Search PubMed⌕ Search

Biomedical subjects

A Jensen

Publications and source records attributed to A Jensen.

At least 91 records · Page 5Linked to original sources
PubMed1995

Improved RNase protection assay for quantifying LDL-receptor mRNA; estimation of analytical imprecision and biological variance in peripheral blood mononuclear cells.

We have improved the protocol for RNA quantification by using RNase protection. Instead of precipitation and extraction with phenol and chloroform, we use a faster and more reliable precipitation based on guanidinium thiocyanate (GdSCN). The internal standard is produced by in vitro transcription of a DNA template constructed so as to allow simultaneous detection of the in vitro transcript and the low-density lipoprotein receptor (LDLR) mRNA by use of the same probe and hybridization. Addition of this internal standard at the step for RNA isolation reduced the analytical imprecision from 40.8% to 19.3%. Estimates of the within- and between-subject biological variations of the LDLR mRNA content in peripheral blood mononuclear cells (PBMCs) isolated from healthy volunteers were 21.5% and 13.6%, respectively, and the analytical imprecision was 22.6%. The mean content of LDLR mRNA in PBMCs from healthy individuals was 0.78 copies per cell.

Chemical Precipitation↗
PubMed1994

Extension of the 2-deoxyglucose method to the fetus in utero: theory and normal values for the cerebral glucose consumption in fetal guinea pigs.

Fetal cerebral metabolism changes during development. The normal fetal metabolic rate must be known to evaluate pathophysiological changes. Therefore, we determined the regional cerebral glucose consumption in the fetal guinea pig. This required the application of the 2-deoxyglucose method to this species. We measured both the transfer coefficients of deoxyglucose and glucose between the maternal arterial plasma and the fetal brain and the lumped constant in chronically prepared undisturbed guinea pig dams using a three-compartment model. Furthermore, the ratio between the initial clearances of deoxyglucose and glucose between the maternal arterial plasma and the fetal brain and the ratio between the phosphorylation coefficients of these substrates in the fetal brain were determined. The total cerebral glucose consumption measured by the deoxyglucose method (10 +/- 1.2 mumol/100 g/min) was similar to that calculated from the glucose concentration and the phosphorylation coefficient of glucose in the cerebrum (10 +/- 0.4 mumol/100 g/min). We conclude that the 2-deoxyglucose method is applicable to the guinea pig, and we further conclude that in the fetal guinea pig cerebral glucose consumption is 10 times lower than that in the adult.

Animals↗
PubMed1994

Risk factors for listeriosis in Denmark, 1989-1990.

Dietary risk factors for listeriosis were examined, and the risk levels of listeriosis according to specific underlying diseases were evaluated, in order to study the basis for prevention. Questionnaires from 50 listeriosis patients and 40 matching control persons were analysed. Unpasteurized milk was a risk food for sporadic listeriosis, and an outbreak of a European epidemic strain of Listeria monocytogenes was obviously linked to a blue-mould cheese or a hard cheese. Leukaemia, AIDS and renal transplantation were found to be associated with > 1000-fold risk of acquiring listeriosis, compared with healthy persons. As a part of prevention, persons running a high risk of contracting listeriosis should be individually informed about food hygiene and risk foods.

Adult↗
PubMed1994

Epidemiology of toxic shock syndrome toxin-1 production in Staphylococcus aureus strains isolated in Denmark between 1959 and 1990.

A total of 436 Staphylococcus aureus bacteremia strains isolated between 1959 and 1990 were tested for the production of toxic shock syndrome toxin-1 (TSST-1) by a semiquantitative reversed passive latex agglutination test. TSST-1 production was found in 147/260 (57%) of phage group I strains, excluding the "80" complex, and in 17/176 (10%) of non-group I strains. Strains of the 52, 52A, 80, 81 complex ("80" complex), constituting a subgroup of group I, did not have the same high frequency of TSST-1 production as the rest of group I strains (4% versus 57%). The "80" complex has almost disappeared in Denmark. TSST-1 production was found with the same high frequency among group I strains from the beginning (1959) and throughout the observation period. The TSST-1 production was associated with the phages 29 and/or 52, which in turn lysed 95% of group I strains. The TSST-1 production was quantitatively greater in the phage group I strains than in the non-group I strains. TSST-1 production of the bacteremia strains was not correlated to the clinical parameters: mortality, age, gender, bacterial focus, underlying diseases, or whether the infection was hospital or community acquired.

