Search PubMed⌕ Search

Biomedical subjects

H R Christensen

Publications and source records attributed to H R Christensen.

At least 19 recordsLinked to original sources
PubMed2000

Development of a polyclonal antibody-based sensitive enzyme-linked immunosorbent assay for fumonisin B(4).

Polyclonal antibodies (PAb) against fumonisin B(4) (FmB(4)), which have good cross-reactivity with four major fumonisins, were produced by immunizing a rabbit with FmB(4)-keyhole limpet hemocyanin conjugate. A sensitive competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for fumonisins was developed. Because of the limited supply of FmB(4), both FmB(1)-horseradish peroxidase conjugate (HRP) and FmB(3)-HRP were tested as the toxin-enzyme markers in the CD-ELISA. In the FmB(1)-HRP-based CD-ELISA, the concentrations of FmB(1), FmB(2), FmB(3), and FmB(4) causing 50% inhibition of binding of enzyme marker (IC(50)) were 9.0, 2.1, 9.0, and 6.5 ng/mL (or the relative cross-reactivities toward FmB(1), FmB(2), FmB(3), and FmB(4) were 58.5, 309.5, 58.5, and 100%), respectively. In the FmB(3)-HRP-based CD-ELISA, the IC(50) values for FmB(1), FmB(2), FmB(3), and FmB(4) were 7.1, 1.9, 7.6, and 5.3 ng/mL (or the relative cross-reactivities toward FmB(1), FmB(2), FmB(3), and FmB(4) were 74, 280, 70, and 100%), respectively. The FmB(3)-HRP-based CD-ELISA was then used in a series of analytical recovery experiments using Fusarium moniliforme corn culture material spiked with FmB(1) and with clean corn spiked with a FmB(3)/FmB(4)-containing extract. The overall recovery of FmB(1) from culture material in the range of 10-100 ppm was 65%. The detection limit for FmB(1) with clean corn as matrix was between 100 and 500 ppb. F. moniliforme cultures were analyzed with the developed CD-ELISA and a well-established FmB(1) antibody-based ELISA, which is not sensitive to FmB(4). Differences in the fumonisin levels found by the two assays were used as an indication of the presence of FmB(4) in the culture material and, therefore, as a method to identify FmB(4)-producing strains. Using ELISA in combination with HPLC individual B-series fumonisins were quantified. The ELISA developed in the present study would be a useful supplement to FmB(1) antibody-based ELISA for screening of Fusarium strains for the production of major fumonisins.

Animals↗
PubMed2000

Bioavailability and pharmacokinetics of isradipine after oral and intravenous administration: half-life shorter than expected?

Isradipine is a calcium channel-blocking agent of the dihydropyridine type, used in the treatment of hypertension. A terminal half-life of 8-9 hr has been reported, in several pharmacokinetic studies after oral administration of isradipine. In a yet unpublished study a much shorter half-life was observed, and the present trial was therefore conducted in order to estimate the half-life after intravenous administration of isradipine. The bioavailability was estimated as well. In a randomised cross-over design ten healthy young volunteers were given either isradipine orally or an intravenous infusion. The two study periods were separated by at least 3 days. Blood samples for measurement of isradipine concentration were collected for 10-12 hr after administration and half-life and bioavailability were estimated. Mean terminal half-life after intravenous administration was calculated to be 2.8 hr, and the bioavailability to be 0.28. None of the 10 subjects suffered from side effects. In the present intravenous study the half-life of isradipine seems to be of much shorter than demonstrated in previous oral studies.

Administration, Oral↗
PubMed1999

[Gamma-hydroxybutyrate--an endogenous substance and a new central nervous system stimulant. Clinical aspects of acute poisoning].

During the last six months, the Poison Control Centre at Bispebjerg Hospital, Copenhagen, Denmark, has observed an increasing number of patients intoxicated with GHB, a drug of abuse. The patients are often admitted to the emergency ward shortly after having taken the drug, unconscious or comatose. If younger patients present with these symptoms, intoxication with GHB should be seriously considered. The effects are seen within 15 to 30 minutes after oral ingestion of the drug. Spontaneous recovery usually occurs within three to five hours. The most common effects are mild euphoria, sedation, vomiting, somnolence, bradycardia, aggressive behaviour, apnoea, respiratory depression, and coma. Normally the patient breathes adequately, but insufficient respiration may occur and deaths have been described. The drug is often consumed together with alcohol and other drugs of abuse, which strengthens the effect of GHB. Treatment is symptomatic. A review of the literature with special emphasis on clinical effects included toxicology and treatment is given.

