Biomedical subjects

C M Hansen

Publications and source records attributed to C M Hansen.

At least 19 recordsLinked to original sources

PubMed2002

Activated T lymphocytes disappear from circulation during endotoxemia in humans.

Seventeen volunteers received an intravenous bolus of endotoxin (2 ng/kg of body weight). Endotoxin-induced lymphopenia was constituted mainly by cells with an immature phenotype (CD45RA(+) CD45RO(-)) that were less likely to undergo apoptosis (CD28(+)), whereas cells with the highest rates of disappearance were characterized by an activated phenotype (CD45RA(-) CD45RO(+)) as well as a phenotype linked to apoptosis (CD95(+) CD28(-)). In conclusion, endotoxin-induced lymphopenia reflects the disappearance from the circulation of activated lymphocytes prone to undergo apoptosis.

Adult↗

PubMed2001

Sensitization to TNF-induced apoptosis by 1,25-dihydroxy vitamin D(3) involves up-regulation of the TNF receptor 1 and cathepsin B.

The active form of vitamin D(3), 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), induces caspase-independent apoptosis in MCF-7 and T47D breast cancer cells. Before the appearance of apoptotic cells at Day 4 after the addition of 1,25(OH)(2)D(3), the MCF-7 cells are sensitized to the caspase-mediated apoptosis induced by TNF. We studied the mechanism underlying the cross talk between these 2 distinct death pathways in MCF-7 and T47D cells. Whereas 1,25(OH)(2)D(3) pre-treatment enhanced TNF-induced apoptosis of TNF sensitive MCF-7 cells, it failed to render TNF resistant T47D cells sensitive to this cytokine. Opposing to an earlier report suggesting that cytosolic phospholipase A(2) (cPLA(2)) mediates the 1,25(OH)(2)D(3)-induced sensitization to TNF, we could not detect any cPLA(2) protein in MCF-7 cells and its overexpression had no effect on cellular sensitivity to 1,25(OH)(2)D(3) or the combination with TNF. The sensitization of MCF-7 cells to TNF-induced apoptosis by pre-treatment with 1,25(OH)(2)D(3) may instead be partially explained by an increased surface expression of the TNF receptor 1 (TNF-R1). In line with this, not only the TNF-induced activation of caspases and apoptosis but also that of NF-kappaB was enhanced by 1,25(OH)(2)D(3) pre-treatment. Furthermore, 1,25(OH)(2)D(3) enhanced TNF-induced NF-kappaB activation in T47D cells suggesting that it potentiates TNF signaling in general. Interestingly, the lysosomal protease cathepsin B, which expression is up-regulated by 1,25(OH)(2)D(3), was released from the lysosomes upon TNF treatment, and inhibition of its activity rescued 1,25(OH)(2)D(3) treated MCF-7 cells from TNF-induced apoptosis. In conclusion, 1,25(OH)(2)D(3) may enhance TNF-induced apoptosis by increasing the expression of both the TNF-R1 and cathepsin B.

Antigens, CD↗

PubMed2001

Vitamin D and cancer: effects of 1,25(OH)2D3 and its analogs on growth control and tumorigenesis.

Today, it is well established that besides playing a crucial role in the establishment and maintenance of the calcium homeostasis in the body, the active form of vitamin D, 1,25(OH)2D3, also acts an effective regulator of cell growth and differentiation in a number of different cell types, including cancer cells. This has led to an increased interest in using 1,25(OH)2D3 in the treatment or prevention of cancer patients and to a substantial number of studies investigating the effect of 1,25(OH)2D3 on cancer cells. The results are encouraging, but clearly demonstrate that the therapeutic window of 1,25(OH)2D3 is extremely narrow due to the calcemic adverse effects of this compound. Much effort has consequently been directed into identifying vitamin D analogs with potent cell regulatory effects but with weaker effects on the calcium metabolism than those of 1,25(OH)2D3. In an attempt to clarify the mechanisms implicated in the cell regulatory effects of 1,25(OH)2D3 and eventually facilitate the process of developing new specific vitamin D analogs, numerous investigations have been carried out with 1,25(OH)2D3 and its analogs. The present review will focus on the results obtained in these studies and describe some of the synthetic analogs, which have shown to be of particular interest in relation to cancer.