Bacterial Toxins↗
PubMed1993

[Importance of surgical masks for peroperative asepsis].

For more than 70 years, the surgical mask has been used under operations as part of the maintenance of aseptic conditions in the operational field. Experiments with models and investigations of sources of infection carried out over the past 20 years have shown, however, that the bacterial flora of the upper respiratory tract do not contribute to airborne contamination of the surgical wound, but that persons who are situated directly beside the field may contaminate the wound directly by droplets released by speech, sneezing or coughing. Over the last ten years the usefulness of the surgical mask has been disputed several times, and a few controlled clinical trials have been able to confirm any benefits associated with use of surgical masks. There is therefore no reason from the point of view of preventing infection to maintain a general requirement for the use of surgical masks by others than those persons who may be situated within an arm's length of the operational field or instrument table.

Asepsis↗
PubMed1993

Autonomic modulation of insulin levels in foetal sheep.

The autonomic nervous system plays an important part in metabolic and circulatory adaptation of the foetus to changes in its intrauterine environment and after delivery. Foetal and neonatal glucose metabolism and insulin secretion are influenced by changes in humoral catecholamine levels as they may occur during asphyxia. To assess the role of neuronal and humoral sympathetic activity in foetal endocrine pancreatic regulation, chronically catheterized foetal sheep near term were chemically sympathectomized with 6-hydroxydopamine. Experiments were carried out in unanaesthetized foetal sheep in utero in the absence of uterine contractions. Insulin and glucose levels, blood gases, acid-base status and catecholamines were measured before, during and after a 2 min occlusion of uterine blood flow caused by mechanical constriction of the maternal aorta. Pancreatic blood flow was determined using radioactive labelled microspheres. During normoxaemia, insulin levels, pancreatic blood flow and glucose transport to the organ in sympathectomized foetuses were elevated compared with intact animals, whereas glucose concentrations did not show any significant differences. After the onset of asphyxia humoral catecholamine levels rose significantly in both groups. Insulin concentrations in the plasma of both intact and sympathectomized foetuses were no longer different indicating both indirect (blood flow and humoral catecholamine related) and direct (neurally mediated) sympathetic effects on pancreatic beta cells.

Animals↗
PubMed1993

Listeria monocytogenes isolation from human faecal specimens: experiments with the selective media, PALCAM and L-PALCAMY.

The selective media PALCAM and L-PALCAMY were evaluated for their potential ability to detect Listeria monocytogenes in faeces. Recovery on PALCAM was almost total, and similar at 30 degrees C and 35 degrees C with or without CO2 incubation. Warm enrichment in L-PALCAMY was necessary in order to detect low numbers (< 10(2)/ml faeces). Faeces in excess of 0.25 ml/10 ml L-PALCAMY was inhibitory. The results point to L-PALCAMY and PALCAM as an epidemiological tool.

Culture Media↗
PubMed1993

Cerebral energy metabolism in fetal guinea pigs during moderate maternal hypoxemia at 0.75 of gestation.

