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N M Hjelm

Publications and source records attributed to N M Hjelm.

At least 37 records · Page 2Linked to original sources
PubMed2000

Plasma DNA as a prognostic marker in trauma patients.

BACKGROUND: Recently, much interest has developed in the potential use of plasma DNA as a diagnostic and monitoring tool. We hypothesized that plasma DNA is increased in patients with trauma and may be prognostic in such patients. METHODS: We studied 84 patients who had sustained an acute blunt traumatic injury. We measured plasma DNA by a real-time quantitative PCR assay for the beta-globin gene. Blood samples were collected at a median time of 60 min following injury. Blood samples were also obtained from 27 control subjects. RESULTS: The median plasma DNA concentrations in the control, minor/moderate trauma (Injury Severity Score <16; n = 47), and major trauma (Injury Severity Score > or =16; n = 37) groups were 3154 kilogenome-equivalents/L, 13 818 kilogenome-equivalents/L, and 181 303 kilogenome-equivalents/L, respectively. Plasma DNA concentrations in patients with adverse outcomes, including acute lung injury, acute respiratory distress syndrome, and death, had 11. 6- to 12-fold higher plasma DNA concentrations than those who did not develop these complications. At a cutoff of 232 719 kilogenome-equivalents/L, the sensitivities of plasma DNA analysis for the prediction of acute lung injury, acute respiratory distress syndrome, and death were 100% (95% confidence interval, 100-100%), 100% (95% confidence interval, 100-100%), and 78% (95% confidence interval, 40-97%), respectively. The respective specificities were 81% (95% confidence interval, 71-89%), 80% (95% confidence interval, 70-88%), and 82% (95% confidence interval, 71-90%). CONCLUSIONS: Plasma DNA is increased after trauma and may be a potentially valuable prognostic marker for these patients.

Biomarkers↗
PubMed1999

Quantitative and temporal correlation between circulating cell-free Epstein-Barr virus DNA and tumor recurrence in nasopharyngeal carcinoma.

Recently, cell-free EBV DNA has been detected in the plasma and serum of patients with nasopharyngeal carcinoma (NPC). We studied the relationship between plasma/serum EBV DNA and tumor recurrence. Using real-time quantitative PCR, the median plasma EBV DNA concentration in 10 patients with tumor recurrence was determined to be 32,350 copies/ml, whereas that in 15 patients in continuous remission for a mean period of 2 years was 0 copy/ml. Longitudinal follow-up of 17 NPC patients revealed 6 individuals with tumor recurrence and 11 patients who remained in remission. Significant elevations in serum EBV DNA, sometimes up to 6 months before detectable clinical deterioration, were observed in the patients who subsequently developed tumor recurrence. Continuously low or undetectable levels of serum EBV DNA were observed in the patients who remained in remission. These results suggest that plasma/serum cell-free EBV DNA may be a valuable tool for the monitoring of NPC patients for the early detection of tumor recurrence.

Bone Neoplasms↗
PubMed1999

Quantitative analysis of aberrant p16 methylation using real-time quantitative methylation-specific polymerase chain reaction.

We have developed a quantitative method for methylation analysis of the p16 gene based on real-time methylation-specific PCR (MSP). Real-time MSP is sensitive enough to detect down to 10 genome equivalents of the methylated p16 sequence. Application of real-time MSP to DNA from tumor-derived cell lines revealed complete concordance with conventional MSP analysis. Quantitative data generated by real-time MSP were expressed as the methylation index, which was defined as the percentage of bisulfite-converted DNA that consisted of methylated target sequences. The methylation index was shown to be inversely correlated with p16 gene transcription during demethylation treatment of cell lines with 5-aza-2'-deoxycytidine. The application of real-time MSP to bone marrow aspirates from patients with multiple myeloma revealed complete concordance with conventional MSP analysis. Real-time quantitative MSP may have applications in elucidating diverse biological processes involving DNA methylation and may become a valuable diagnostic tool for detecting tumor-associated epigenetic changes in cancer patients.

