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H P Kraemer

Publications and source records attributed to H P Kraemer.

At least 19 recordsLinked to original sources
PubMed1995

Structure-activity relationships of phenyl- and benzoylpyrroles.

Antitumor, antimicrobial, and phytotoxic activities of the marine antibiotic pentabromopseudilin (1a) and related phenyl-, benzyl- and benzoyl pyrroles were compared. All activities depended strongly on the substituent pattern, with the natural compound 1a being the most active one. As judged from model reactions, a covalent bond of nucleophiles to the pyrrole system may be involved in the inhibition of macromolecular syntheses.

Animals↗
PubMed1993

Synthesis and antitumor activity of isodoxorubicin analogues.

The synthesis and biological activity of the new 4-demethoxyanthracyclines 15, 22, and 23 are reported. They were obtained from synthetic 9-deacetyl-9-(hydroxymethyl)-4-demethoxydaunomycinone (isopropylidene derivative 9) and from 4-azido- or 4-amino-2,4,6-trideoxy-L- lyxo-hexoses. Anthracycline 22 (hydrochloride salt), the most active compound in the series, was slightly more potent than doxorubicin in vitro against three cell lines (L1210, HT29, A549). It was found to exhibit similar antitumor activity in vivo (iv route) against L1210 leukemia, but was less active than doxorubicin against three human tumors in a subrenal capsule assay LXF, A549, and HT29).

Animals↗
PubMed1992

The MTT assay for chemosensitivity testing of human tumors of the central nervous system. Part I: Evaluation of test-specific variables.

The aim of this study was to optimize the experimental conditions of the MTT assay for primary cultures of human brain tumors. This assay is based on the mitochondrial reduction of MTT-(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) salt to formazan crystals by living cells. Formazan can be quantified spectrophotometrically. This assay measures the antimetabolic and, by using an adequate recovery period for the cells, also the antiproliferative effects of cytotoxic drugs. Our results suggest the following experimental design for its application as an chemosensitivity assay for human brain tumors: 1-h drug exposure followed by a seven days recovery period without drugs. Then tumor cells are incubated 4 hours with 1 mg MTT/ml and final absorbance readings are performed at 550 nm and 630 nm as test and reference wavelengths respectively. In this way, the assay seems to be a reliable and simple method for rapid chemosensitivity testing in human brain tumors.

Antineoplastic Agents↗
PubMed1992

The MTT assay for chemosensitivity testing of human tumors of the central nervous system. Part II: Evaluation of patient- and drug-specific variables.

In this study we assessed the influence of patient- and drug-specific parameters in the short-term MTT-chemosensitivity assay in 150 primary cell cultures derived from human brain tumors. In 45 patients the MTT assay was directly compared with the CFA (Colony Forming Assay). Resistance was 10-20% higher in the MTT assay than in the CFA, but there was a good agreement in both assays, that more malignant gliomas had a higher in vitro chemosensitivity against ACNU and BCNU. Overall the results demonstrate, that there is no uniform correlation between the in vitro chemosensitivity and the histopathological classification of the tumors, which corresponds well to the clinical situation. On the basis of this study we suggest prospective clinical trials with the MTT assay in human brain tumors.

Antineoplastic Agents↗
PubMed1990

Semisynthetic epsilon-isorhodomycins: their synthesis using glycals and their structure-activity relationship.

Syntheses and structure-activity relationships of 7-O-(3-amino-2,3,6-trideoxy-a-L-lyxo- (18), -L-arabino- (20) and -L-ribo- hexopyranosyl)-epsilon-isorhodomycins (25) and their 3'-dimethylamino derivatives 22, 23 and 26 are described. Condensation (trimethylsilyl triflate, molecular sieves 4 A, 10:1 dichloromethane-acetone, -15 degrees) of epsilon-isorhodomycinone (epsilon-isoRMN, 6) with 1,5-anhydro-4-O-p-nitrobenzoyl-3-trifluoroacetamido-L-lyxo- (5) -L-arabino- (9) or -L-ribo-hex-l-enitols (10) afforded mainly the 7-O-a-glycosyl-epsilon-isoRMNs 7, 11, and 12. Similar glycosylation of 6 with 1,5-anhydro-3-azido-4-O-p-nitrobenzoyl-2,3,6-trideoxy-L-arabino-hex-1-++ +enitol (15) yielded a-glycoside 16. Removal (M NaOH) of the p-nitrobenzoyl and trifluoroacetyl groups from 7, 11, and 12 gave the 7-O-(3-amino-2,3,6-trideoxy-a-L-hexopyranosyl)-epsilon-isoRMNs 18, 20, and 25. Reductive alkylation (CH2O, NaCNBH3) of these products afforded the 3'-N,N-dimethyl analogues 22, 23, and 26. The cytotoxic effect (IC50) of the semisynthetic epsilon-isorhodomycins was tested in vitro in leukemia cell line L1210.

