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Biomedical subjects

E de Vries

Publications and source records attributed to E de Vries.

At least 55 records · Page 3Linked to original sources
PubMed2000

Neonatal blood lymphocyte subpopulations: a different perspective when using absolute counts.

We compared the absolute counts of lymphocyte subpopulations in 15 neonates, and 9 adults using the whole lysed blood technique with 15 different triple immunostainings. To obtain accurate absolute lymphocyte counts in neonatal cord blood samples, the flow cytometric 'lympho-gate' was corrected for the erythroid cell contamination by normoblasts and unlysed erythrocytes. In contrast to earlier studies where relative frequencies were reported, we found that the major difference between neonatal and adult lymphocyte subpopulations concerned the much larger pool of naive 'untriggered' cells in neonates, standby for participation in primary immune responses.

Adult↗
PubMed2000

Longitudinal survey of lymphocyte subpopulations in the first year of life.

Age-matched reference values for lymphocyte subpopulations are generally obtained via cross-sectional studies, whereas patients are followed longitudinally. We performed a detailed longitudinal analysis of the changes in lymphocyte subpopulations in a group of 11 healthy infants followed from birth up to 1 y of age, with special attention for early developmental markers, markers of maturation, and markers of activation. We found that T and B lymphocytes increased at 1 and 6 wk of age, respectively. In contrast, NK cells showed a sharp decline directly after birth, suggesting that they are more important during pregnancy than thereafter. CD45RA+--mainly CD4+--naive T lymphocytes were high at birth, and increased further during the first year of life; they form a large expanding pool of cells, ready for participation in primary immune responses. The absolute counts of CD45RO+ memory T lymphocytes were similar in infants and adults, albeit with a lower level of expression of CD45RO on infant T lymphocytes. Almost all infant T lymphocytes expressed CD38 throughout the first year of life. The abundant expression of CD38 on an infant's T lymphocytes might be related to a greater metabolic need of the large population of naive untriggered cells that are continually involved in primary immune responses during the first year of life. The high B lymphocyte counts in infants mainly concerned CD38+ B lymphocytes throughout the first year of life. Also, the relative frequencies of CD1c+ and CD5+ B lymphocytes were higher throughout the first year of life than in adults. Therefore, CD1c, CD5, and CD38 could be markers of untriggered B lymphocytes. In conclusion, our longitudinal survey of T and B lymphocytes, NK cells, and their subpopulations during the first year of life helps to complete the picture of lymphocyte development in infants. This information contributes to the correct interpretation of data from infants with possible immune disorders.

Antigens, CD↗
PubMed1999

Common regulation of apoptosis signaling induced by CD95 and the DNA-damaging stimuli etoposide and gamma-radiation downstream from caspase-8 activation.

The death receptor CD95 (APO-1/Fas), the anticancer drug etoposide, and gamma-radiation induce apoptosis in the human T cell line Jurkat. Variant clones selected for resistance to CD95-induced apoptosis proved cross-resistant to etoposide- and radiation-induced apoptosis, suggesting that the apoptosis pathways induced by these distinct stimuli have critical component(s) in common. The pathways do not converge at the level of CD95 ligation or caspase-8 signaling. Whereas caspase-8 function was required for CD95-mediated cytochrome c release, effector caspase activation, and apoptosis, these responses were unaffected in etoposide-treated and irradiated cells when caspase-8 was inhibited by FLIPL. Both effector caspase processing and cytochrome c release were inhibited in the resistant variant cells as well as in Bcl-2 transfectants, suggesting that, in Jurkat cells, the apoptosis signaling pathways activated by CD95, etoposide, and gamma-radiation are under common mitochondrial control. All three stimuli induced ceramide production in wild-type cells, but not in resistant variant cells. Exogenous ceramide bypassed apoptosis resistance in the variant cells, but not in Bcl-2-transfected cells, suggesting that apoptosis signaling induced by CD95, etoposide, and gamma-radiation is subject to common regulation at a level different from that targeted by Bcl-2.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Expression of Fas and Fas ligand in cutaneous B-cell lymphomas.