DNA Methylation↗
PubMed1999

Differentiation of a human eosinophilic leukemic cell line, EoL-1: characterization by the expression of cytokine receptors, adhesion molecules, CD95 and eosinophilic cationic protein (ECP).

Purification of enough eosinophils for the study of allergic inflammation is difficult because eosinophils comprise only a small percentage of circulating leucocytes. A human eosinophilic leukemic cell line, EoL-1, has been considered to be an in vitro eosinophilic model. In the present study, the suitability of EoL-1 cells as an eosinophilic model was further investigated. EoL-1 cells were induced to differentiate by dibutyryl cyclic AMP (dbcAMP). The expression of cell surface cytokines (IL-3, IL-5, GM-CSF) receptors, adhesion molecules (CD49d, CD11b), and CD95 (Fas) was investigated by flow cytometry. Expression of eosinophilic cationic protein (ECP) was determined by fluorescence enzyme immunoassay (FEIA) and reverse transcription-polymerase chain reaction (RT-PCR). EoL-1 cells could be differentiated into eosinophilic vacuole-containing cells by dbcAMP. They were found to express cell surface IL-3 and GM-CSF receptors, CD95 and CD49d. Treatment with dbcAMP could induce the expression of CD11b but decrease the expression of CD95. Anti-CD95 antibody could induce their apoptosis. The differentiation of EoL-1 cells was accompanied by increase in release of ECP into the supernatant and total ECP synthesis. Differentiation of EoL-1 cells also up-regulated the expression of mRNA for ECP and its level was parallel to the total amount of ECP synthesis. By virtue of their expression of haematopoietic cytokines receptors, adhesion molecules, CD95, synthesis and release of ECP, EoL-1 cells are suitable as an in vitro eosinophilic model for studying eosinophilic functions.

Antigens, CD↗
PubMed1999

Quantitative analysis of cell-free Epstein-Barr virus DNA in plasma of patients with nasopharyngeal carcinoma.

Using real-time quantitative PCR, cell-free EBV DNA was detectable in the plasma of 96% (55 of 57) of nasopharyngeal carcinoma (NPC) patients (median concentration, 21058 copies/ml) and 7% (3 of 43) of controls (median concentration, 0 copies/ml). Advanced-stage NPC patients had higher plasma EBV DNA levels than those with early-stage disease. At 1 month after completion of radiotherapy, plasma EBV DNA was undetectable in 7 of 15 subjects (47%) but remained high in the remaining 8 subjects (53%). Clinical examination revealed that all of the former seven subjects had complete tumor regression, whereas six of the eight latter subjects exhibited evidence of disease persistence or had developed distant metastases. These results suggest that quantitative analysis of plasma EBV DNA may be a useful clinical and research tool in the screening and monitoring of NPC patients.

DNA, Viral↗
PubMed1999

Detection of aberrant p16 methylation in the plasma and serum of liver cancer patients.

We have studied the feasibility of detecting tumor-associated aberrant p16 methylation in the circulation of patients with hepatocellular carcinoma (HCC). We extracted DNA from the tumor tissues and peripheral blood plasma or serum of 22 HCC patients. p16 methylation was found in 73% (16 of 22) of HCC tissues using methylation-specific PCR. Among the 16 cases with aberrant methylation in the tumor tissues, similar changes were also detected in the plasma/serum samples of 81% (13 of 16) of the cases. No methylated p16 sequences were detected in the peripheral plasma/serum of the six HCC cases without these changes in the tumor, in 38 patients with chronic hepatitis/cirrhosis, or in 10 healthy control subjects. These results suggest that circulating liver tumor DNA may be detected using tumor-associated DNA methylation changes. Because methylation abnormalities have been found in many other genes and tumor types, this approach may have implications for the noninvasive detection of a wide variety of cancers.

Adult↗
PubMed1999

Glycan composition of serum alpha-fetoprotein in patients with hepatocellular carcinoma and non-seminomatous germ cell tumour.

