Search PubMed⌕ Search

Biomedical subjects

K Kramer

Publications and source records attributed to K Kramer.

At least 91 records · Page 5Linked to original sources
PubMed1997

Correlation of MYCN amplification, Trk-A and CD44 expression with clinical stage in 250 patients with neuroblastoma.

In contrast to MYCN amplification, expression of either trk-A or CD44 in neuroblastoma is a favourable prognostic factor and were therefore investigated in tumours from 250 patients. One hundred and eleven localised/4s (Group 1) and 139 stage 4 (Group 2) tumours were analysed. MYCN copy number was obtained by Southern blotting or PCR amplification and was detected in 28 stage 4 tumours. Trk-A and CD44 expression was detected by immunoperoxidase staining using murine monoclonal antibodies 5C3 and L178, respectively. Expression was scored as positive (homogeneous), mixed (heterogeneous) or non-reactive (negative). Trk-A expression was found in 95% of Group 1 tumours and 49% of Group 2 tumours. CD44 expression was found in 100% of Group 1 tumours, the majority of which had a strong homogeneous expression. Lack of CD44 expression occurred in 25% of tumours, all stage 4 neuroblastoma. Of the 28 MYCN amplified tumours, 27/28 (96%) were trk-A negative, and 13/28 (46%) CD44 negative. We conclude that (1) a significant percentage of stage 4 neuroblastoma express either or both trk-A and CD44, (2) the absence of CD44 expression is highly restricted to stage 4 neuroblastoma and is associated with the lack of trk-A expression, (3) trk-A negativity among CD44-positive tumours is associated with stage 4 neuroblastoma and (4) the absence of trk-A expression is highly correlated with MYCN amplification.

Carrier Proteins↗
PubMed1997

Survival from non-stage 4 neuroblastoma without cytotoxic therapy: an analysis of clinical and biological markers.

The clinical characteristics of 43 patients (pts) and the biological features of their non-stage 4 neuroblastoma (11, 3, 15, 7 and 7 with stages 1, 2A, 2B, 3 and 4S, respectively) all managed initially without cytotoxic therapy at Memorial Sloan-Kettering Cancer Center are summarised. We staged patients by the International Neuroblastoma Staging System and measured their urine and serum tumour markers. Tumour MYCN copy number, chromosomal ploidy, chromosome 1p deletion, Shimada histopathology, trk-A and CD44 expression were analysed. Among patients with localised tumour (n = 36), 13 had residual disease after initial surgery, 19 had regional lymph node invasion and 6 had epidural involvement (2 of 6 being paraplegic). All 7 stage 4S patients had liver tumours, 3 had bone marrow involvement and 3 had lymph node involvement. The most common adverse biological markers were unfavourable histopathology (9/40 evaluable tumours) and diploidy (7/39 tumours tested). At a median follow-up of 50+ months, 42 patients are alive and well (5 with evidence of disease), and 1 patient in remission died of encephalopathy. Progressive/recurrent disease occurred in 12 patients, 1 stage 2A, 2 stage 2B, 4 stage 3 and 5 stage 4S. Chemotherapy was eventually used in 4 patients: a 3-year-old stage 2B patient who developed stage 4; a 2-year-old whose recurrent tumour had poor-risk biological markers; a 1-year-old whose recurrent stage 3 disease infiltrated a vertebral body and a stage 4S infant with respiratory impairment from progressive hepatomegaly. Three of the treated patients had diploid tumours. We conclude that non-stage 4 is of itself a strong predictor of a favourable outcome. Diploidy, unfavourable histopathology and unresectable tumours were associated with disease progression. However, evolution of local-regional tumour into distant metastatic stage 4 disease is not typical of neuroblastoma.

Biomarkers, Tumor↗
PubMed1997

Pharmacokinetics and acute toxicology of intraventricular 131 I-monoclonal antibody targeting disialoganglioside in non-human primates.