Animals↗

PubMed2001

MCF-7/VD(R): a new vitamin D resistant cell line.

Several in vitro and in vivo experiments have demonstrated potent cell regulatory effects of vitamin D compounds in cancer cells. Moreover, a promising phase I study with the vitamin D analogue Seocalcitol (EB 1089) in patients with advanced breast and colon cancer has already been carried out and more clinical trials evaluating the clinical effectiveness of EB 1089 in other cancer types are in progress (Mørk Hansen et al. [2000a]). However, only little is known about the mechanisms underlying the actions of vitamin D or about the possible development of drug resistance in the patients. Therefore, in an attempt to gain more insight into these aspects, we have developed the MCF-7/VD(R) cell line, a stable subclone of the human MCF-7 breast cancer cell line, which is resistant to the growth inhibitory and apoptosis inducing effects of 1alpha,25(OH)(2)D(3). Despite this characteristic, receptor studies on the VDR have clearly demonstrated that the MCF-7/VD(R) cells contain fully functional VDRs, although in a lower number than seen with the parental MCF-7 cells. The regulation of the 24-hydroxylase enzyme appeared to be intact in the MCF-7/VD(R) cells and no differences with regard to growth rate and morphological appearance between the MCF-7/VD(R) cells and the parental MCF-7 cells were observed. Interestingly, however, the sensitivity of the MCF-7/VD(R) cells to the pure anti-estrogen ICI 182,780 was found to be increased. The MCF-7/VD(R) cell line shows characteristics different from those of previously described vitamin D resistant breast cancer cell lines but also some similarities. Together such vitamin D resistant cell lines therefore serve as a useful tool for studying the exact mechanism of action of vitamin D and the development of vitamin D resistance.

Adenocarcinoma↗

PubMed2001

Vitamin D compounds exert anti-apoptotic effects in human osteosarcoma cells in vitro.

Several studies have demonstrated that vitamin D regulates growth and differentiation in bone cells in vitro. In addition, in vivo studies have shown that vitamin D stimulates bone formation, increases the number of osteoblast precursor cells and prevents bone mineral loss. These observations indicate that vitamin D may have anabolic effects on bone, and thus therapeutic potential in the treatment of osteoporosis. However, little is known about the effects of vitamin D on apoptosis in bone cells and about the contribution of this process to the effect of vitamin D on bone mineral loss. To investigate this aspect in more detail, we studied the effect of 1alpha,25(OH)(2)D(3) and a series of analogues on apoptosis in human osteosarcoma cells. No significant induction of apoptosis was observed with any of the compounds after a 5 day treatment period. In contrast, some of the analogues showed a tendency to protect the cells from undergoing apoptosis. This anti-apoptotic effect of vitamin D was further confirmed by the ability of 1alpha,25(OH)(2)D(3) to suppress camptothecin- and staurosporin-induced DNA fragmentation in the cells. In cultures treated simultaneously with 1alpha,25(OH)(2)D(3) in combination with camptothecin or staurosporin, the level of DNA fragmentation was markedly reduced compared with cultures treated with camptothecin or staurosporin alone. On the basis of the present results, it is therefore concluded that vitamin D displays anti-apoptotic effects in human osteoblast-like osteosarcoma cells in vitro. This observation suggests that besides regulating growth and differentiation, vitamin D exerts its anabolic effects on bone by protecting osteoblastic cells from undergoing apoptosis.

Apoptosis↗

PubMed2001

Hypotension during endotoxemia in aged humans.

BACKGROUND: and objective The aim of this study was to determine possible age-associated differences in human blood pressure regulation during an immunological challenge in healthy subjects. METHODS: Eight healthy young volunteers (median age 24 yr) and nine healthy elderly volunteers (median age 66 yr) received an intravenous bolus injection of Escherichia coli endotoxin (2 ng kg(-1)). Blood pressure, heart rate and core temperature were monitored during the first 7 h. Plasma catecholamine concentrations were measured at hourly intervals. RESULTS: The elderly showed a significantly more pronounced decrease in mean arterial pressure 4-7 h after endotoxin administration compared with the young controls (ANOVA; age x time; P < 0.0005). This mainly reflected a decrease in the systolic blood pressure in the elderly. The heart rate of both groups increased without difference between groups. Increased plasma epinephrine concentrations were found 2-3 h after endotoxin administration in both groups. Five hours after the endotoxin challenge, the epinephrine concentration had returned to control values in the elderly group only, in spite of decreased blood pressure. CONCLUSION: In conclusion, healthy elderly subjects fail to maintain a constant mean arterial pressure in response to the immunological challenge of endotoxemia.

