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Biomedical subjects

K Burk

Publications and source records attributed to K Burk.

At least 19 recordsLinked to original sources
PubMed2006

Phase II study of MTX-HSA in combination with cisplatin as first line treatment in patients with advanced or metastatic transitional cell carcinoma.

PURPOSE: To assess the efficacy, tolerability and safety of MTX-HSA (methotrexate (MTX) covalently linked to human serum albumin (HSA)) combined with cisplatin as first line therapy for advanced bladder cancer. METHODS: Patients (pat) were treated with a loading dose of 110 mg/m(2) of MTX-HSA followed by a weekly dose of 40 mg/m(2) starting on day 8. Cisplatin was given on day 2 of each 28 day cycle at a dose of 75 mg/m(2). RESULTS: Tumor response evaluation was possible in 7 patients. Complete response (CR) and partial response (PR) was observed in 1 patient each (overall response rate: 29%). Key toxicities included CTC Grade (G) 3/4 stomatitis in 6 patients, vomiting G3 in 1 patient, fatigue G3 in 1 patient and thrombocytopenia G3 in 3 patients. CONCLUSION: The combination of MTX-HSA with cisplatin is feasible and shows antitumor activity against urothelial carcinomas combined with an acceptable toxicity profile.

Adult↗
PubMed2006

The alpha-synuclein gene in multiple system atrophy.

BACKGROUND: The formation of alpha-synuclein aggregates may be a critical event in the pathogenesis of multiple system atrophy (MSA). However, the role of this gene in the aetiology of MSA is unknown and untested. METHOD: The linkage disequilibrium (LD) structure of the alpha-synuclein gene was established and LD patterns were used to identify a set of tagging single nucleotide polymorphisms (SNPs) that represent 95% of the haplotype diversity across the entire gene. The effect of polymorphisms on the pathological expression of MSA in pathologically confirmed cases was also evaluated. RESULTS AND CONCLUSION: In 253 Gilman probable or definite MSA patients, 457 possible, probable, and definite MSA cases and 1472 controls, a frequency difference for the individual tagging SNPs or tag-defined haplotypes was not detected. No effect was observed of polymorphisms on the pathological expression of MSA in pathologically confirmed cases.

Gene Expression↗
PubMed2005

The fragile X tremor ataxia syndrome in the differential diagnosis of multiple system atrophy: data from the EMSA Study Group.

The recent identification of fragile X-associated tremor ataxia syndrome (FXTAS) associated with premutations in the FMR1 gene and the possibility of clinical overlap with multiple system atrophy (MSA) has raised important questions, such as whether genetic testing for FXTAS should be performed routinely in MSA and whether positive cases might affect the specificity of current MSA diagnostic criteria. We genotyped 507 patients with clinically diagnosed or pathologically proven MSA for FMR1 repeat length. Among the 426 clinically diagnosed cases, we identified four patients carrying FMR1 premutations (0.94%). Within the subgroup of patients with probable MSA-C, three of 76 patients (3.95%) carried premutations. We identified no premutation carriers among 81 patients with pathologically proven MSA and only one carrier among 622 controls (0.16%). Our results suggest that, with proper application of current diagnostic criteria, FXTAS is very unlikely to be confused with MSA. However, slowly progressive disease or predominant tremor are useful red flags and should prompt the consideration of FXTAS. On the basis of our data, the EMSA Study Group does not recommend routine FMR1 genotyping in typical MSA patients.

Aged↗
PubMed2003

MRI-based volumetric differentiation of sporadic cerebellar ataxia.