Primary cutaneous B-cell lymphomas (CBCLs) represent a rare, but distinct group of B-cell neoplasms with a different clinical behaviour to B-cell lymphomas secondarily involving the skin. Fas-Fas ligand (Fasl) expression was investigated in a group of primary and secondary CBCLs to gain an insight into the putative role of these apoptotic molecules in the clinical behaviour of these lymphomas. Frozen and paraffin sections from 32 patients with a CBCL were investigated for Fas and Fasl expression, using immunohistochemistry. This group included 24 primary CBCLs [14 primary cutaneous follicle centre cell lymphomas (PCFCCLs), six primary cutaneous large B-cell lymphomas (PCLBCLs) on the leg, and four primary cutaneous immunocytomas] and eight secondary CBCLs. The results were correlated with follow-up data, bcl-2, and ICAM-1 expression. High Fas expression and absent or low Fasl expression were detected in the vast majority of PCFCCLs and immunocytomas. The group of PCLBCLs on the leg, which have an intermediate prognosis, showed variable results with relatively higher Fasl expression. The highest Fasl expression was found in the more aggressive secondary CBCLs whereas in this group, Fas was undetectable in five of eight cases. Statistical analysis showed that Fas and ICAM-1 expression was strongly related to a favourable prognosis, whereas expression of Fasl and bcl-2 was related to a very poor prognosis. Although only type of CBCL and age, but not Fas, Fasl, bcl-2, and ICAM-1 expression, proved independent prognostic parameters using multivariate analysis, the results of this study suggest that differences in the expression of Fas and Fasl, as well as bcl-2 and ICAM-1, contribute to the differences in clinical behaviour between these different types of CBCL.

Adult↗
PubMed1999

Analysing the developing lymphocyte system of neonates and infants.

UNLABELLED: Technical developments in immunophenotyping and function testing have greatly facilitated studies on the developing lymphocyte system in the past decade and contributed to a better interpretation of the data obtained in these studies. This is important for the correct interpretation of data obtained in paediatric patients with possible immunological diseases. The age-related differences in lymphocyte subpopulations and function imply that the available adult reference values cannot be used in children. CONCLUSION: In this review we give an outline of the technical developments, their influence upon the interpretation of data, and the available literature about age-related changes in the developing lymphocyte system.

Humans↗
PubMed1999

Inhibition of the in vitro growth of Plasmodium falciparum by acyclic nucleoside phosphonates.

Forty-eight acyclic nucleoside phosphonates (putative prodrugs of acyclic nucleoside triphosphate inhibitors of DNA replication) have been evaluated for in vitro antiplasmodial activity. Only certain purine derivatives with a hydroxyl group attached to the acyclic sugar moiety displayed antiplasmodial activity. The two most active analogs were (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine ((S)-HPMPA, IC50=0.18+/-0.07 microM) and (S)-3-deaza-HPMPA (IC50=0.29+/-0.08 microM). Their cyclic derivatives, containing an ester bond between the phosphonate and the hydroxyl group, were slightly less active. All tested compounds that lacked the hydroxyl group, including potent antiretrovirus analogs such as 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and the (S)-HPMPA derivatives (R)-PMPA and (S)-FPMPA, did not show any activity, even at very high concentrations ( >250 microM). Similarly, pyrimidine analogs of (S)-HPMPA, such as (S)-HPMPT, (S)-HPMPU and the anti-herpesvirus analog (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl) cytosine ((S)-HPMPC), were devoid of any antiplasmodial activity. In addition, 11 acyclic nucleoside (non-phosphorylated) analogs--which in contrast to the acyclic nucleoside phosphonates require the presence of a monophosphorylating enzyme for the first activation step--were tested. None of them inhibited the growth of the parasite. In short three chemical entities seem to be imperative for antiplasmodial activity: a purine base, a hydroxyl group in the acyclic side chain and a phosphonate group terminating this chain.