Adult↗

PubMed2001

Molecular evaluation of vitamin D3 receptor agonists designed for topical treatment of skin diseases.

MC903 (calcipotriol) is a synthetic, low calcemic analog of the nuclear hormone 1alpha,25-dihydroxyvitamin D3 and used in the treatment of psoriasis. The beneficial effects of MC903 on psoriasis are based on gene regulatory events. The genomic actions of 1alpha,25-dihydroxyvitamin D3 and its analogs are primarily mediated by a complex of the vitamin D3 receptor and the retinoid X receptor bound to a 1alpha,25-dihydroxyvitamin D3 response element that can be considered as the molecular switch of 1alpha,25-dihydroxyvitamin D3 signaling. In this study, the interaction of MC903 and two new analogs, GS1500 and EB1213, with this molecular switch was compared with that of 1alpha,25-dihydroxyvitamin D3. In DNA-dependent limited protease digestion assays, ligand-dependent gel shift assays and mammalian-one-hybrid assays, all four ligands appeared to be equally sensitive VDR agonists that activated vitamin D3 receptor-retinoid X receptor-1alpha,25-dihydroxyvitamin D3 response element complexes at a concentration of approximately 0.2 nM. The analyzed VDR agonists, however, also showed individual molecular properties, such as a reduced sensitivity in HaCaT cells (MC903), a selectivity for DNA-bound vitamin D3 receptor-retinoid X receptor heterodimers (GS1500) and a long-lasting stabilization of vitamin D3 receptor-retinoid X receptor-1alpha,25-dihydroxyvitamin D3 response element complexes (EB1213). This molecular evaluation demonstrated that the sensitivity in activating the vitamin D3 receptor is already optimal for MC903, but the analog may not be ideal in keeping the receptor active and in selectively triggering 1alpha,25-dihydroxyvitamin D3 signaling pathways.

Administration, Topical↗

PubMed2001

Stability of vitamin B-6-dependent aminotransferase activity in frozen packed erythrocytes is dependent on storage temperature.

Pyridoxal 5'-phosphate (PLP) stimulation of erythrocyte alanine and aspartate aminotransferase (EALT, EAST) activities is a frequently used functional measure of vitamin B-6 status. Stability of enzyme activities and activity coefficients (AC, stimulated / unstimulated) was assessed in packed erythrocytes frozen at -20, -80 degrees C and under liquid nitrogen (-196 degrees C). Activities of EALT and EAST, with and without added PLP, were determined in fresh erythrocytes (d 0) and frozen samples on d 1, 7, 14, 28, 58 and 84. In -20 degrees C samples, EALT basal activity decreased 17 and 22% (P < or = 0.05 for both) by d 58 and 84, respectively, and EAST basal activity decreased 40% (P < or = 0.05) by d 58. In -80 and -196 degrees C samples, EALT and EAST basal activities did not change significantly. Activity coefficients did not differ significantly from d 0 at any storage temperature, but EAST-AC increased 9-19% (nonsignificant) in samples stored at -20 and -80 degrees C for 7 to 84 d. Additionally, EAST-AC was significantly higher in -20 than -80 and -196 degrees C samples on d 1 and 58, respectively. Erythrocytes may be frozen for 28 d at -20 degrees C and 84 d at -80 degrees C before analysis for EALT; for EAST, activity should be measured on fresh erythrocytes.

Adult↗

PubMed2001

Assessment of vitamin B-6 status in young women consuming a controlled diet containing four levels of vitamin B-6 provides an estimated average requirement and recommended dietary allowance.