Central Nervous System Stimulants↗
PubMed1999

[Amphetamine, ecstasy and cocaine. Clinical aspects of acute poisoning].

Consumption of the illicit drugs amphetamine, ecstasy and cocaine is increasing in Denmark and Europe leading to an increasing number of intoxications with these drugs. Abroad, several deaths after ingestion of a few doses of the drugs have been reported. Amphetamine, ecstasy and cocaine increase the amount of dopamine, norephedrine and serotonine in the nervous system, resulting in CNS stimulation and a general sympathomimetic stimulation. Symptoms to be treated originate mainly from the CNS and the cardiovascular system, and present as tachycardia, hypertension and seizures, later hypotension and coma. Hyperpyrexia, rhabdomyolysis and affections of the kidneys, lung and liver function are also often seen. Hyperpyrexia is an important marker of poor prognosis, and must be handled aggressively. A review of the literature concerning the optimal treatment based on pharmacological and diagnostic considerations is given in the article.

Amphetamine↗
PubMed1999

[Clinical pharmacological drug information. Well over one year's experience].

Clinical pharmacology was established quite recently in Denmark as a medical specialty. It comprises--among other items--clinical pharmacological drug information service, the primary aim of which is to provide service to health personnel with clinical responsibility involving drugs and specific patient-related questions. Questions forwarded to the clinical pharmacological drug information service at two Copenhagen hospitals have been summarized. The questions were categorized according to the profession and the affiliation to the health care system of the inquirer as well as the nature of the question. At the two hospitals, 118 and 77 questions were answered from January 1st 1997 to June 1st 1998, respectively. Physicians employed at hospitals were responsible for the majority of the questions. Most questions concerned adverse drug reactions, choice of therapy/drug, and therapy during pregnancy or breast feeding.

Denmark↗
PubMed1998

[Discrepancies between medical records and dispensing records in two large hospital departments in Copenhagen].

This study was performed to investigate the possible differences between prescribed medicine, as entered in the hospital record, and the medicine dispensed to the patients according to the nurse's dispensing records (NDR's) in two clinical departments at a Copenhagen University Hospital. Discrepancies were defined as either dosage differences or drugs only present in one file, and were divided into major and minor discrepancies, according to clinical significance. In the first department, discrepancies were found in 61.4% of the records, and major discrepancies were found in 35.1%. In the second department, discrepancies were found in 70.5% of the cases, and major discrepancies in 42.5%. No correlation was found between the number of drugs per patient and the number of discrepancies. A significant difference exists between what is prescribed, and what is dispensed. This can have clinical as well as legal consequences.

Denmark↗
PubMed1998

Enantioselective determination of isradipine in human serum using chiral stationary phase liquid chromatography and gas chromatography with nitrogen selective detection.

rac-Isradipine is a dihydropyridine type calcium antagonist. Its calcium entry blocking effect is due primarily to the (+)-(S)-enantiomer. This study describes a sensitive enantioselective method for the determination of isradipine in human serum. Following alkaline extraction into hexane, the enantiomers of isradipine are separated quantitatively by high-performance liquid chromatography on a Chiralcel OJ column at 39 degrees C. The collected fractions were evaporated and assayed using capillary gas chromatography on a HP 50+ column with nitrogen selective detection. Using 2.0 ml of serum, 0.7 nmol/1 (0.26 ng/ml) of each enantiomer could be determined with acceptable precision. The method has successfully been used to measure (+)-(S)- and (-)-(R)-isradipine concentrations in samples from volunteers after intravenous and oral administration of isradipine.

Calcium Channel Blockers↗
PubMed1997

Smoking related to 24-h ambulatory blood pressure and heart rate: a study in 352 normotensive Danish subjects.