Although estimation of serum alpha-fetoprotein (AFP) is widely used in the diagnosis of hepatocellular carcinoma (HCC) and non-seminomatous germ cell tumours (NSGCT), the clinical usefulness of this test is limited by a low specificity. However, there exist glycoforms of AFP which may be more specific for particular tumours. Previously, detailed analysis has been prevented by the low levels of AFP in human serum. We report here the application of fluorescence labelling, sequential exoglycosidase digestion, high-performance liquid chromatography and matrix-assisted laser desorption ionization in time-of-flight mass spectrometry, to determine the glycan structures of purified serum AFP from patients with HCC and NSGCT. Eleven major glycans were found, of which seven were N-linked, and four were O-linked, to the protein backbone. The structure of the N-linked glycans (all of bi-antennary complex-type with varying degrees of sialylation, fucosylation and galactosylation) were consistent with those previously reported. The O-linked glycans (three mucin O-GalNAc type glycans with variable degrees of sialylation, one O-HexNAc monosaccharide glycan) have not previously been reported. The finding of mucin O-GalNAc type glycans was supported by the prediction of potential O-GalNAc glycosylation sites on the protein backbone by analysis of the AFP structure by molecular modelling. With knowledge of these structures it may be possible to develop more specific assays for the detection of HCC and NSGCT.

Amino Acid Sequence↗
PubMed1999

Rapid clearance of fetal DNA from maternal plasma.

Fetal DNA has been detected in maternal plasma during pregnancy. We investigated the clearance of circulating fetal DNA after delivery, using quantitative PCR analysis of the sex-determining region Y gene as a marker for male fetuses. We analyzed plasma samples from 12 women 1-42 d after delivery of male babies and found that circulating fetal DNA was undetectable by day 1 after delivery. To obtain a higher time-resolution picture of fetal DNA clearance, we performed serial sampling of eight women, which indicated that most women (seven) had undetectable levels of circulating fetal DNA by 2 h postpartum. The mean half-life for circulating fetal DNA was 16.3 min (range 4-30 min). Plasma nucleases were found to account for only part of the clearance of plasma fetal DNA. The rapid turnover of circulating DNA suggests that plasma DNA analysis may be less susceptible to false-positive results, which result from carryover from previous pregnancies, than is the detection of fetal cells in maternal blood; also, rapid turnover may be useful for the monitoring of feto-maternal events with rapid dynamics. These results also may have implications for the study of other types of nonhost DNA in plasma, such as circulating tumor-derived and graft-derived DNA in oncology and transplant patients, respectively.

DNA↗
PubMed1999

Mutations of OCTN2, an organic cation/carnitine transporter, lead to deficient cellular carnitine uptake in primary carnitine deficiency.

Systemic primary carnitine deficiency (CDSP, OMIM 212140) is an autosomal recessive disease characterized by low serum and intracellular concentrations of carnitine. CDSP may present with acute metabolic derangement simulating Reye's syndrome within the first 2 years of life. After 3 years of age, patients with CDSP may present with cardiomyopathy and muscle weakness. A linkage with D5S436 in 5q was reported in a family. A recently cloned homologue of the organic cation transporter, OCTN2, which has sodium-dependent carnitine uptake properties, was also mapped to the same locus. We screened for mutation in OCTN2 in a confirmed CDSP family. One truncating mutation (Trp132Stop) and one missense mutation (Pro478Leu) of OCTN2 were identified together with two silent polymorphisms. Expression of the mutant cDNAs revealed virtually no uptake activity for both mutations. Our data indicate that mutations in OCTN2 are responsible for CDSP. Identification of the underlying gene in this disease will allow rapid detection of carriers and postnatal diagnosis of affected patients.

Amino Acid Sequence↗
PubMed1999

Classical galactosaemia in Chinese: A case report and review of disease incidence.