The Recommended Dietary Allowance (RDA) of vitamin B-6 for young women was recently reduced from 1.6 to 1.3 mg/d based on an adequate plasma pyridoxal phosphate (PLP) concentration of 20 nmol/L. To assess vitamin B-6 requirements and suggest recommendations for intake, seven healthy young women consumed a controlled diet providing 1.2 g protein/kg body weight for a 7-d adjustment period (1.0 mg vitamin B-6/d) and three successive 14-d experimental periods (1.5, 2.1 and 2.7 mg/d, respectively). Direct and indirect vitamin B-6 status indicators were measured in plasma, erythrocytes and urine. Indicators most strongly correlated with vitamin B-6 intake [i.e., plasma and erythrocyte PLP, urinary 4-pyridoxic acid (4-PA) and total vitamin B-6] were regressed on vitamin B-6 intake and the dietary vitamin B-6 to protein ratio. Inverse prediction using adequate and baseline values estimated vitamin B-6 requirement. Adequate values were determined for plasma PLP and urinary 4-PA from baseline values of 60 previous subjects, using the statistical method suggested by Sauberlich. The current study suggests a vitamin B-6 Estimated Average Requirement (EAR) for young women of 1.1 mg/d or 0.016 mg/g protein, and a RDA of 1.5 mg/d or 0.020 mg/g protein. When results from this study are combined with data from four other recent studies, the combined data predict an EAR of 1.2 mg/d or 0.015 mg/g protein, and a RDA of 1.7 mg/d or 0.018 mg/g protein. This study suggests that the current vitamin B-6 RDA may not be adequate.

Administration, Oral↗

PubMed2001

Ageing is associated with a prolonged fever response in human endotoxemia.

The purpose of this study was to investigate whether an age-associated impaired acute-phase response exists. Nine healthy elderly volunteers (median, 66 years; range, 61 to 69 years) and eight young controls (median, 24 years; range, 20 to 27 years) were given an intravenous bolus of endotoxin (2 ng/kg). The rectal temperature was monitored continuously, and blood samples for cytokine measurements were obtained before endotoxin administration as well as 0.5, 1, 1.5, 2, 3, 4, 8, 12, and 24 h after the injection. The elderly subjects showed a more prolonged fever response compared to the young controls. Levels of tumor necrosis factor alpha (TNF-alpha), soluble TNF receptors (sTNFR-I), interleukin-6 (IL-6), IL-8, IL-10, and IL-1 receptor antagonist (IL-1ra) in plasma increased markedly following endotoxin administration in both groups. The elderly group showed larger initial increases in TNF-alpha and sTNFR-I levels and prolonged increased levels of sTNFR-I. Monocyte concentrations decreased in both groups, with the elderly group showing a more rapid decrease and a slower subsequent increase than did the young group. Furthermore, the elderly group had a more rapid increase in C-reactive protein levels than did the young group. In conclusion, ageing is associated with an altered acute-phase response including initial hyperreactivity, prolonged inflammatory activity, and prolonged fever response.

Acute-Phase Reaction↗

PubMed2000

Expression of a novel factor, com1, is regulated by 1,25-dihydroxyvitamin D3 in breast cancer cells.

Tumor cells and their surrounding microenvironment produce a variety of factors that promote tumor growth and metastasis. We recently identified a nuclear factor, termed com1, that is up-regulated in human breast carcinoma cells on formation of experimental metastatic tumors and is assumed to act as a growth-promoting factor in breast cancer. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] is a potent inhibitor of growth in breast cancer both in vitro and in vivo. We compared the growth-regulatory mechanisms of nontumorigenic and estrogen-dependent MCF-7 cells with those of the tumorigenic and tamoxifen-resistant subline MCF7/ LCC2 in the presence of 1,25(OH)2D3. Proliferation of MCF7/LCC2 cells, which revealed constitutive com1 expression, was inhibited by 1,25(OH)2D3 (10(-7) M). This was strongly associated with cell cycle arrest in G1 phase, consistent with accumulation of the hypophosphorylated form of the retinoblastoma protein as well as the induction of the cyclin-dependent kinase inhibitor p21. These cell cycle events were preceded by a transient up-regulation (5-8-fold) of com1 mRNA. Furthermore, clonal growth of the MCF7/LCC2 cells was also inhibited by 1,25(OH)2D3 (10(-7) M), and when the com1-negative MCF-7 cells were stably transfected with com1, the resulting MCF7/com1 cells showed a significant decrease in colony formation. These results seem to indicate that rather than promoting growth, com1 may participate in the regulatory pathway involved in cellular growth inhibition when recruited by inhibitory signals.

