Biomedical subjects

Martin Hoffmann

Publications and source records attributed to Martin Hoffmann.

12 recordsLinked to original sources

PubMed2006

Differences in nephrotoxicity of intravenous bisphosphonates for the treatment of malignancy-related bone disease.

Renal dysfunction is a particularly problematic adverse event that requires additional management and can prohibit the use of certain medications. Due to their renal uptake and elimination, some bisphosphonates can cause nephrotoxicity when used for the treatment of skeletal-related events in patients with bone metastases. However, clinical studies and post-marketing experience indicate that renal effects do not appear to be the same for all bisphosphonates. Zoledronic acid and pamidronate appear to be associated with a greater risk of renal toxicity, especially when given in high doses or over short infusion times. In contrast, high loading doses of intravenous ibandronate (3 x 6 mg given on days 1-3) have shown no additional renal safety concerns, and intravenous ibandronate 6 mg appears to have a renal safety profile comparable to placebo. This paper reviews the renal safety of intravenously administered bisphosphonates and makes some suggestions, based on preclinical and clinical data, as to why renal safety profiles may differ.

Bone Density Conservation Agents↗

PubMed2006

Collapse of spherical polyelectrolyte brushes in the presence of multivalent counterions.

We consider the interaction of multivalent counterions with spherical polyelectrolyte brushes (SPB). The SPB result if linear polyelectrolyte (PE) chains (contour length: 60 nm) are densely grafted to colloidal spheres of 116 nm in diameter. Dispersed in water, the surface layer consisting of chains of the strong PE poly(styrene sulfonic acid) (PSS) will swell. We demonstrate that successive addition of trivalent ions (La3+) leads to a collapse in which the surface layer is shrinking drastically. All findings are discussed on the base of a theoretical mean-field approach using the Donnan equilibrium. The ion exchange and a strong binding of trivalent ions by PE chains is followed up by a drop in the osmotic pressure inside the brush. This reduction is the driving force for the collapse. The strong ion-chain correlation is discussed with results obtained from molecular dynamics simulations.

Cations↗

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

Robust computational reconstitution - a new method for the comparative analysis of gene expression in tissues and isolated cell fractions.

BACKGROUND: Biological tissues consist of various cell types that differentially contribute to physiological and pathophysiological processes. Determining and analyzing cell type-specific gene expression under diverse conditions is therefore a central aim of biomedical research. The present study compares gene expression profiles in whole tissues and isolated cell fractions purified from these tissues in patients with rheumatoid arthritis and osteoarthritis. RESULTS: The expression profiles of the whole tissues were compared to computationally reconstituted expression profiles that combine the expression profiles of the isolated cell fractions (macrophages, fibroblasts, and non-adherent cells) according to their relative mRNA proportions in the tissue. The mRNA proportions were determined by trimmed robust regression using only the most robustly-expressed genes (1/3 to 1/2 of all measured genes), i.e. those showing the most similar expression in tissue and isolated cell fractions. The relative mRNA proportions were determined using several different chip evaluation methods, among which the MAS 5.0 signal algorithm appeared to be most robust. The computed mRNA proportions agreed well with the cell proportions determined by immunohistochemistry except for a minor number of outliers. Genes that were either regulated (i.e. differentially-expressed in tissue and isolated cell fractions) or robustly-expressed in all patients were identified using different test statistics. CONCLUSION: Robust Computational Reconstitution uses an intermediate number of robustly-expressed genes to estimate the relative mRNA proportions. This avoids both the exclusive dependence on the robust expression of individual, highly cell type-specific marker genes and the bias towards an equal distribution upon inclusion of all genes for computation.

Arthritis, Rheumatoid↗

PubMed2006

Proteinuria in diabetic patients--is it always diabetic nephropathy?

BACKGROUND: Diabetic nephropathy (dNP) is a consequence of type 1 and type 2 diabetes, typically occurring between 5 and 15 years after diabetes has been diagnosed. The coincidence of dNP and diabetic retinopathy (dRP) is well known. In this study we correlated the histological findings of the kidney biopsy with the clinically expected diagnosis of dNP. PATIENTS AND METHODS: Over a 4-year period with a total of 326 kidney biopsies, 85 biopsies were performed on patients with diabetes. In all of these patients we had information about duration of diabetes and ophthalmological status. Additionally, data about proteinuria, urine sediment and autoantibodies were available. The nephrologist had to give the suspected diagnosis before the biopsy was performed, using the clinical data available. RESULTS: In 57 patients (67%) dNP was predicted clinically before biopsy. In 28 patients we expected a different kind of kidney disease. Only 43 patients had dNP histologically. In 16 out of 19 patients with dRP we also found dNP. 26 patients with dNP did not have dRP. So dRP was very specific but not sensitive to predict dNP. On the other hand, all patients without dRP but acanthocytes in urine sediment had non-diabetic kidney disease (NDKD). In the case of patients with neither dRP nor acanthocytes, it was very difficult to distinguish between dNP and NDKD. Acanthocytes and antineutrophil cytoplasmatic antibodies with positive antibodies for proteinase 3 or myeloperoxidase were found only in NDKD, but ANAs were detected in a wide titer range in dNP and NDKD. The known duration of the diabetes ranged from 1 to 40 years. There were no additional parameters to differentiate this group. CONCLUSIONS: Diabetic patients with dRP and proteinuria frequently have dNP. In patients without typical retinal findings dNP is less likely, thus a kidney biopsy is necessary to confirm the diagnosis. Additional knowledge about urine sediment and autoantibodies is helpful, but is not sufficient to differentiate NDKD from dNP in the majority of patients.