Animals↗
PubMed1990

Sensitivity of human malignant intracranial tumors against MCNU in vitro in comparison to ACNU and BCNU.

An in vitro chemosensitivity test was carried out in 50 specimen of human malignant intracranial tumors. Aim of the study was to evaluate the proportion of sensitivity against MCNU (Ranomustine) in comparison to ACNU and BCNU. 47 tests were evaluable. Mean viability of the specimen was 83.3 +/- 18.7%, mean plating efficiency was 0.068 +/- 0.051%. 9/47 settings revealed sensitivity against MCNU in vitro (ACNU: 10/47; BCNU: 16/46). There was no advantage of MCNU concerning age or sex of the patients. Brain metastases seemed to be slightly more frequent sensitive against MCNU than primary brain tumors. Cross resistance between ACNU, BCNU and MCNU was rather high. The results of this in vitro series do not encourage a clinical trial of MCNU as an alternative to the commonly used nitrosoureas.

Aged↗
PubMed1990

Structure-activity relationship of anthracyclines in vitro.

The cytotoxic activities of several natural and semisynthetic anthracyclines against L1210 leukemia and two human colon tumor cells (Colon 4, HT 29) in vitro were examined after short (1 h) and long (7 days) incubation times and correlated with the water/octanol partition coefficients and the DNA-binding affinity of the compounds. Analysis of equation in which cytotoxicity against L1210 (1-h incubation) was parabolically related to the partition coefficient revealed an almost exclusive correlation (r = 0.80) between the cytotoxicity and the parameters, and this correlation was only slightly improved by addition of DNA-binding affinity (r = 0.85). On the other hand, cytotoxic activities displayed after continuous incubation were partially related to both partition coefficients (parabolic dependence) and DNA-binding affinities (linear dependence). In this case the correlation between the activity and partition coefficient (r = 0.67) was significantly improved by addition of DNA-binding affinity (r = 0.90). Similar results were also obtained for human colon tumor cells although the corresponding correlation coefficients were generally of lower value, indicating that cytotoxic activity of anthracyclines against these primary resistant cells may be influenced by additional factors not yet determined.

Animals↗
PubMed1990

Erythropoietin for the treatment of anemia of malignancy associated with neoplastic bone marrow infiltration.

This clinical trial was performed to study the effects of intravenously (IV) administered recombinant human (rh) erythropoietin (EPO) at escalating doses (150, 300, and 450 U/kg, administered as an IV bolus injection, twice weekly, for 6, 4, and 4 weeks, respectively) in five patients with low-grade non-Hodgkin's lymphoma (Ig NHL) and bone marrow involvement and one patient with multiple myeloma (MM). All patients were anemic due to underlying disease. None of the patients had a history of bleeding, hemolysis, renal insufficiency, or other disorders causing anemia in addition to bone marrow infiltrating malignancy. Endogenous EPO serum levels were significantly increased in all patients (74 to 202 mU/mL). Five patients (one MM, four small-cell lymphocytic [SCLC] NHL) showed a dramatic increase of hemoglobin (Hb), hematocrit (Hk) and RBC count becoming obvious on the second EPO dose level. Initial ferritin serum values, which were high mostly due to polytransfusion, were significantly reduced in responding patients. Erythropoiesis of one patient with extensive follicular mixed (fm) NHL did not respond to EPO treatment. Platelet (PLT) count increase (greater than 75% above starting levels) during and following EPO therapy was observed in one patient with MM. Adverse events due to EPO therapy have not been recorded. These findings point out a previously unrecognized capacity of EPO given at pharmacologic doses to stimulate erythropoiesis in patients with anemia due to bone marrow infiltration by neoplastic lymphocytes in spite of enhanced endogenous EPO expression.

Aged↗
PubMed1989

Phase I studies of rodorubicin single bolus and daily times five, once every three weeks in patients with advanced solid tumors.