Basic Helix-Loop-Helix Proteins↗

PubMed2000

Seocalcitol (EB 1089): a vitamin D analogue of anti-cancer potential. Background, design, synthesis, pre-clinical and clinical evaluation.

It is well established that the metabolically active form of vitamin D, 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) plays a key role in the establishment and maintenance of the calcium metabolism in the body. In addition to this classic effect of 1alpha,25(OH)2D3, substantial evidence has emerged demonstrating that 1alpha,25(OH)2D3 is able to regulate cell growth and differentiation in a number of different cell types, including cancer cells. However, the clinical usefulness of 1alpha,25(OH)2D3 is limited by its tendency to cause hypercalcaemia. Much effort has therefore been directed to identifying new vitamin D analogues with potent cell regulatory effects, but with weaker effects on the calcium metabolism than those of 1alpha,25(OH)2D3. One of these new synthetic analogues is Seocalcitol (EB 1089). Despite being 50-200 times more potent than 1alpha,25(OH)2D3 with respect to regulation of cell growth and differentiation in vitro as well as in vivo, EB 1089 displays a reduced calcaemic activity in vivo compared to that of 1alpha, 25(OH)2D3. These characteristics make EB 1089 a potentially useful compound for the treatment of cancer. Recent clinical evaluation of EB 1089 has focused mainly on establishing a maximum tolerated dose in cancer patients. Early results confirm that the low calcaemic activity observed in animals can be reproduced in the clinic. Furthermore, EB 1089 has been shown to induce regression of tumours, especially in hepatocellular carcinoma where complete remission has been obtained. In conclusion, the development of EB 1089 as an anti-cancer drug holds promise. However, its final evaluation must await the completion of ongoing controlled clinical trials.

Animals↗

PubMed1999

Application of the bootstrap procedure provides an alternative to standard statistical procedures in the estimation of the vitamin B-6 requirement.

The bootstrap procedure is a versatile statistical tool for the estimation of standard errors and confidence intervals. It is useful when standard statistical methods are not available or are poorly behaved, e.g., for nonlinear functions or when assumptions of a statistical model have been violated. Inverse regression estimation is an example of a statistical tool with a wide application in human nutrition. In a recent study, inverse regression was used to estimate the vitamin B-6 requirement of young women. In the present statistical application, both standard statistical methods and the bootstrap technique were used to estimate the mean vitamin B-6 requirement, standard errors and 95% confidence intervals for the mean. The bootstrap procedure produced standard error estimates and confidence intervals that were similar to those calculated by using standard statistical estimators. In a Monte Carlo simulation exploring the behavior of the inverse regression estimators, bootstrap standard errors were found to be nearly unbiased, even when the basic assumptions of the regression model were violated. On the other hand, the standard asymptotic estimator was found to behave well when the assumptions of the regression model were met, but behaved poorly when the assumptions were violated. In human metabolic studies, which are often restricted to small sample sizes, or when statistical methods are not available or are poorly behaved, bootstrap estimates for calculating standard errors and confidence intervals may be preferred. Investigators in human nutrition may find that the bootstrap procedure is superior to standard statistical procedures in cases similar to the examples presented in this paper.

Adult↗

PubMed1998

Structural variants of the vitamin D analogue EB1089 reduce its ligand sensitivity and promoter selectivity.

The nuclear hormone 1alpha,25-dihydroxyvitamin D3 (VD) has important cell-regulatory functions but also a strong calcemic effect. Therefore, various VD analogues have been synthesized and screened for their biological profile. In order to gain more insight into the molecular basis of the high antiproliferative but low calcemic action of the VD analogue EB1089, we characterized this compound in comparison to five structurally related VD analogues. The activities of the six VD analogues in in vitro assays (limited protease digestion assays for determining interaction with monomeric vitamin D receptor (VDR), ligand-dependent gel shift assays for showing the increase of DNA binding of VDR-retinoid X receptor (RXR) heterodimers, and reporter gene assays on different types of VD response elements for demonstrating the efficacy in nuclear VD signalling) were found to represent their biological potency (antiproliferative effect on different malignant cell lines). In this series, EB1089 proved to be the most potent VD analogue; that is, every structural modification (20-epi configuration, cis-configuration at position C24, or changes at the ethyl groups at position C25) appeared to reduce the determined activities mediated through the VDR of these analogues. Moreover, the modifications of EB1089 resulted in a loss of VD response element selectivity, suggesting that this parameter is very critical for the biological profile of this VD analogue.

