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Biomedical subjects

B Jensen

Publications and source records attributed to B Jensen.

At least 91 records · Page 5Linked to original sources
PubMed1991

Gestational age in relation to marine n-3 fatty acids in maternal erythrocytes: a study of women in the Faroe Islands and Denmark.

Gestation is longer in Faroese than Danish women, possibly because of the high intake of marine long-chain n-3 fatty acids that down regulates formation of prostaglandins from arachidonic acid. Polyunsaturated fatty acids were quantified in erythrocytes obtained within 2 days of delivery from randomly selected groups of 62 Faroese and 37 Danish women with an assessable gestational age. Average ratio of long-chain n-3 fatty acids to arachidonic acid [(3/6) ratio] was 0.73 (SD = 0.11) in Faroese women and 0.61 (SD = 0.12) in Danish women (p less than 0.0001), corresponding to the higher intake of marine n-3 fatty acids in the Faroes. A 20% increase in the (3/6) ratio was associated with an increase in pregnancy duration of 5.7 days in Danish women (95% confidence interval, 1.4 to 10.1 days; p = 0.02) and 0.7 days in Faroese women (95% confidence interval, -2.0 to 3.3; p = 0.6). The hypothesized exposure-effect relationship may be weaker or absent at the higher level of exposure seen in the Faroese group.

Arachidonic Acid↗
PubMed1991

Measurement of transcutaneous PO2, PCO2 and skin blood flow at different probe temperatures using mass spectrometry.

Transcutaneously measured partial pressures of oxygen and carbon dioxide (PtcO2, PtcCO2) approximate the corresponding arterial values at a probe temperature of 44 degrees C. The temperature-dependent increase of PtcO2 and PtcCO2 is caused by an increased skin perfusion, a decrease in the mean diffusion path, a change of skin metabolism, a decrease of tissue solubility of oxygen and carbon dioxide and a right shift of the oxygen and carbon dioxide binding curves of blood. Seven healthy volunteer test subjects participated in the study. A transcutaneous probe connected to a mass spectrometer was placed on the earlobe of the test subject. Four measurements of the transcutaneous PO2, PCO2 and skin blood flow (from the washout kinetics of argon) were determined on each test subject. The first measurement was made with a transcutaneous probe temperature of 37 degrees C. The probe temperature was then increased to 44 degrees C before the next determination. Finally, two determinations were made at 37 degrees C, separated by a time interval of 1 h. The PtcO2 and skin blood flow increased when the probe temperature increased from 37 degrees C to 44 degrees C. However, when the probe temperature was decreased again from 44 degrees C to 37 degrees C, the estimated skin blood flow returned to the initial value while the PtcO2 remained unchanged. It required a further 1 h before the PtcO2 returned to the initial value at 37 degrees C. The most likely explanation of the experimental results is that heating of the skin to 44 degrees C causes a reversible decrease in the skin metabolism.

Adult↗
PubMed1990

Effects of variation in systemic blood pressure on intraosseous pressure, PO2, and PCO2.

Several regulatory mechanisms have been shown to influence the intraosseous circulation. The influence of general hypovolemia on bone circulation and possible regulatory effects were investigated by recording the intraosseous pressure and PO2 and PCO2 continuously by mass spectrometry in rabbits. Hypovolemia was induced by repeated bleedings. The intraosseous and arterial pressures were found to be linearly related. The intraosseous PO2 already decreased after the first step of bleeding and decreased more than 50% of the initial value after an average blood loss of 40 ml. The intraosseous PCO2 showed an opposite pattern. The experimental PO2 vs. arterial pressure curves were similar to curves obtained by a computer simulation that assumes the blood flow to be proportional to the intraosseous pressure.

Animals↗
PubMed1990

Fish oil versus arachis oil food supplementation in relation to pregnancy duration in rats.

Throughout pregnancy, Lewis rats were fed standard rat chow supplemented with 15% (w/w) of either MaxEPA fish oil (FO) or arachis oil (AO); a third group was fed standard rat chow only (St) (n = 15, 15, and 16 rats, respectively). Compared to AO-rats, FO-rats had substantially higher levels of n-3 fatty acids and lower levels of n-6 fatty acids in maternal and fetal tissues at delivery. FO-rats had a longer average gestational age than AO-rats (p less than 0.01), primarily due to a high proportion of AO-rats with short gestations. Birthweights of FO-rats were lower than those of AO-rats (p less than 0.05), which may be related to the lower maternal weight gain during pregnancy and the lower food consumption observed in FO-rats (p less than 0.01). Litter size and occurrence of stillborn pups were not significantly different in the groups (p greater than 0.1). The findings are compatible with the hypothesis that gestational age is positively related to a high dietary intake of n-3 fatty acids.