There is evidence from fetal sheep near term that cerebral oxygen delivery decreases during a moderate maternal hypoxemia, whereas cerebral oxygen consumption is maintained. However, since in immature fetuses circulatory centralization may be in part ineffective, cerebral concentrations of high-energy phosphates may fall during a moderate maternal hypoxemia due to an insufficient cerebral oxygen supply. On the other hand anaerobic glycolysis may accelerate to prevent the depletion of high-energy phosphates. To determine, whether or not there is an energy failure in the immature fetal brain in this situation, we studied the effects of 60 min moderate maternal hypoxemia on cerebral concentrations of high-energy phosphates and glycolytic intermediates in fetal guinea pigs at 0.75 gestation. Maternal hypoxemia resulted in no change in fetal mixed arterio-venous pH (7.41 +/- 0.05 vs. 7.38 +/- 0.05; n.s.) or PCO2 (39.0 +/- 4.2 vs. 36.4 +/- 5.6 mmHg; n.s.), but in a fall in fetal PO2 (17.3 +/- 2.2 vs. 11.2 +/- 1.9 mmHg; P < 0.01). There was an increase in fetal cerebral concentrations of lactate (1.50 +/- 0.24 vs. 2.82 +/- 0.91 mumol/g; P < 0.01), whereas those of high-energy phosphates remained unchanged. From these results we conclude that during moderate isocapnic hypoxemia cerebral energy metabolism of immature fetal guinea pigs is maintained by an acceleration of the anaerobic glycolytic rate.

Animals↗
PubMed1992

Environmental cadmium in Europe.

The present article reviews information from the latest 10 years concerning fate and exposure of cadmium in the environment, on ecotoxicological effects, and on critical pathways leading to human and environmental exposure. It emphasizes the situation within the Community of European Countries by referring to limit values used in the EEC and some of its member states for emissions to water, air and soil. Estimates have been made on total emission balances for the Netherlands, Denmark, and for the EEC as a whole. The balances show that 70-90% of all cadmium circulating in the Community is disposed of as waste in solid waste deposits. Production and use patterns are presently changing, as indicated by reduced consumption in recent years of cadmium for plating, stabilizers and pigments in several countries as a result of regulations. However, significant increases in consumption for cadmium-containing batteries have occurred, resulting globally in increasing trends for the total consumption and production. Cadmium in sediments is more mobile than described earlier. Aquatic organisms can be classified in order of decreasing accumulation: algae greater than molluscs greater than crustaceans greater than fish. There is no evidence of biomagnification of cadmium within marine or fresh water food webs. Cadmium may enter into plants via roots or by foliar adsorption following atmospheric deposition. Biomagnification in terrestrial food chains is not observed. The uptake into plants is plant specific. Within plants significant variations are seen with concentrations generally decreasing in the order: roots greater than leaves greater than fruiting parts greater than seeds. A compilation of cadmium in air, in the aquatic environment and in soil is given. A downward trend during the 1970s to mid-1980s seems to be evidenced from various Northern European studies on cadmium air concentrations as well as for deposition rates of cadmium. In rivers, the dissolved cadmium concentrations are generally found to be relatively low (10-500 ng/L). In seawater, cadmium concentrations are found at 0.5-10 ng/L in oceanic or open marine areas, while elevated concentrations are reported in more closed marine areas and especially in coastal zones close to polluted estuaries. In fresh water, lake sediments concentrations 3-30 times higher than the background concentrations are reported in the surface layers of sediments. A significant decrease in such pollution has been observed within the recent 10 years. For marine sediments, enrichment factors of two are found in sediments from open areas and locally even 5-10 times.(ABSTRACT TRUNCATED AT 400 WORDS)

Cadmium↗
PubMed1992

[Risk of cerebral hemorrhage in premature and mature newborn infants].