Rodorubicin (Cytorhodin S, HLB 817) is a new tetraglycosidic anthracycline with interesting preclinical antitumor activity. We have performed two sequential phase I studies with the drug. In the first study Rodorubicin was administered as a single i.v. administration over 30-360 min, once every 3 weeks. The second study concerned a daily times five i.v. bolus schedule. Thirty patients entered these studies. Regardless of schedule, the dose limiting toxicity appeared to be proteinuria, which was reversible after discontinuation of the drug. Phlebitis was a cumbersome side-effect and it was initially considered to determine the MTD in the once every 3 weeks schedule, but finally it could be prevented by giving the drug as a bolus injection into a rapidly running infusion. Nausea and vomiting were infrequent and mild. Neither myelotoxicity nor alopecia were observed. However, even at low cumulative doses the drug was found to be cardiotoxic using both schedules of administration. Seven out of 12 patients developed grade 1-3 cardiotoxicity, most of them above a cumulative dose of more than 4000 micrograms/m2. These side-effects preclude a dose recommendation for phase II studies with these schedules.

Adult↗
PubMed1988

Rodorubicin, a new tetraglycosidic anthracycline.

Rodorubicin is a new tetraglycosidic anthracycline, which was detected because of its activity against human tumors in a human tumor based screening system. Rodorubicin is not active in the typical animal transplantation tumors and might therefore be a new leading structure with preferential activity against slow proliferating human tumors. In spite the fact that Rodorubicin is a chemical anthracycline, the drug has an untypical spectrum of activity and toxicity when compared to standard anthracyclines. The drug is not toxic to bone marrow in animals or humans, however, the dose limiting toxicity is delayed nephrotoxicity in all species, starting with proteinuria and finally clearance reduction. Rodorubicin might be an interesting new candidate for further clinical evaluation and is the first drug being developed clinically in spite its inactivity in animal transplantation tumor systems.

Animals↗
PubMed1986

Human tumor testsystems: a new screening approach.

Recently, a new screening system which is mostly based on the use of human tumor material has been developed. This system uses various in vitro or in vivo test systems, such as the human tumor clonogenic assay, the subrenal capsule assay and the human tumor xenograft model to evaluate the potential clinical effectiveness of new drugs on human tumors. The predictive value of those test systems indicated by a reasonable correlation between test results and clinical activity has been shown in retrospective and even prospective clinical trials. To overcome the tumor heterogeneity and to circumvent the questionable preselection of drugs using fast proliferating tumors, this human tumor based test system uses a broad panel of slow proliferating human tumors which are established in nude mice to allow repeated tests. Recently some drugs being preferentially active in this human tumor based test system which are at the same time only marginally active in the usual NCI animal tumor screening system have been developed.

Animals↗
PubMed1985

Aclarubicin: experimental and clinical experience.

Aclarubicin, discovered by Umezawa in 1975, is a new cytostatic anthracycline antibiotic. It is one of the anthracyclines with the lowest cardiotoxicity, it is not mutagenic and it stimulates differentiation of tumour cells. The therapeutic index of aclarubicin (efficacy related to toxicity) is higher than that of doxorubicin and daunorubicin, using a proper dose schedule. Single dose therapy of aclarubicin shows only marginal efficacy, whereas multiple divided dose therapy exhibits efficacy comparable to that of doxorubicin and daunorubicin. Thus for clinical trials two dose schedules were designed: 25 mg/m2/day, days 1-7 for acute leukaemia; and 30 mg/m2/day, days 1-4 for solid tumours. Aclarubicin was shown to be highly active in acute leukaemia with 58% complete remissions in first relapse of AML. Good results were also seen in acute leukaemia in combination with cytosine arabinoside and thioguanine. In clinical trials with breast cancer and thyroid cancer the efficacy was in the same range as would be expected for doxorubicin, but side-effects were markedly reduced. Anorexia, mild nausea and infrequent vomiting were observed. Myelosuppression was common but dose reduction was not necessary. There was no alopecia and no congestive heart failure.

Aclarubicin↗
PubMed1984

[The pathology of susceptibility to hurt feelings].

Working from a survey of the psychoanalytical literature, this paper develops the thesis of a specific pathology of the susceptibility to feeling hurt. Susceptibility to feeling hurt and the state of feeling hurt are described first by listing definite symptoms and deficient forms of coping. The characteristics of heightened susceptibility to feeling hurt are compiled on the basis of various psychodynamic interpretations and in the terminology of the psychoanalytical theory of neuroses. Symptoms, deficient forms of coping and psychodynamic methods of interpretation are then related to the four levels of experiencing urge. From this, finally, the thesis of a specific pathology of the susceptibility to feeling hurt is derived as characterized by a group of specific inhibitions and attitudes.

Ego↗