Animals↗
PubMed1990

DNA gyrase gyrA mutations in ciprofloxacin-resistant strains of Staphylococcus aureus: close similarity with quinolone resistance mutations in Escherichia coli.

The gyrA genes isolated from three ciprofloxacin-resistant clinical isolates of Staphylococcus aureus carried codon 84 (serine----leucine) and/or codon 85 (serine----proline) mutations that were absent in pretreatment susceptible strains. These substitutions occur in a region of the gyrase A protein wherein directly analogous mutations of serine 83----leucine and alanine 84----proline in Escherichia coli confer quinolone resistance. Thus, DNA gyrase A subunit mutations are implicated in resistance to ciprofloxacin in S. aureus.

Amino Acid Sequence↗
PubMed1990

Emergence of ciprofloxacin resistance in nosocomial methicillin-resistant Staphylococcus aureus isolates. Resistance during ciprofloxacin plus rifampin therapy for methicillin-resistant S aureus colonization.

We initiated a randomized, single-blinded trial of ciprofloxacin plus rifampin vs sulfamethoxazole and trimethoprim plus rifampin in the therapy for patients who underwent colonization with methicillin-resistant Staphylococcus aureus (MRSA). Patients who were colonized with MRSA received 2 weeks of either regimen. The study was terminated after the enrollment of 21 subjects due to the recognition of ciprofloxacin resistance in 10 of 21 new MRSA isolates during the last 2 months of the study. Five of the 10 patients with ciprofloxacin-resistant MRSA isolates had never received ciprofloxacin. Long-term (6-month) eradication had been achieved in only three of 11 ciprofloxacin plus rifampin and four of 10 sulfamethoxazole and trimethoprim plus rifampin recipients. The use of this new fluoroquinolone for the eradication of MRSA colonization is usually not effective and may risk the development of ciprofloxacin resistance in MRSA within the hospital environment.

Anti-Bacterial Agents↗
PubMed1990

Decision-making processes of youth.

Research supports the theory that after administrators make a decision, feedback, both positive and negative, and also the administrators' perceived security vis-à-vis their position affect their level of commitment to a course of action. However, this research fails to recognize that subjects of college age playing administrators in the simulated, experimental treatments which have been presented in the research had nothing personally to lose if they made a bad decision--an orientation contradictory to the reality of most actual administrative positions. Additionally, the research ignores the interactional effects of the personality of decision makers in terms of their anxiety levels and the judgments they make. This study took both of these considerations into account by creating a decision-making situation within which prospective administrators made monetary commitments to long-term goals while their anxiety level, both as a basic personality attribute and an index of the reality of the decision-making process, was monitored under conditions of varying levels of job insecurity and resistance to their policies in relation to their decisions. Analyses revealed that contrary to the results of past research which used college students as subjects: (1) there is a significant negative correlation between levels of anxiety and commitments to previously chosen courses of action; (2) there are no significant effects of job security on commitment; and, most importantly, (3) high resistance to a policy decision leads to significantly less monetary commitments to long-term goals. The findings suggest that the basis for the contradictory results lies with the anxiety level of decision makers and the realism of experiencing a loss by making poor decisions.

Achievement↗
PubMed1989

Enzyme activity electrophoresis: development and applications.

The development of rocket enzyme activity electrophoresis for the detection and quantification of various proteinases, lipases and pectinases is presented. Rocket enzyme activity electrophoresis is more sensitive than the radial diffusion assay and often enables distinction between qualitatively different enzymes present in the same samples, whereas the radial diffusion assay only provides information on the overall enzyme activity. However, calibration and optimization of the enzyme activity electrophoretic assay have to be performed for each new enzyme-substrate system to be analyzed. Some of the common pitfalls in the development of new enzyme activity electrophoretic assays are presented. Enzyme activity electrophoresis can be applied in combination with other electrophoretic assays. Particularly the combination of enzyme activity electrophoresis with various immunoelectrophoretic methods can provide detailed information on the enzymes studies.

Electrochemistry↗
PubMed1989

Effect of amiloride on arachidonic acid and histamine release from rat mast cells.