Tumors metastatic to the leptomeninges are often incurable despite current aggressive treatment modalities. Regional therapy by intrathecal administration of monoclonal antibodies (MoAbs) can maximize their concentration to tumor sites while reducing systemic toxicities. Anti-GD2 antibody 3F8 has successfully targeted human neuroectoderm derived tumors. Disialoganglioside GD2 expression in the central nervous system is identical between humans and cynomolgus monkeys. We studied the pharmacokinetics and the acute and subacute toxicities of intraventricular 131I-3F8 in 8 cynomolgus monkeys. Four animals were purposely immunized with intravenous 3F8 administered 2-4 weeks prior to injections. All animals remained clinically stable. Toxicities included weight loss, fever and CSF leukocytosis. One animal developed a left-sided hemiparesis following his seventh injection, presumably due to a local drug accumulation in the setting of an intermittently patent catheter. The estimated radiation dose to the CSF was 19-48 Gy in the immunized monkeys and 19-82 Gy in the nonimmunized monkeys, and to blood was 0.11-0.98 Gy and 0.29-2.03 Gy, respectively. Histopathology revealed chronic reactive changes adjacent to the region of catheter placement and a focal vasculitis in 2 animals. Peripheral blood counts and bone marrow examinations remained normal. Because of the blood-brain barrier, CSF monkey-anti-mouse antibody titers were less than 10 per cent of those in the serum. In contrast to the CSF radioactivity clearance which was similar in all animals, blood clearance was substantially accelerated in 3F8-immunized animals versus controls. Correspondingly, the CSF to blood dose ratio was improved 1.3 to 6.6 fold (mean 3.5). We conclude that intraventricular administration of 131I-3F8 in primates is tolerable. It can deliver very high doses of radiation to the CSF space with minimal toxicity to blood and bone marrow. Serum anti-mouse antibody accelerates the clearance of 131I-3F8 in blood and may improve the therapeutic index.

Animals↗
PubMed1997

Monohydroxyethylrutoside, a dose-dependent cardioprotective agent, does not affect the antitumor activity of doxorubicin.

The cumulative dose-related cardiotoxicity of doxorubicin is believed to be caused by the production of oxygen- free radicals. 7-Monohydroxyethylrutoside (monoHER), a semisynthetic flavonoid and powerful antioxidant, was investigated with respect to the prevention of doxorubicin-induced cardiotoxicity in mice and to its influence on the antitumor activity of doxorubicin in vitro and in vivo. Non-tumor-bearing mice were equipped with a telemeter in the peritoneal cavity. They were given six weekly doses of 4 mg/kg doxorubicin i.v., alone or in combination with either 100 or 250 mg/kg monoHER i.p., 1 h prior to doxorubicin administration and for the following 4 days. Cardiotoxic effects were measured from electrocardiogram changes up to 2 weeks after treatment. Protection against cardiotoxicity was found to be dose dependent, with 53 and 75% protection, respectively, as calculated from the reduction in the increase in the ST interval. MonoHER and several other flavonoids with good antioxidant properties were tested for their antiproliferative effects in the absence or the presence of doxorubicin in A2780 and OVCAR-3 human ovarian cancer cells and MCF-7 human breast cancer cells in vitro. Some flavonoids were directly toxic at 50 and 100 microM, whereas others, including monoHER, did not influence the antiproliferative effects of doxorubicin at these concentrations. The influence of monoHER was further tested on the growth-inhibitory effect of 8 mg/kg doxorubicin i.v., given twice with an interval of 1 week in A2780 and OVCAR-3 cells that were grown as s.c. xenografts in nude mice. MonoHER, administered 1 h before doxorubicin in a dose schedule of 500 mg/kg i.p. 2 or 5 days per week, was not toxic and did not decrease the antitumor activity of doxorubicin. It can be concluded that monoHER showed a dose-dependent protection against chronic cardiotoxicity and did not influence the antitumor activity of doxorubicin in vitro or in vivo.