The term idiopathic cerebellar ataxia (IDCA) designates a variety of cerebellar syndromes that may present with a purely cerebellar syndrome (IDCA-C) or with additional extracerebellar features (IDCA-P). Multiple system atrophy is also a sporadic neurodegenerative disorder of unknown origin that may cause prominent cerebellar symptoms (MSA-C). The final neuropathological answer to the question whether IDCA-P and MSA-C represent different varieties of one disease or two distinct entities is still lacking. Three-dimensional MRI-based volumetry allows morphological investigations intra vitam. Volumetric analysis of cerebellum, brainstem and basal ganglia was therefore performed in 46 patients with sporadic cerebellar ataxia and 16 age-matched healthy controls. Patients with dementia were excluded from the study since cognitive impairment is an exclusion criterion for the diagnosis of MSA. Cerebellar patients were clinically divided into two groups: 33 patients with multiple system atrophy with prominent cerebellar symptoms (MSA-C) and 13 patients with extracerebellar features not corresponding to MSA-C (IDCA-P). There was evidence for substantial cerebellar atrophy in both cerebellar groups while additional brainstem atrophy was significantly more pronounced in MSA-C patients. Absolute caudate and putamen atrophy was found to be restricted to single MSA-C individuals while group comparisons of mean volumes did not yield significant differences from controls. Based on the volumetric data, diagnosis could be correctly predicted in 94% of control, 82% of MSA-C and 100% of IDCA-P individuals. The finding of specific imaging characteristics strengthens (i) the value of MRI volumetry in separating MSA-C from other types of sporadic cerebellar ataxia, and (ii) the hypothesis of two independent neurodegenerative disorders in MSA-C and IDCA-P.

Adult↗
PubMed1997

Noise level analysis of commercially available toys.

There have been several isolated reports of hearing loss due to noise levels from toys. Guidelines for noise production by toys is regulated by the Voluntary Product Standards PS 72-76: Toy Safety Act of 1969. To determine the current risk of noise induced hearing loss from toys currently on the market, 25 toys were purchased at a national toy store chain and sound levels were measured at distances approximating ear level (2.5 cm) and a child's arm length (25 cm) from the surface of the toy. Testing revealed peak sound levels ranging from 81 to 126 dBA at 2.5 cm and 80 to 115 dBA at 25 cm from the surface of the toy.

Child↗
PubMed1997

P300 event-related potentials in stutterers and nonstutterers.

This study investigated possible differences between adult stutterers and nonstutterers in the P300 event-related potential. Responses to tonal stimuli were recorded from electrodes placed over the left (C3) and righ (C4) hemispheres. The two groups exhibited different patterns of interhemispheric activity. Although all 8 participants in the fluent group exhibited P300s that were higher in amplitude over the right hemisphere, 5 of the 8 disfluent participants had higher amplitude activity over the left hemisphere. These results provide evidence that stutterers and nonstutterers may exhibit differences between hemispheres in the processing of some types of nonlinguistic (tonal) stimuli.

Adolescent↗
PubMed1996

Pharmacokinetics and pharmacodynamics of the new podophyllotoxin derivative NK 611. A study by the AIO groups PHASE-I and APOH.

NK 611 is a new podophyllotoxin derivative in which a dimethyl amino group replaces a hydroxyl group at the sugar moiety of etoposide. This results in profound physico-chemical differences: NK 611 is much less hydrophobic than etoposide. Preclinical studies have shown that NK 611 is advantageous in terms of bioavailability and of the potency of its anticancer activity. A clinical phase I study was performed in cancer patients within the framework of the AIO. Additionally, its pharmacokinetics and pharmacodynamics were investigated. NK 611 was given to 26 patients at doses ranging from 60 to 140 mg/m2 [maximum tolerated dose (MTD) 120 mg/m2] in a 30-min infusion. Plasma and urine samples were collected from 25 patients and analyzed using a validated high-performance liquid chromatography (HPLC) assay procedure. The concentration versus time curve of total NK 611 in plasma samples was best described by a three-compartment model. The overall median pharmacokinetic values were as follows (ranges are given in parentheses): mean residence time (MRT) 16.5 (5.4-42.3)h, terminal half-life 14.0 (8.2-30.5)h, volume of distribution at steady state (V(ss)) 11.4 (7.9-18.1) l/m2 and plasma clearance (Cl(p)) 15.1 (3.6-36.4) ml min-1 m-2. The total systemic drug exposure, represented by the area under the curve (AUC), varied between 53.4 and 532.0 micrograms ml-1 h. The mean AUC (+/- SD) increased with the dose from 78.7 +/- 3.7 micrograms ml-1 h at 60 mg/m2 up to 202.8 +/- 157.2 micrograms ml-1 h at 120 mg/m2. The mean urinary excretion (UE) fraction of unchanged drug at 48 h after the end of the infusion varied between 3.0% and 25.8% of the total dose delivered. Analysis of ultrafiltrate samples showed a protein binding of approx.. 99%. The percentage reduction in white blood cells (WBC) and neutrophils (ANC) correlated with the dose, AUC, and AUC(free). The best relationship between the percentage of reduction in ANC and a pharmacokinetic parameter (AUC) took a nonlinear Hill-type form. The laboratory parameter for kidney or liver function did not correlate with the AUC. The variation of pharmacokinetic parameters within each dose level was profound. The reason for this pharmacological behavior remains unclear and should be investigated in further studies.