Aged↗

PubMed2006

Ibandronate for the treatment of hypercalcemia or nephrocalcinosis in patients with multiple myeloma and acute renal failure: Case reports.

Multiple myeloma disrupts calcium homeostasis by a variety of mechanisms, including bone destruction and resorption. This causes hypercalcemia. When left untreated, hypercalcemia leads to nephrocalcinosis, impairment of kidney function, and eventually renal failure. Some degree of renal dysfunction is common in myeloma patients. Here, we report case studies showing the efficacy and renal safety of the single-nitrogen bisphosphonate, ibandronate, for the treatment of hypercalcemia and/or nephrocalcinosis in multiple myeloma patients hospitalized with acute renal failure. Patients (n = 7) received either one or two intravenous infusions of ibandronate (2-6 mg). Ibandronate was well tolerated in all patients and returned elevated blood calcium levels to normal. Renal function improved for all patients and normalized in 3/7 patients. We conclude that ibandronate is involved in rapidly improving or restoring acute renal function and calcium levels to within the normal range in this patient population. To clarify the exact value of ibandronate, further investigation is warranted in randomized prospective trials.

Acute Kidney Injury↗

PubMed2005

Fluconazole dosing in continuous veno-venous haemofiltration (CVVHF): need for a high daily dose of 800 mg.

To cover intermediate sensitive Candida glabrata in ICU patients, fluconazole plasma peak levels at least in the range of 16-32 microg/ml appear necessary for treatment. Previous studies did not reach these fluconazole levels under continuous veno-venous haemofiltration (CVVHF) with dosages of 200-600 mg fluconzole daily. In the present study, nine patients simultaneously requiring CVVHF for treatment of acute oligoanuric renal failure and antimycotic therapy of Candida septicemia received fluconazole 800 mg/day. Fluconazole plasma levels were determined to evaluate whether this dosage is adequate to reach the advised fluconazole levels. Patients were dialysed on two consecutive days with an ultrafiltration rate (UF) of 1000 ml/h or 2000 ml/h, respectively, in a randomized order. The predilution was 800 ml/h and 1800 ml/h, respectively. The treatment was tolerated without adverse effects. All patients reached plasma fluconazole concentrations between 16 and 32 microg/ml, remaining in this range for a minimum of 1 up to 24 h with a mean of 9.6 h and a UF rate of 2000 ml/h, and 15.7 h with a UF rate of 1000 ml/h. So far, there are no in vivo data on the fluconazole plasma concentrations required for effective treatment. However, our data demonstrate, that at least the fluconazole concentrations desirable on the basis of in vitro susceptibility testing can be reached in critically ill patients on CVVHF in an ICU setting. However, in these patients, 800 mg fluconazole/day are necessary to achieve fungicidal drug concentrations.

Acute Kidney Injury↗

PubMed2004

Dynamic network reconstruction from gene expression data applied to immune response during bacterial infection.

MOTIVATION: The immune response to bacterial infection represents a complex network of dynamic gene and protein interactions. We present an optimized reverse engineering strategy aimed at a reconstruction of this kind of interaction networks. The proposed approach is based on both microarray data and available biological knowledge. RESULTS: The main kinetics of the immune response were identified by fuzzy clustering of gene expression profiles (time series). The number of clusters was optimized using various evaluation criteria. For each cluster a representative gene with a high fuzzy-membership was chosen in accordance with available physiological knowledge. Then hypothetical network structures were identified by seeking systems of ordinary differential equations, whose simulated kinetics could fit the gene expression profiles of the cluster-representative genes. For the construction of hypothetical network structures singular value decomposition (SVD) based methods and a newly introduced heuristic Network Generation Method here were compared. It turned out that the proposed novel method could find sparser networks and gave better fits to the experimental data. CONTACT: Reinhard.Guthke@hki-jena.de.

Algorithms↗

PubMed2004

Phase I/II clinical study of topotecan and cytarabine in patients with myelodysplastic syndrome, chronic myelomonocytic leukemia and acute myeloid leukemia.