Animals↗
PubMed1996

Doxorubicin-induced cardiotoxicity monitored by ECG in freely moving mice. A new model to test potential protectors.

In laboratory animals, histology is most commonly used to study doxorubicin-induced cardiotoxicity. However, for monitoring during treatment, large numbers of animals are needed. Recently we developed a new method to measure ECG values in freely moving mice by telemetry. With this model we investigated the effect of chronic doxorubicin administration on the ECG of freely moving BALB/c mice and the efficacy of ICRF-187 as a protective agent. The ST interval significantly widened from 15.0 +/- 1.5 to 56.8 +/- 11.8 ms in week 10 (7 weekly doses of 4 mg/kg doxorubicin given i.v. plus 3 weeks of observation). The ECG of the control animals did not change during the entire study. After sacrifice the hearts of doxorubicin-treated animals were enlarged and the atria were hypertrophic. As this schedule exerted more toxicity than needed to investigate protective agents, the protection of ICRF-187 was determined using a dose schedule with lower general toxicity (6 weekly doses of 4 mg/kg doxorubicin given i.v. plus 2 weeks of observation). On this schedule, the animals' hearts appeared normal after sacrifice and ICRF-187 (50 mg/kg given i.p. 1 h before doxorubicin) provided almost full protection. These data were confirmed by histology. The results indicate that this new model is very sensitive and enables monitoring of the development of cardiotoxicity with time. These findings result in a model that allows the testing of protectors against doxorubicin-induced cardiotoxicity as demonstrated by the protection provided by ICRF-187.

Analysis of Variance↗
PubMed1996

Prognostic value of TrkA protein detection by monoclonal antibody 5C3 in neuroblastoma.

The effects of nerve growth factor, a neurotrophin mediating growth and differentiation of neural crest-derived cells, are mediated by the receptor TrkA. TrkA mRNA expression has been associated with a good prognosis in human neuroblastoma (NB). We describe the use of monoclonal antibody 5C3 in detecting TrkA expression by immunohistochemistry in NB and other malignant tumors. A murine anti-TrkA IgG1 monoclonal antibody, 5C3, was generated against the extracellular domain of human p140(TrkA). 5C3 detected a 140-kDa band on Western blots. 5C3 was optimized for immunostaining and used to detect p140(TrkA) on 113 frozen NB samples and 42 samples from nine other malignancies. MOPC21 IgG1 antibody was used as a control. Results by immunohistochemistry were compared to TrkA expression assessed by reverse transcription-PCR and Western analysis. The prognostic value of TrkA expression by these methods was evaluated and compared to other known prognostic variables, including stage, age, and MYCN copy number. TrkA expression was detected by immunohistochemistry in 73 of the 113 NB tumor specimens and strongly correlated with nonmetastatic disease. TrkA expression was specific for NB among small round blue cell tumors. Both TrkA expression by immunohistochemistry and localized/4s disease correlated with survival. Tumors from 55 of 60 patients with localized/4s NB exhibited homogeneous or a mixed pattern of TrkA immunohistochemistry, whereas only 18 of 53 patients with stage 4 NB were immunoreactive. Detection of TrkA by reverse transcription-PCR and Western analysis was much more sensitive and no longer correlated with survival. 5C3 enables rapid detection of p140(TrkA) by immuno-histochemistry and identifies patients more likely to have localized NB with a favorable clinical outcome. Lack of TrkA expression is correlated with metastatic, malignant NB. A subset of patients with NB, however, died of aggressive metastatic disease despite TrkA expression. As a mimic of nerve growth factor, 5C3 may be useful in the study of TrkA-expressing tumors.

Antibodies, Monoclonal↗
PubMed1995

Effect of dimethyl sulfoxide (DMSO) on the electrocardiogram (ECG) in freely moving male Balb/c mice.