Adenine↗
PubMed1999

Simultaneous detection of bovine Theileria and Babesia species by reverse line blot hybridization.

A reverse line blot (RLB) assay was developed for the identification of cattle carrying different species of Theileria and Babesia simultaneously. We included Theileria annulata, T. parva, T. mutans, T. taurotragi, and T. velifera in the assay, as well as parasites belonging to the T. sergenti-T. buffeli-T. orientalis group. The Babesia species included were Babesia bovis, B. bigemina, and B. divergens. The assay employs one set of primers for specific amplification of the rRNA gene V4 hypervariable regions of all Theileria and Babesia species. PCR products obtained from blood samples were hybridized to a membrane onto which nine species-specific oligonucleotides were covalently linked. Cross-reactions were not observed between any of the tested species. No DNA sequences from Bos taurus or other hemoparasites (Trypanosoma species, Cowdria ruminantium, Anaplasma marginale, and Ehrlichia species) were amplified. The sensitivity of the assay was determined at 0.000001% parasitemia, enabling detection of the carrier state of most parasites. Mixed DNAs from five different parasites were correctly identified. Moreover, blood samples from cattle experimentally infected with two different parasites reacted only with the corresponding species-specific oligonucleotides. Finally, RLB was used to screen blood samples collected from carrier cattle in two regions of Spain. T. annulata, T. orientalis, and B. bigemina were identified in these samples. In conclusion, the RLB is a versatile technique for simultaneous detection of all bovine tick-borne protozoan parasites. We recommend its use for integrated epidemiological monitoring of tick-borne disease, since RLB can also be used for screening ticks and can easily be expanded to include additional hemoparasite species.

Animals↗
PubMed1999

Correction for erythroid cell contamination in microassay for immunophenotyping of neonatal lymphocytes.

Immunophenotyping of blood lymphocyte subpopulations in neonates and young infants is hampered by the limited amount of blood that can be collected. Contamination of the flow cytometric "lympho-gate" by normoblasts and analysed erythrocytes, and therefore the underestimation of the relative frequencies of lymphocyte subpopulations, interferes with the precise calculation of absolute counts. A microassay was developed by adapting the lysed whole blood technique. Triple immunostaining in a single antibody staining step was used to reduce washing steps and cell loss. Introduction of a triple staining for CD71 (expressed by erythroid precursors), glycophorin A (GpA, expressed by all erythroid cells), and CD45 (expressed by all leucocytes) permitted the relative frequencies of normoblasts (CD71(+)/GpA+/CD45(-) population) and unlysed erythrocytes (CD71(-)/GpA+/CD45(-) population)to be identified and measured within the "lympho-gate" of neonatal cord blood samples. Particularly high frequencies were found (median: 31%) in cord blood samples from preterm neonates. These erythroid cells disappear rapidly by 1 week of age The relative frequencies of erythroid cells can be used to calculate correct lymphocyte subpopulation values. Using only 0.5-0.8 ml of blood, this micro- assay would also be suitable for rapid prenatal immunodiagnosis of congenital immunodeficiencies.

Antigens, CD↗
PubMed1999

Ordering of ceramide formation, caspase activation, and mitochondrial changes during CD95- and DNA damage-induced apoptosis.