We report a case of galactose-1-phosphate uridyl transferase (GALT) deficiency in a full-term Chinese neonate, who presented with atypical biochemical features of hyperammonaemia in addition to the classical presenting features of jaundice and lethargy after feeding. Red cell GALT activity was virtually absent in the patient while 50% of normal activity was found in parents and a sibling. Mutation screening excluded both Q188R and N314D as the causative mutation in GALT gene, which suggested a possible genetic segregation among ethnic groups. Data from a Taiwan screening program suggested that the incidence of the disease was approximately 1 in 400 000 in the Chinese population which was a sixth of that in Caucasian populations.

Ammonia↗
PubMed1999

Increased fetal DNA concentrations in the plasma of pregnant women carrying fetuses with trisomy 21.

BACKGROUND: The recent discovery of the presence of circulating cell-free fetal DNA in maternal plasma opens up new prenatal diagnostic applications and provides new avenues for clinical investigation. It is of research and potential diagnostic interest to determine whether fetal trisomy 21 may be associated with quantitative abnormalities of circulating fetal DNA in maternal plasma. METHODS: Maternal plasma samples were prospectively collected from two centers situated in Hong Kong and Boston. Samples collected from Boston consisted of 7 women carrying male trisomy 21 fetuses, 19 carrying euploid male fetuses, and 13 carrying female fetuses. Samples collected from Hong Kong consisted of 6 women carrying male trisomy 21 fetuses, 18 carrying euploid male fetuses, and 10 carrying female fetuses. Male fetal DNA in maternal plasma was measured using real-time quantitative Y-chromosomal PCR. RESULTS: For patients recruited from Boston, the median circulating fetal DNA concentrations in women carrying trisomy 21 and euploid male fetuses were 46.0 genome-equivalents/mL and 23.3 genome-equivalents/mL, respectively (P = 0.028). For patients recruited from Hong Kong, the median circulating fetal DNA concentrations in women carrying trisomy 21 and euploid male fetuses were 48.2 genome-equivalents/mL and 16.3 genome-equivalents/mL, respectively (P = 0.026). None of the samples from women carrying female fetuses had detectable Y-chromosomal signals. CONCLUSIONS: Abnormally high concentrations of circulating fetal DNA are found in a proportion of women carrying fetuses with trisomy 21. The robustness and reproducibility of real-time PCR analysis of maternal plasma makes it a valuable tool for cross-institutional collaboration involving centers located in different parts of the world.

Biomarkers↗
PubMed1998

Prenatal diagnosis of fetal RhD status by molecular analysis of maternal plasma.

BACKGROUND: The ability to determine fetal RhD Status noninvasively is useful in the treatment of RhD-sensitized pregnant women whose partners are heterozygous for the RhD gene. The recent demonstration of fetal DNA in maternal plasma raises the possibility that fetal RhD genotyping may be possible with the use of maternal plasma. METHODS: We studied 57 RhD-negative pregnant women and their singleton fetuses. DNA extracted from maternal plasma was analyzed for the RhD gene with a fluorescence-based polymerase-chain-reaction (PCR) test sensitive enough to detect the RhD gene in a single cell. Fetal RhD status was determined directly by serologic analysis of cord blood or PCR analysis of amniotic fluid. RESULTS: Among the 57 RhD-negative women, 12 were in their first trimester of pregnancy, 30 were in their second trimester, and 15 were in their third trimester. Thirty-nine fetuses were RhD-positive, and 18 were RhD-negative. In the samples obtained from women in their second or third trimester of pregnancy, the results of RhD PCR analysis of maternal plasma DNA were completely concordant with the results of serologic analysis. Among the maternal plasma samples collected in the first trimester, 2 contained no RhD DNA, but the fetuses were RhD-positive; the results in the other 10 samples were concordant (7 were RhD-positive, and 3 RhD-negative). CONCLUSIONS: Noninvasive fetal RhD genotyping can be performed rapidly and reliably with the use of maternal plasma beginning in the second trimester of pregnancy.

Blood Grouping and Crossmatching↗