1. Since dimethyl sulfoxide (DMSO) is a solvent which is often used for drugs in animal studies, we investigated the effect of a daily administration of DMSO on the telemetrically obtained electrocardiogram (ECG) in freely moving male Balb/c mice. 2. During treatment with 4.5 ml 100% DMSO/kg i.p. 5 days per week during 3 weeks, DMSO caused substantial cardiotoxicity. The ST-interval increased significantly after 1 week by 2.2 +/- 1.3 msec and also the ECG wave form changed completely in time. 3. During treatment with 4.5 ml 50% DMSO/kg i.p. 5 days per week during 3 weeks, no significant difference was observed compared with the control animals. 4. During the entire study the maximal heart rate and body weight remained constant in all treated groups. 5. The data indicate that DMSO can not be used in a 100% concentration to dissolve compounds that are tested for protection against the cardiotoxicity of cytostatics.

Animals↗
PubMed1995

Monohydroxyethylrutoside as protector against chronic doxorubicin-induced cardiotoxicity.

1. The clinical use of the antitumour agent, doxorubicin, is largely limited by the development of a cumulative dose-related cardiotoxicity. This toxicity is generally believed to be caused by the formation of oxygen free radicals. In earlier studies it was established that flavonoids, naturally occurring antioxidants, can provide some degree of protection. In this study we investigated whether 7-monohydroxyethylrutoside (monoHER), a powerful antioxidative flavonoid with extremely low toxicity, can provide protection to an extent comparable to the clinically successful Cardioxane (ICRF-187). 2. Balb/c mice of 20-25 g were equipped i.p. with a telemeter to measure ECG. They were given 6 i.v. doses of doxorubicin (4 mg kg-1) at weekly intervals. ICRF-187 (50 mg kg-1) or monoHER (500 mg kg-1) were administered i.p. 1 h before doxorubicin administration. In the 2 monoHER groups the treatment continued with either 1 or 4 additional injections per week. A saline and monoHER treated group served as controls. After these 6 weeks, they were observed for another 2 weeks. 3. At the end of this study (week 8) the ST interval had increased by 16.7 +/- 2.7 ms (mean +/- s.e. mean) in doxorubicin-treated mice. At that time, the ST interval had increased by only 1.8 +/- 0.9 ms in ICRF-187 co-mediated mice and in monoHER co-medicated mice by only 1.7 +/- 0.8 and 5.1 +/- 1.7 ms (5- and 2-day schedule, respectively, all P < 0.001 relative to doxorubicin and not significantly different from control). The ECG of the control animals did not change during the entire study. The QRS complex did not change in either group.4. It can be concluded that monoHER protects against doxorubicin-induced cardiotoxicity and merits further evaluation in this respect.

Animals↗
PubMed1995

The use of telemetry to record electrocardiogram and heart rate in freely swimming rats.

Measurement of parameters from the circulatory system of laboratory animals can play an important role in pharmacological or toxicological research. To study the mutual interaction between physical exercise and antioxidant systems in rats, we selected swimming as a model for exercise performance. Swimming belongs to the natural behavior of the rat, and under proper experimental conditions, it primarily involves physical exercise with little emotional arousal. Therefore, we developed a swimming basin in which the intensity of exercise could be manipulated through speed and duration of swimming. A laser beam interruption system enables the rat to be followed during each swimming session. A motor-controlled following device, consisting of a rail and sledge connected to a position sensor, contains an antenna mounted in a receiver board. In this way, we can record the electrocardiogram (ECG) and heart rate (HR) with a commercially available telemetry transmitter implanted in the peritoneal cavity of freely swimming rats and evaluate the physical fitness (condition) of the swim-trained rats.

Animals↗
PubMed1994

In vitro release of [3H]5-hydroxytryptamine from fetal and maternal brain by drugs of abuse.