To evaluate the role of ceramide (Cer) in apoptosis signaling, we examined Cer formation induced by CD95, etoposide, or gamma-radiation (IR) in relation to caspase activation and mitochondrial changes in Jurkat T cells. The Cer response to all three stimuli was mapped in between caspases sensitive to benzoyloxycarbonyl-VAD-fluoromethylketone (zVAD-fmk) and acetyl-DEVD-aldehyde (DEVD-CHO). Cer production was independent of nuclear fragmentation but associated with the occurrence of other aspects of the apoptotic morphology. Caspase-8 inhibition abrogated Cer formation and apoptosis induced by CD95 but did not affect the response to etoposide or IR, placing CD95-induced Cer formation downstream from caspase-8 and excluding a role for caspase-8 in the DNA damage pathways. CD95 signaling to the mitochondria required caspase-8, whereas cytochrome c release in response to DNA damage was caspase-independent. These results indicate that the caspases required for the Cer response to etoposide and IR reside at or downstream from the mitochondria. Bcl-2 overexpression abrogated the Cer response to etoposide and IR and reduced CD95-induced Cer accumulation. We conclude that the Cer response to DNA damage fully depends on mitochondrion-dependent caspases, whereas the response to CD95 partially relies on these caspases. Our data imply that Cer is not instrumental in the activation of inducer caspases or signaling to the mitochondria. Rather, Cer formation is associated with the execution phase of apoptosis.

Amino Acid Chloromethyl Ketones↗
PubMed1998

CD95 (Fas/APO-1) induces ceramide formation and apoptosis in the absence of a functional acid sphingomyelinase.

CD95 is a potent inducer of apoptosis. It activates the caspase cascade, but also induces ceramide (Cer) production, reportedly involving acid sphingomyelinase (aSMase) activity. A role for Cer as a second messenger for apoptosis induction was proposed, based on the finding that synthetic Cer analogues can induce cell death. We have tested whether aSMase is required for 1) apoptosis induction and 2) Cer production by CD95. For this purpose, we have used cultured Niemann-Pick disease (NPD) lymphoid cells with a defined mutation (R600H) in the aSMase protein. Despite their inherited deficiency of aSMase, we found that these cells readily undergo apoptosis upon CD95 stimulation. After retrovirus-mediated gene transfer of the aSMase cDNA, the transduced (i.e. "corrected") NPD cells showed neither increased levels of apoptosis nor altered kinetics of caspase-8 and caspase-3 activation and apoptosis induction as compared with empty vector-transduced cells. The slow sustained elevation of Cer levels in response to CD95, which we have previously documented for Jurkat T cells (Tepper, A. D., Boesen-de Cock, J. G. R., de Vries, E., Borst, J., and van Blitterswijk, W. J. (1997) J. Biol. Chem. 272, 24308-24312), was similarly found in NPD cells. Moreover, the kinetics of Cer formation remained unaffected after aSMase transduction. These results indicate that this Cer does not result from aSMase activity. We conclude that aSMase is not required for and does not facilitate CD95-mediated apoptosis and that it is not responsible for the late Cer response.

Apoptosis↗
PubMed1998

pUCPCR1. A vector for direct cloning of PCR products in a double Xcm1 restriction site offering compatible single 3'-overhanging T residues.

The multiple cloning site of pUC19 was replaced by a multiple cloning site possessing a double Xcm1 restriction site. Digestion with XcmI gives a linear vector with a single 3'-overhanging T-residue at both ends. This provides the easiest way of creating a vector in which PCR fragments produced by Taq polymerase can be directly cloned without further modifications.

Base Sequence↗
PubMed1998

The anti-cancer drug etoposide can induce caspase-8 processing and apoptosis in the absence of CD95 receptor-ligand interaction.

Caspase-8 (FLICE) can associate with and be activated by CD95 (APO-1/Fas), an apoptosis-inducing member of the Tumour Necrosis Factor receptor family. We find that, in Jurkat T cells, the DNA damaging anti-cancer drug etoposide induces apoptosis and, surprisingly, processing of caspase-8. Therefore, we have investigated whether etoposide involves CD95 receptor activation. We find that etoposide does not induce CD95 ligand expression at the mRNA level. In addition, blocking of CD95 receptor function with a specific antibody does not inhibit etoposide-induced apoptosis. Apparently, in Jurkat cells, etoposide can induce caspase-8 processing and apoptosis in a CD95-independent fashion. Likewise, we find that thymocytes from the CD95-deficient lpr/lpr mouse strain readily undergo apoptosis in response to etoposide. Moreover, since inhibition of the secretory pathway with brefeldin A does not inhibit etoposide-induced apoptosis, we exclude the requirement for a newly synthesized receptor ligand to induce the apoptotic pathway. We conclude that, at least in certain cell types, etoposide does not require CD95 receptor function to induce caspase-8 processing and apoptosis.