Topotecan, a topoisomerase-I inhibitor is an active drug in the treatment of AML and MDS. To evaluate its toxicity and efficacy in a combination regimen with cytarabine, we conducted a clinical phase I/II trial in patients with relapsed acute myeloid leukemia (AML) or relapsed or newly diagnosed MDS RAEB, RAEB-t or CMML. Twenty-one patients (11 AML, 10 MDS/CMML) entered the study and were treated with 1.25 mg/m2 topotecan as continuous intravenous infusion daily for 5 days and cytarabine 1.0 g/m2 by infusion over 2 h daily for 5 days (TA). Cycles were repeated on day 28. The median observation time was 131 weeks (range: 36-196 weeks). A total of 37 cycles of TA were administered. In 1 patient, the dose of TA had to be reduced and in 1 patient, there was a treatment delay for the second cycle, both because of hematologic toxicity. The most frequent non-hematologic side-effect of TA was fever, which occurred in 17 patients (89%) with temperatures over 38 degrees C. None of the patients died due to any treatment-related toxicities, but 2 patients (10%) died within 1 month due to disease progression. A CR was achieved in 7 patients (33%), 3 of whom were MDS and 4 AML. A partial remission was reported in 8 patients (38%), no change of disease in 2 patients (10%) and progressive disease in 4 patients (19%). The median remission duration was 18 weeks (range 2-161 weeks) for MDS patients and 11 weeks (range 2-49 weeks) for AML patients. The time to progression for patients of 60 years and older (n = 10) was 16 weeks (range 2-49 weeks) and the survival was 32 weeks (range 2-119 weeks). TA is a feasible and efficacious chemotherapeutic combination for the treatment of MDS RAEB, RAEB-t, CMML and AML. For patients of 60 years and older, this regimen is also a safe option.

Acute Disease↗

PubMed2003

Familial polycythemia vera with Budd-Chiari syndrome in childhood.

Polycythemia vera is a myeloproliferative disorder that, in most cases, occurs sporadically with a median age at presentation of 60 years. Familial cases are very rare and usually manifest in elderly family members. The Budd-Chiari syndrome, characterized by the obstruction and occlusion of the suprahepatic veins, is a rare typical complication in polycythemia vera patients. To date, only two children or adolescents with polycythemia vera and Budd-Chiari syndrome have been described. Here, we report an 11-year-old girl with Budd-Chiari syndrome as the initial symptom of familial polycythemia vera, which was also found in the girl's grandmother. Details of the diagnostic procedures used and the clinical course are reported. The patient underwent orthotopic liver transplantation and is being treated with hydroxyurea. The available literature on familial polycythemia vera and polycythemia vera in childhood with and without Budd-Chiari syndrome is reviewed.

Bone Marrow↗

PubMed2003

Frequency of kidney disease in chronic sarcoidosis.

INTRODUCTION: Sarcoidosis is an immunemediated disease of unknown cause, characterized by noncaseating epithelioid granulomas, affecting multiple organs. Clinically apparent renal involvement is rare and has been documented mostly as case reports. The incidence of renal involvement ranges from 3-23% with a wide spectrum of abnormalities. AIM: The aim of this study was to ivestigate the renal involvement in patients with sarcoidosis. RESULTS: From 1995 to 2002 we diagnosed 46 patients with sarcoidosis. Fifteen patients suffered from acute sarcoidosis with arthritis, mediastinal adenopathy and erythema nodosum (Löfgren's-syndrome). Thirty-one patients had chronic sarcoidosis with organ involvement, such as granulomatous hepatitis, uveitis and pulmonary sarcoidosis. In 15 patients we found renal abnormalities, 10 patients underwent kidney biopsy. Six patients had nephrocalcinosis, 2 patients granulomatous interstitial nephritis, one patient interstitial nephritis without granuloma, and 1 patient suffered from IgA-glomerulonephritis. In 2 patients we found a combination of granulomatous interstitial nephritis either with nephrocalcinosis or with IgA-glomerulonephritis. In all patients the serum creatinine decreased after treatment with corticosteroids. CONCLUSION: In our retrospective analysis we found renal abnormalities in about 48% of patients with chronic sarcoidosis, but never in patients with acute sarcoidosis (Löfgren's syndrome). We conclude that kidney involvement in chronic sarcoidosis is more frequent than previously reported.

Acute Disease↗

PubMedDate not supplied

Adaptive, model-based control by the Open-Loop-Feedback-Optimal (OLFO) controller for the effective fed-batch cultivation of hybridoma cells.

Although fed-batch suspension culture of animal cells continues to be of industrial importance for the large scale production of pharmaceutical products, existing control concepts are still insufficient. Changes in cell metabolism during cultivation and between similar cultivations, the complexity of the cell metabolism, and the lack of on-line state variables restrict the transfer of available control strategies established in bioprocess engineering. A process control strategy designed to achieve optimized process control must account for all these difficulties and fit sophisticated requirements toward adaptability and flexibility. The combination of a fed-batch process and an Open-Loop-Feedback-Optimal (OLFO) control provides a new approach for cell culture process control that couples an efficient cultivation concept to a capable process control strategy. The application of an adaptive, model-based OLFO controller to a hybridoma cultivation and experimental results are presented.

Algorithms↗