This study shows the association between smoking and both office and ambulatory blood pressure. By means of stratification, a uniform number of subjects of both sexes and spanning 6 decades (aged 20 to 79 years) were recruited randomly from the local community register. A total of 352 subjects participated, including 161 smokers. Smokers (both sexes and all age groups summed), as compared with nonsmokers had statistically significant lower office blood pressure as follows (mean systolic +/- SED/mean diastolic +/- SED): (systolic and diastolic, -6.8 +/- 2.1/-3.9 +/- 1.3); day ambulatory blood pressure (diastolic, /-2.8 +/- 1.0); and night ambulatory blood pressure (systolic and diastolic, -4.2 +/- 1.8/-3.9 +/- 1.1). The intraperson variability of the day ambulatory blood pressure (as measured every 15 min) was identical for the smokers and the nonsmokers. Smokers were found to have a diminished "white coat" effect; this diminished white coat effect has not previously been described. The major white coat effect was seen in the older nonsmokers, whereas the diminished white coat effect was most pronounced in the older male smokers and in the younger female smokers. Smokers seem to have a diminished white coat effect, as well as a lower ambulatory blood pressure throughout the day (diastolic) and at night (systolic and diastolic). The similar intraperson variability found in the smokers' and nonsmokers' blood pressure further speaks for a consistently lower blood pressure in smokers as compared with nonsmokers.

Adult↗
PubMed1996

[Round-the-clock blood pressure measurements in 352 persons--a reference material].

The aim of this study was to establish reference values for 24-hour ambulatory blood pressure in a Danish population stratified for gender and age in the decades from 20 to 79 years of age. A sample of 352 persons, 179 men and 173 women randomly selected from the local community register, age 20-79 years underwent 24-h ambulatory blood pressure monitoring. For men age < 50 daytime ambulatory blood pressure (median) was 125/79 mmHg and night time was 106/65 mmHg, for women the respective pressures were 113/77 mmHg and 97/64 mmHg. For men age > or = 50 daytime ambulatory blood pressure was 133/83 mmHg and night time was 124/86 mmHg, for women the respective pressures were 122/83 mmHg and 105/65 mmHg. Presently, we can only relate cardiovascular risk to clinic blood pressure. Therefore we have calculated corresponding ambulatory blood pressure values to WHO's upper limit 160/90 mmHg for normal blood pressure in the clinic and found 154/87 mmHg for daytime and 134/74 mmHg at night. For a clinic pressure of 95 mmHg the corresponding daytime value was 91 mmHg, for 100 mmHg it was 95 mmHg.

Adult↗
PubMed1995

Aminoglycosides: single or multiple daily dosing? A meta-analysis on efficacy and safety.

A number of randomised studies indicate that a single high dose of aminoglycoside every 24 h may be more efficient and less toxic than the same dose divided into multiple daily doses. In the meta-analysis of 16 studies described here, which included more than 1200 patients, the relative chance (i.e. the relative risk, RR) of cure of the single-dose regime compared with the multiple-dose regime was 1.027, indicating that the single daily dose regime had a 2.7% higher cure rate (NS). The RR of avoiding nephrotoxicity was 1.001 (NS) and the RR of avoiding ototoxicity was 1.001 (NS). It is concluded that there is no difference concerning efficacy and safety between single-dose and multiple-dose regimes for administration of aminoglycosides.

Aminoglycosides↗
PubMed1995

24-h ambulatory blood pressure in 352 normal Danish subjects, related to age and gender.

UNLABELLED: The study was conducted to determine age and sex stratified normal values for 24-h ambulatory blood pressure. A sample of 352 healthy subjects (all white) were randomly selected from the community register and stratified by sex and age groups in decades from 20 to 79 years of age. Persons with a history of hypertension, cerebral apoplexy, diabetes, myocardial or renal disease, and who were taking blood pressure-influencing medication were excluded. Ambulatory blood pressure was recorded over 24 h, with measurements taken every 15 min from 07:00 to 22:59, and every 30 min from 23:00 to 6:59. Systolic blood pressure increased only slightly with age and was significantly higher in men than in women. The diastolic blood pressure increased only slightly with age in both sexes until the 50 to 59 years age group and declined thereafter. The diastolic blood pressure was not different for the two sexes. Both systolic and diastolic blood pressure were approximately 15% lower during the night regardless of age or sex. Ambulatory blood pressure during the daytime was on an average of 5 mm Hg lower than office blood pressure, but the mean difference between the two measurements increased with age. The variability of the difference also increased with age. IN CONCLUSION: Normal values for ambulatory blood pressure are presented in a randomly selected age- and gender-stratified population. Differences between office blood pressure and ambulatory blood pressure increased with age suggesting that the previously observed higher blood pressure seen in the elderly partly might be explained by a greater impact of white coat hypertension in older people.

Adult↗