba treatment with the homeopathic remedy Vertigoheel (Biologische Heilmittel Heel GmbH, Baden-Baden, Germany). DESIGN: Randomized, double-blinded, parallel group study. SUBJECTS: One hundred and seventy (170) patients, ages 60-80 years, with atherosclerosis-related vertigo. INTERVENTIONS: Patients were randomly allocated to receive treatment with either Vertigoheel (n = 87) or G. biloba (n = 83). OUTCOME MEASURES: The results were analyzed for the non-inferiority of Vertigoheel to G. biloba on the combined endpoint of changes from baseline to week 6 in dizziness score (assessed by questionnaire), frequency, duration, and intensity of vertigo episodes (recorded in patient diaries). RESULTS: Both treatments improved vertigo status. From a baseline mean value of 26.1 +/- 5.2 (on a 50-point scale) in the Vertigoheel group, the dizziness questionnaire score improved by -10.6 +/- 10.0, and by -10.7 +/- 9.0 from 25.8 - 4.7 in the G. biloba group. Statistical analysis of this endpoint showed that Vertigoheel was not inferior to G. biloba. The 95% confidence interval for the difference between treatment did not reach the inferiority threshold of 0.36 at any of the time points tested. The results were supported by the results of a line walking test, Unterberger's stepping test, and patient and physician global assessments of therapeutic effect. Both treatments were well tolerated. CONCLUSIONS: Vertigoheel is an appealing alternative to established G. biloba therapy for atherosclerosis-related vertigo.

Aged↗
PubMed2005

[Treatment of inflammatory diseases of the upper respiratory tract -- comparison of a homeopathic complex remedy with xylometazoline].

INTRODUCTION: The primary objective of treatment of inflammatory diseases of the upper respiratory tract (rhinitis, uncomplicated sinusitis) with local decongestants is to relieve obstruction and to improve associated symptoms. Restoration of unrestricted respiration and drainage of the nasal sinuses reduce the risk of further complications (i.e. chronicity). OBJECTIVE: To determine whether the therapeutic effects of the homeopathic complex remedy Euphorbium compositum nasal drops SN are comparable to those of xylometazoline with respect to efficacy and tolerability. METHODS: Open, multicenter, prospective, active-controlled cohort study in patients with inflammatory processes and diseases of the upper respiratory tract. The primary outcome was to demonstrate non-inferiority of the homeopathic complex remedy to xylometazoline. RESULTS: Clinically relevant reductions in the intensities of disease-specific symptoms were observed with both therapies. Non-inferiority of the homeopathic complex remedy to xylometazoline could be shown for all studied variables and in no case did the lower boundary of the 95% confidence interval cross the threshold of 0.5 score points. Tolerability was good with for both therapies. CONCLUSIONS: This cohort study indicates a comparable efficacy and tolerability profile of the homeopathic complex remedy Euphorbium compositum nasal drops SN and the reference substance xylometazoline in patients with inflammatory processes and diseases of the upper respiratory tract.

Adult↗
PubMed2004

Cdx1 inhibits human colon cancer cell proliferation by reducing beta-catenin/T-cell factor transcriptional activity.

The cessation of proliferation and the induction of differentiation are highly coordinated processes that occur continuously in the intestinal crypts. The homeodomain transcription factors Cdx1 and Cdx2 regulate intestine-specific gene expression and enterocyte differentiation. Their roles in regulating proliferation are recognized but remain poorly understood. Previously, we demonstrated that Cdx1 expression diminished the proliferation of human colon cancer cells in part by reducing cyclin D1 gene expression. In order to elucidate further the molecular mechanisms underlying this phenomenon, we first hypothesized that Cdx1 or Cdx2 expression reduces colon cancer cell proliferation by inhibiting beta-catenin/T-cell factor (TCF) transcriptional activity. We report that Cdx1 or Cdx2 expression does inhibit beta-catenin/TCF transcriptional activity in colon cancer cells. This inhibitory effect is dose-dependent and is observed in different colon cancer cell lines, and the degree of inhibition correlates with the ability of Cdx1 to reduce cell proliferation. Cdx1 expression does not alter beta-catenin protein levels or intracellular distribution nor does it induce an inhibitory TCF isoform. We also find that Cdx1 expression is lost in Min mouse polyps with increased nuclear localization of beta-catenin, suggesting that Cdx1 does not support beta-catenin-mediated transformation. Finally, we show that colon cancer cells effectively reduce Cdx2-mediated inhibition of Wnt/beta-catenin/TCF transcriptional activity when compared with other model systems. This suggests that colon cancer and possibly crypt epithelial cells can modulate the effects of Cdx2 on beta-catenin signaling and proliferation. We conclude that Cdx1 and Cdx2 inhibit colon cancer cell proliferation by blocking beta-catenin/TCF transcriptional activity.

Adenoviridae↗
PubMed2004

A structure-based model for ligand binding and dimerization of EGF receptors.

On the basis of the 3D structures of the extracellular ligand-binding domains of the epidermal growth factor (EGF) receptor (EGFR) and ErbB3, a mechanism has been proposed for how the extracellular region of the EGFR is maintained in an autoinhibited configuration and for how EGF binding induces EGFR dimerization and activation. We have attempted to derive a mathematical model for EGF binding to the EGFR and for ligand-induced receptor dimerization and activation that uses this structural information and can explain the characteristic concave-up curvilinear Scatchard plots seen when EGF binding to intact EGFR is studied in living cells. We show that these curvilinear plots cannot be accounted for by simply ascribing different affinities to the autoinhibited and extended (dimeric) configurations of the receptor seen in structural studies. Concave-up plots can only be obtained by including in the mathematical model an additional binding event in which occupied EGFR dimers bind to an "external site." The external site may represent receptor interactions with coated-pit regions in the cell membrane or with other cellular components involved in receptor endocytosis and turnover. We conclude in this study and in the accompanying article that the active extended EGFR configuration binds EGF 5- to 20-fold more strongly than the autoinhibited monomeric receptor configuration. However, these extended receptors do not correspond directly with the "high-affinity" EGF-binding sites seen in EGF-binding studies on intact cells.

Dimerization↗