Adult↗
PubMed1995

A trial of lobaplatin (D-19466) in platinum-resistant ovarian cancer.

Long-term survival in epithelial ovarian cancer remains problematic despite multimodality therapy. A fundamental difficulty is the development of tumor resistance to platinum compounds. Analogs have been developed that demonstrate activity in platinum-resistant cell lines both in vitro and in vivo. Lobaplatin (D-19466), a third-generation compound, demonstrates significant activity in carboplatin and cisplatin-resistant cell lines. Lobaplatin was given to 17 assessable patients with platinum-refractory ovarian cancer. The drug was initially administered at a dose of 50 mg/m2 but was later reduced to 40 mg/m2 because of excessive thrombocytopenia. Nine patients required red cell transfusions during therapy. Cycles were repeated every 21-35 days (median cycle length 28 days). No objective responses were observed. Lobaplatin has no activity in platinum-resistant epithelial ovarian cancer.

Adult↗
PubMed1994

Intravesical idarubicin--a phase-I study.

In the scope of a pharmacokinetic and dose-finding study 33 patients received instillations of idarubicin in 11 different doses 1 h before scheduled transurethral resection of bladder cancer. The dose was increased continuously from 5 to 30 mg and the concentration from 0.25-1.5 mg/ml. Idarubicin uptake into tissue was measured along with the serum level. The results showed a clear correlation of the tissue levels with dose and concentration. A significantly higher concentration of idarubicin was measured in the tumor in comparison with the mucosa. Absorption into the muscle was minimal and serum levels were low. Systemic toxicity was not observed, but there were signs of local toxicity in 50% of the subjects. Cytotoxic concentrations in the mucosa were reached at doses of over 15 mg and concentrations of over 0.5 mg/ml. A phase-II study is in preparation.

Administration, Intravesical↗
PubMed1992

Tissue disposition and plasma concentrations of idarubicin after intravesical therapy in patients with bladder tumors.

We studied single doses of intravesical idarubicin (IDA) given as 1-h instillations to 33 patients with bladder tumors. The dose was escalated from 5 to 30 mg and the concentration, from 0.25 to 1.5 mg/ml for evaluation of the importance of both the total amount of drug and the drug concentration on the levels of IDA found in different tissues (tumor, mucosa and muscle). Additionally, plasma uptake over 24 h was studied. The results demonstrated that (1) the levels of IDA in extracts of bladder tumors were significantly higher than those in normal bladder tissue, (2) the incorporation of IDA into tumors depended on the total amount of drug instilled and on the concentration of drug in the instillation fluid, (3) cytotoxic concentrations of IDA were noted in all tumors when the total amount of drug instilled was greater than 15 mg and the drug concentration in the instillation fluid was greater than 0.33 mg/ml, and (4) plasma levels of IDA were negligible.

Administration, Intravesical↗
PubMed1990

Pharmacokinetics and metabolism of iodo-doxorubicin and doxorubicin in humans.

The pharmacokinetics of doxorubicin (DOX), iodo-doxorubicin (I-DOX) and their metabolites in plasma has been examined in five patients each receiving 50 mg/m2 of both anthracyclines as a bolus injection. Terminal half-life, mean residence time (MRT), peak plasma concentration Cmax, and area under the curve (AUC) appeared smaller for I-DOX, whereas its plasma clearance (CLP) and volume of distribution at steady state (Vss) were larger than for DOX. The major metabolite of I-DOX was iodo-doxorubicinol (I-AOL) followed by doxorubicinol aglycone (AOLON). The AUC of I-AOL was 6-times larger than that of its counterpart AOL, which is the major metabolite of DOX. AOLON generated after I-DOX administration is a further important metabolite, as its AUC was 10-times larger than that of AOLON generated from DOX. The other aglycones, such as doxorubicin aglycone (AON) and the 7-deoxy-aglycones were only minor metabolites after either I-DOX or DOX injection. The ratio AUCI-AOL/AOL/AUCI-DOX/DOX was 27 in the case of I-DOX and 0.4 after DOX. The terminal half-lives of the cytostatic metabolites I-AOL and AOL were similar, although a longer MRT for AOL was calculated. Both metabolites had much longer MRTs than their parent drugs. The MRTs of the aglycones AOLON and AON were greater than those of the 7-deoxy-aglycones after both I-DOX and DOX. Approximately 6% DOX and less than 1% I-DOX were excreted by the kidneys during the initial 48 h. About 5% of I-DOX was excreted via the kidneys as I-AOL. Aglycones were not detected in significant amounts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Toxicity, pharmacokinetics and metabolism of iododoxorubicin in cancer patients.