The effect of a putative Na+/H+ exchange inhibition on histamine and [14C]arachidonic acid ([14C]AA) release has been examined in rat peritoneal mast cells, using either addition of amiloride or removal of extracellular Na+. The cells were stimulated by non-immunological agents, i.e. calcium ionophore A23187, nerve growth factor (NGF), thapsigargin and compound 48/80. On the basis of the results obtained, a possible role for Na+/H+ exchange in rat mast cell secretion is discussed.

Amiloride↗
PubMed1989

Arginine vasopressin stimulates phosphoinositide turnover in an enriched rat Leydig cell preparation.

An enriched rat Leydig cell preparation was preincubated with [14C]arachidonic acid. Stimulation of the cells with arginine vasopressin (AVP) (1 microM) for 2 min caused a significant increase in labelled phosphatidic acid and a significant fall in radioactivity in phosphatidylinositol and phosphatidylinositol 4-monophosphate + phosphatidylinositol 4,5-bisphosphate. Preincubation with dibutyryl cyclic AMP had no effect on the AVP-induced phospholipid turnover. Leydig cells were preincubated with myo-[2-3]inositol for 22 h and then with 10 mM LiCl for 10 min. Exposure to AVP (1 microM) induced a rise in labelled inositol phosphates. The response was inhibited when the cells were preincubated with the phorbol ester, 4 beta-phorbol 12-myristate 13-acetate (0.16 microM) for 10 min. These results provide evidence for an AVP-induced phospholipase C stimulation in rat Leydig cells and suggest a protein kinase C-dependent feedback inhibition of the stimulation. Other agonists that might have a regulatory function in the testis were tested for possible effects on phosphoinositide metabolism. Of prostaglandin E2 (10 microns,) angiotensin II (0.1 microM), and bradykinin (0.9 microM), only the latter induced a significant increase in the labelled inositol phosphates. This suggests that Leydig cells possess a bradykinin receptor which can activate phospholipase C.

Animals↗
PubMed1989

Pregnancy duration and the ratio of long-chain n-3 fatty acids to arachidonic acid in erythrocytes from Faroese women.

Dietary long-chain n-3 fatty acids (FA) may prolong gestation by inhibiting formation of prostaglandins from arachidonic acid. FA were quantified in phosphatidylcholine (PC), phosphatidylethanolamine (PE), and total lipids (TL) of red cells sampled during pregnancy from 29 Faroese women. The ratio of long-chain n-3 FA to arachidonic acid (the (3/6) ratio) was used as the most relevant single measure of exposure. In 18 women with certain gestational age and with spontaneous onset of delivery, gestational age was significantly associated with the (3/6) ratio quantified in PC (correlation coefficient 0.50, P = 0.035), but not with the (3/6) ratio in PE (correlation coefficient 0.21, P = 0.40) or TL (correlation coefficient 0.29, P = 0.26). The association with the (3/6) ratio in PC could not be attributed to confounding by maternal age, weight, marital status or smoking.

Arachidonic Acids↗
PubMed1989

A new method for the estimation of mutans streptococci in human saliva.

A new method for quantitating the numbers of mutans streptococci in saliva--the "Strip mutans" test--was developed. It includes the following steps: A prepared plastic spatula is contaminated with saliva, transferred to a selective broth, incubated for two days, and dried. A predetermined area is counted or evaluated for CFUs of mutans streptococci. The medium contains sucrose to promote adhesion of mutans streptococci to the strip. Bacitracin, added just before use, is the basis for the selectivity. Results with the new medium were compared with those from the "spatula technique" and with those from conventional saliva sampling with dilution. The studies involved 302 and 60 schoolchildren, respectively. There was a highly significant correlation between the results from the new method and those from conventional methods. The strip mutans test is easy to used and has long shelf-life, and the spatulas with adherent colonies can be saved for future comparisons.

Child↗
PubMed1988

Inhibition by amiloride and by Na+-depletion of A23187-stimulated arachidonic acid and histamine release from rat mast cells.