Journal Article↗
PubMed1998

Identification of multiple mRNA and DNA sequences from small tissue samples isolated by laser-assisted microdissection.

Molecular analysis of small tissue samples has become increasingly important in biomedical studies. Using a laser dissection microscope and modified nucleic acid isolation protocols, we demonstrate that multiple mRNA as well as DNA sequences can be identified from a single-cell sample. In addition, we show that the specificity of procurement of tissue samples is not compromised by smear contamination resulting from scraping of the microtome knife during sectioning of lesions. The procedures described herein thus allow for efficient RT-PCR or PCR analysis of multiple nucleic acid sequences from small tissue samples obtained by laser-assisted microdissection.

Base Sequence↗
PubMed1997

CD95/Fas-induced ceramide formation proceeds with slow kinetics and is not blocked by caspase-3/CPP32 inhibition.

The current confusion regarding the relevance of endogenous ceramide in mediating CD95/Fas-induced apoptosis is based mainly on (i) discrepancies in kinetics of the ceramide response between different studies using the same apoptotic stimulus and (ii) the observation that late ceramide formation (hours) often parallels apoptosis onset. We investigated CD95-induced ceramide formation in Jurkat cells, using two methods (radiolabeling/thin layer chromatography and benzoylation/high performance liquid chromatography), which, unlike the commonly used diglyceride kinase assay, discriminate between ceramide species and de novo formed dihydroceramide. We demonstrate that ceramide accumulates after several hours, reaching a 7-fold increase after 8 h, kinetics closely paralleling apoptosis induction. No fast response was observed, not even in the presence of inhibitors of ceramide metabolism. The majority ( approximately 70%) of the ceramide response remained unaffected when apoptosis was completely inhibited at the level of caspase-3/CPP32 processing by the inhibitor peptide DEVD-CHO. Exogenous cell-permeable C2-ceramide induced the proteolytic processing of caspase-3, albeit with somewhat slower kinetics than with CD95. DEVD-CHO dose-dependently inhibited C2-ceramide- or exogenous sphingomyelinase-induced apoptosis. The results support the idea that ceramide acts in conjunction with the caspase cascade in CD95-induced apoptosis.

Apoptosis↗
PubMed1997

A dendritic-cell-derived C-C chemokine that preferentially attracts naive T cells.

Dendritic cells form a system of highly efficient antigen-presenting cells. After capturing antigen in the periphery, they migrate to lymphoid organs where they present the antigen to T cells. Their seemingly unique ability to interact with and sensitize naive T cells gives dendritic cells a central role in the initiation of immune responses and allows them to be used in therapeutic strategies against cancer, viral infection and other diseases. How they interact preferentially with naive rather than activated T lymphocytes is still poorly understood. Chemokines direct the transport of white blood cells in immune surveillance. Here we report the identification and characterization of a C-C chemokine (DC-CK1) that is specifically expressed by human dendritic cells at high levels. Tissue distribution analysis demonstrates that dendritic cells present in germinal centres and T-cell areas of secondary lymphoid organs express this chemokine. We show that DC-CK1, in contrast to RANTES, MIP-1alpha and interleukin-8, preferentially attracts naive T cells (CD45RA+). The specific expression of DC-CK1 by dendritic cells at the site of initiation of an immune response, combined with its chemotactic activity for naive T cells, suggests that DC-CK1 has an important rule in the induction of immune responses.

Amino Acid Sequence↗