25 patients, mostly pretreated, received 55 courses of iododoxorubicin as a single intravenous bolus every 2 weeks. The starting dose was 2 mg/m2 with seven steps to reach the dose-limiting toxicity level. 3 patients treated with 90 mg/m2 had WHO grade 4 myelotoxicity; 2 of these patients had not had cytostatic chemotherapy. 3 of 7 patients treated with 75 mg/m2 had grade 3-4 myelotoxicity; 4 had grade 1-2. Non-haematological toxicities were minor. Acute cardiotoxicity and objective tumour responses were not observed. Plasma and urine levels of iododoxorubicin and five metabolites were assayed in 16 patients. Metabolism to iododoxorubicinol was rapid and plasma clearance was dose-dependent and rapid. Plasma levels and the area under the curve for iododoxorubicin increased with dose. The mean residence time was 3.9 h in patients without liver metastasis and 10.4 h in patients with liver metastasis. Renal excretion was minor. The maximally tolerated dose was 90 mg/m2.

Adult↗
PubMed1990

High dose epirubicin in refractory or relapsed non-seminomatous testicular cancer: a phase II study.

Sixteen patients with metastatic nonseminomatous testicular cancer refractory to cisplatinum combination chemotherapy, were treated with epirubicin 100-120 mg/m2 q d 22. One partial remission lasting 6 months was achieved. Two additional patients had stabilisation of disease for 3 and 4 months. Median time to progression was 43 days. Myelosuppression was dose-limiting, with a WBC nadir of 1900/microliters. 4/30 cycles (13%) were associated with granulocytopenic fever. One patient developed a decline in cardiac ejection fraction without clinical signs of congestive heart failure. Epirubicin in this dosage and schedule has no major therapeutic activity in heavily pretreated non-seminomatous testicular cancer.

Combined Modality Therapy↗
PubMed1990

[Iodo-doxorubicin, a new anthracycline derivative. Current state of progress].

Iodo-doxorubicin belongs to the group of doxorubicin analogs with modifications at the 4'-position of the daunosamine sugar moiety. Epirubicin is the archetype of the analogs created by configurational changes at the sugar. In case of EPI, the hydroxy group at the 4'-position is equatorial instead axial. In case of I-DOX, the hydroxy group has been replaced by an iodine-atom. This exchange has a great influence on the basicity of the amino group at the 3'-position. The physico-chemical properties of I-DOX are markedly different from those of DOX and EPI. I-DOX is unprotonated at physiological pH and much more lipophilic than DOX. The preclinical screening showed greater potency of I-DOX in different tumor cell systems. Cardiotoxicity and tissue toxicity after extravasation were significantly reduced in case of I-DOX. The substance was evaluated within three phase-I-studies in Europe during 1988 to 1990. The most prominent toxicity observed was myelotoxicity. This type of toxicity was dose-dependent and reversible. Alopecia, stomatitis/mucositis were not seen at all. There was only minor nausea without vomiting. The measured thyroid parameters were not affected by administration of an iodine-containing drug, but long-term effects cannot be ruled out. No acute cardiotoxicity was observed. The pharmacokinetics and metabolism of I-DOX differ from those of DOX and EPI. The terminal half-life of I-DOX is shorter, the plasma clearance higher than of DOX. One major difference is the formation of iodo-doxorubicinol, which is much larger in case of I-DOX compared to DOX and EPI. This cytostatic metabolite has a long terminal half-life.

Animals↗
PubMed1990

Weekly chemotherapeutic regimen in metastatic prostate cancer.

1. A weekly fractionation of EPIRUBICIN at an unchanged dose intensity leads to a significant decrease in toxicity. 2. The weekly administration of 25 mg/m2 EPIRUBICIN is effective in treating hormone refractory prostate carcinoma and completely fulfills the requirements for palliation.

Antineoplastic Agents↗