Cortical synaptosomes were prepared from pregnant dams (GD-17) and rat fetuses (ED-17), loaded with [3H]5-HT and assayed to evaluate release mediated by cocaine (COC), fenfluramine (FEN) and 3,4-methylenedioxymethamphetamine (MDMA). COC and FEN elicited a high-affinity (10(-9) M) release response in fetal tissue which was not apparent in the dam. MDMA-induced release was similar in magnitude in both tissue types. Consequently, the release of 5-HT from developing neurons may be one mechanism by which COC and FEN elicit their teratogenetic effects in utero.

3,4-Methylenedioxyamphetamine↗
PubMed1994

The involvement of nitric oxide synthase in the effect of histamine on guinea-pig airway smooth muscle in vitro.

The influence of histamine on nitric oxide synthase (NOS) in the development of airway smooth muscle hyperresponsiveness to histamine was investigated in vitro. In the absence of histamine, NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) had no significant effect on the basal tone. However, precontraction of the tissues with histamine (0.3 microM) resulted in a significant contractile response to L-NAME in the preparations with intact epithelium. Removal of the epithelial layer decreased the responses to L-NAME. L-arginine could partially reverse the contraction produced by L-NAME. L-NAME enhanced the maximal response to histamine, but the sensitivity of the tracheal smooth muscle to histamine was not affected. These results suggest that, in the airway, histamine can activate NOS, resulting in the release of nitric oxide. The latter may be regarded as a local negative modulator to maintain the tissue in a physiological homeostasis.

Amino Acid Oxidoreductases↗
PubMed1994

Community nursing in Belgium, Germany and The Netherlands.

This paper contains a comparative study on community nursing in the Netherlands, Belgium and Germany, carried out in the region around Maastricht, where the borders of the three countries meet. The well-known problem of comparative studies (the incomparability of concepts and data) has been solved by using the same measuring instruments in the three countries. The comparison between the countries was on three aspects: the level of care dependency of the patients, the type and number of services provided and the nurses' job interpretation and job satisfaction. During 1 week in June or September 1991, 89 community nurses made records of all their home visits and nursing activities. In total the community nurses paid 5165 home visits to provide care to 1796 patients. The results indicate that both the level of care dependency of the patients as well as the type of care provided differs between the three countries. Belgian community nurses have the highest number of patients with a high level of care dependency. Curative services like technical nursing care and domestic care are most frequently provided by the German and Belgian community nurses. Informing, educating and supporting care is most frequently provided by the Dutch community nurses. The German community nurses spend less time on administration activities. With respect to job interpretation and job satisfaction the following results were found. The Dutch community nurses mentioned in their job interpretation many more preventive tasks, whereas the German community nurses more often mentioned domestic tasks. Concerning the hygienic and technical tasks, no significant differences were found between the three countries. Finally, job satisfaction is lowest in the Netherlands. Dutch community nurses are less satisfied with the work organization and the possibilities of autonomy and professionalization than the German and Belgian community nurses.

Belgium↗
PubMed1994

Naturally acquired antibodies against the major merozoite surface coat protein (MSP-1) of Plasmodium falciparum acquired by residents in an endemic area of Colombia.

A preliminary baseline epidemiological malaria survey was conducted in the village of Punta Soldado, Colombia. Parasite prevalence and density as well as serological data were obtained from 151 asymptomatic children and adults. Fifty individuals were infected with Plasmodium falciparum. The mean parasite density was 184 parasites/mm3. Greater than 90% of the sample population were P. falciparum antibody positive as detected by the indirect immunofluorescent antibody test (IFAT). The enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies against the major merozoite surface protein (MSP-1) of P. falciparum. In this population, anti-MSP-1 antibody concentration is acquired in an age dependent manner with equal immunogenicity to both the N- and C-terminal regions of the molecule. Infection at the time of sampling was associated with a higher anti-MSP-1 antibody concentration than that found in non-infected individuals. Further studies are planned to assess the role of immune and non-immune factors in limiting the number of cases of severe malaria seen in this population.

Adolescent↗