Rat peritoneal mast cells, labelled with [14C]arachidonic acid, released histamine and [14C]arachidonic acid upon the addition of A23187. The release induced by low concentrations of A23187 was suppressed by removal of extracellular Na+ and by addition of the Na+/H+ exchange inhibitor, amiloride. Addition of protein kinase C inhibitors resulted in only a modest decrease of [14C]arachidonic acid and histamine release. [14C]Arachidonic acid was hydrolyzed from both phosphatidylcholine and triacylglycerol. Amiloride inhibited only the hydrolysis from phosphatidylcholine. It is suggested that an Na+/H+ exchange is stimulated secondary to an A23187-induced increase in intracellular calcium concentration. Increased Na+/H+ exchange seems to facilitate the activation by intracellular calcium ions of phospholipase A2 as well as of histamine secretion.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Structures of acetylcholine picrate and methoxycarbonylcholine picrate hemihydrate.

Acetylcholine picrate, C7H16NO2+.C6H2N3-O7-, Mr = 374.3, orthorhombic, Pbca, at 105 K: a = 18.799 (4), b = 7.726 (2), c = 22.878 (4) A, V = 3323 (2) A3, Z = 8, Dm(295 K, flotation) = 1.44, D chi(105 K) = 1.496 Mg m-3, mu(Mo K alpha) = 0.120 mm-1, F(000) = 1568, m.p. (hot-stage microscope) 381-382 K, R = 0.048 for 1049 observed [I greater than or equal to 3.0 sigma(I)] reflections. Methoxycarbonylcholine picrate hemihydrate, C7H16NO3+.C6H2N3O7-.1/2H2O, Mr = 399.3, monoclinic, P2/n, at 105 K: a = 11.337 (16), b = 7.279 (2), c = 21.424 (13) A, beta = 103.01 (7) degrees, V = 1723 (4) A3, Z = 4, Dm(295 K, flotation) = 1.49, D chi(105 K) = 1.539 Mg m-3, mu(Mo K alpha) = 0.126 mm-1, F(000) = 836, m.p. (hot-stage microscope) 391-391.5 K, R = 0.033 for 6359 observed [I greater than or equal to 3.0 sigma(I)] reflections. The acetylcholine ion as well as the methoxycarbonylcholine ion have as first neighbours a great number of oxygen atoms. Contacts to the quaternary ammonium group do not seem to be more important than contacts to the acetyl or methoxy-carbonyl moieties. No direct contacts between aromatic rings and quaternary ammonium groups are found.

Acetylcholine↗
PubMed1988

Electromyography and fatigue during prolonged, low-level static contractions.

Findings from five separate studies of EMG changes and muscle fatigue during prolonged low-level static contractions are summarized, and the possible mechanisms behind the changes are briefly discussed. Sustained static contractions (10%, 7% and 5% MVC) of up to 1 h duration were performed by finger flexors, elbow flexors and extensors, and knee extensors. In one experiment, intermittent static arm pulling (triceps) (10 s contraction and 5 s rest, average work load 14% and 10% MVC) was performed for 7 h. The endurance time for the sustained contractions was around one hour for 10% MVC, and it was shown--all in all--that the concept of "indefinite" endurance times at contractions below 15-20% MVC cannot be maintained. After 5% MVC sustained contractions for one hour a 12% reduction in MVC was seen, and significant increases in EMG amplitude and decreases in the mean spectral frequency of the EMG-power spectrum were found. Marked differences were also seen in the EMG changes in the elbow flexors and extensors, and transcutaneous electrical stimulation of the knee extensors showed that low frequency fatigue was present after the contraction. With intermittent contractions similar changes in the EMG parameters were seen after 2-3 h of contractions at 14% MVC. On average, during contractions of 10% MVC no EMG changes were detected. Increased extracellular potassium concentration in the contracting muscles is suggested as a possible explanation of these findings.

Electromyography↗
PubMed1988

Automated turbidimetry for rapid determination of the bacteriological quality of raw meat and processed meat products.

A fully automated centrifugal spectrophotometer for turbidimetric measurements linked to a computer for data processing was used to record and analyze growth of different types of bacteria associated with spoilage of raw meat and processed meat products (sliced meat for sandwiches) in order to predict bacterial counts. Media for this specific analysis were developed to enumerate total viable count, lactic acid bacteria. Brochothrix thermosphacta and Pseudomonas spp. Correlation coefficients of -0.91 to -0.97 were obtained between the conventional plate count technique and the turbidimetric method (linear regression). Lactic acid bacteria in the range 10(3) to 10(9) cfu/g could be detected within 48 h, whereas total viable count, Brochothrix thermosphacta and Pseudomonas spp. generally could be detected within 24 h. Counts exceeding 10(7) cfu/g could be detected within 6 h.

Autoanalysis↗