Calcitriol↗

PubMed1998

[Severely traumatized patients admitted to Aarhus Community Hospital 1994-1995].

In Denmark, only few studies have addressed the problem of severe trauma. In relation to establishing a trauma manual at our hospital we studied trauma patients requiring immediate anaesthesiological assistance. Patients from the preceeding years, 1994-1995 were identified. The injuries were scored according to the Abbreviated Injury Scale (AIS), and Injury Severity Scores (ISS) were calculated. Two hundred and fifty-eight trauma patients were identified, 132 of these were severely injured, defined as having ISS > or = 15. Of these, 75 patients were multitraumatised, defined as AIS > or = 3 in at least two regions. None of the patients with ISS < or = 15 died. Mortality was 49% among severely injured but not multitraumatised patients, while mortality was 56% among the multitraumatised patients. Head injuries were the most frequently found severe injury (AIS > or = 3), followed by injuries to the thorax and extremities. The anaesthesiologist and the orthopaedic surgeon were involved in initial diagnosis and treatment in all patients, and beyond these a variety of medical specialties were involved. In the light of this study we have revised our procedures and registration concerning severe trauma patients.

Adolescent↗

PubMed1998

Studies on the interaction between the vitamin D receptor and the radiolabelled 20-epi vitamin D analogue GS 1500.

Previous studies have shown that the binding affinity of a vitamin D analogue for the vitamin D receptor (VDR) does not correlate with the biological potency of the compound. In the present investigation the vitamin D analogue GS 1500, which is characterised by an altered stereochemistry at carbon C-20 (20-epi) and an aromatic ring in the side chain, was studied with respect to its interaction with the VDR. Using [3H]-GS 1500 as tracer, the receptor binding properties of GS 1500 were investigated and compared to those of 1,25(OH)2D3. The binding studies did not reveal a different binding site for GS 1500 than the one already established, and the binding affinity was in accordance with previously found values. At the level of VDR interaction with the vitamin D responsive element, GS 1500 did induce a binding complex at a lower concentration than 1,25(OH)2D3, which may help explain the difference in potency.

Animals↗

PubMed1998

Sequence analysis of porcine reproductive and respiratory syndrome virus of the American type collected from Danish swine herds.

Vaccine-like viruses of American type of porcine reproductive and respiratory syndrome virus (PRRSV) were detected in serum samples by RT-PCR. The viruses were analysed by nucleotide sequencing of the genomic region encoding open reading frames 2 to 7. During the ongoing study of Danish isolates of PRRSV by means of nucleotide sequencing, RT-PCR reactions and subsequent nucleotide sequencing showed the presence of American type PRRSV in Danish breeding herds. Most likely, these atypical viruses originated from boars vaccinated with live vaccine of American type (MLV RespPRRS), which were taken to artificial insemination centres and there brought together with unvaccinated boars already at the centres. The nucleotide sequences of three Danish viruses of American type PRRSV were compared to those of known PRRSV isolates. The nucleotide sequence identities of the atypical Danish isolates were between 99.2-99.5% to the vaccine virus RespPRRS and 99.0-99.3% to VR2332 which are the parental virus to the vaccine virus. Phylogenetic analysis including field isolates of American type supports the conclusion that the introduction of American type PRRSV in Denmark was due to spread of vaccine virus.

Amino Acid Sequence↗

PubMed1998

New 1 alpha,25-dihydroxy vitamin D3 analogues with side chains attached to C-18: synthesis and biological activity.

A new class of analogues of 1 alpha,25-dihydroxy vitamin D3 has been synthesised, in which the side chain (C-23 to C-27) has been removed and where new hydroxylated side chains have been attached to the C-18 methyl group. These analogues show antiproliferative activity in U937 and HaCaT cells comparable to that of 1 alpha,25-dihydroxy vitamin D3. Lack of calcemic activity makes these analogues potentially useful in the treatment of proliferative diseases.

Animals↗