We launched a prospective cranial ultrasound screening study at the Maternity Hospital of the University of Giessen to examine the incidence and severity of brain damage in newborns. More than 90% of all neonates born during 1984-86 were included in the study (n = 2781) and were screened for cerebral abnormalities on 5.9 +/- 3.3 (SD) day post partum. There were in 7.8% sonographic abnormalities, the most frequent being peri/intraventricular haemorrhages (5.2% PIVH of various degrees (grade I-III). Periventricular leucomalacia, porencephalia, subarachnoidal haemorrhages, and hydrocephali were rare (less than or equal to 0.2%). The incidence of PIVH increased progressively with decreasing gestational age, e.g. from 1.5% at 41 weeks up to 61% at 24-30 weeks of gestation. A large percentage of babies with cerebral haemorrhages were clinically normal. There was a close inverse relationship between the Apgar score at 1,5 and 10 min and both incidence and severity of PIVH. However, the relation between PIVH and both cardiotocography (matched-pairs analysis) and arterial cord blood-pH was poor. The incidence of PIVH was increased in growth retarded newborns (pH less than or equal to 7.29), preterm multiples and amnionitis, but not after preeclampsia and premature rupture of membranes. It is interesting to note that, in mature newborns (greater than or equal to 38 weeks), there was no difference in the incidence of PIVH between spontaneous deliveries, vacuum extractions, and Caesarean sections, and that there was no difference between vaginally delivered (1.5%) and sectioned breech presentations (3.5%) in this group. In preterms at 35-37 weeks with protracted labour and secondary Caesarean section, the incidence of PIVH was high (19%). We conclude, that neonatal cranial ultrasound screening is an important tool for risk assessment and quality control in obstetrics. It clearly improves both the quality of the advice given to the patients and the clinical management of high-risk pregnancies.

Acid-Base Equilibrium↗
PubMed1992

Cerebral energy metabolism in immature and mature guinea pig fetuses during acute asphyxia.

In immature fetuses circulatory centralization caused by acute asphyxia is less effective than that in mature fetuses (Jensen & Berger, 1991). This suggests that cerebral oxygenation may be poor in immature fetuses during asphyxia. On the other hand cerebral oxygen consumption is lower in immature than that in mature fetuses. To determine, whether or not there is an imbalance between oxygen supply and demand in one or the other group, we compared the time course of the changes of cerebral concentrations of both high-energy phosphates and glycolytic intermediates between immature and mature guinea pig fetuses during acute asphyxia caused by arrest of uterine blood flow. The fall in the cerebral concentrations of adenosine triphosphate and glucose, and the rise in those of adenosine monophosphate and lactate were slower in immature than in mature fetuses. There were no differences between the levels of cerebral adenosine diphosphate and creatine phosphate of the two groups. From these results we conclude that during acute asphyxia the imbalance between cerebral oxygen supply and demand is less marked in immature than in mature fetuses.

Acute Disease↗
PubMed1992

Foetal circulatory responses to arrest of uterine blood flow in sheep: effects of chemical sympathectomy.

Acute foetal asphyxia, caused by arrest of uterine blood flow, increases both sympathetic activity and peripheral vascular resistance and decreases blood flow to peripheral organs (Jensen et al., J. Dev. Physiol., 9, 543-559). The rapidity and uniformity of this peripheral vasoconstriction suggest that the sympatho-neuronal system may reflexly cause these initial blood flow changes during acute asphyxia. To test this hypothesis, we studied 5 intact and 6 chemically sympathectomized (6-hydroxy-dopamine, 46.1 +/- 6 mg/kg foetal weight) chronically prepared normoxaemic foetal sheep in utero at 0.9 of gestation. Organ blood flows (microsphere method), plasma concentrations of catecholamines, vasopressin, and angiotensin II, acid-base balance and blood gases were measured before, during and after arrest of uterine blood flow for 2 min, i.e., at 0, 1, 2, 3, 4 & 30 min. In intact foetuses there was a progressive increase in arterial blood pressure and a rapid circulatory centralization in favour of the brain stem and heart and at the expense of most of the peripheral organs. The changes in peripheral blood flow during and after asphyxia were well reflected by those in the skin and scalp. In chemically sympathectomized foetuses, arterial blood pressure fell transiently at 1 min of asphyxia and cardiac output was redistributed towards the carcass and intestinal organs at the expense of the heart, spinal medulla, and placenta. We conclude that in foetal sheep at 0.9 of gestation, the short-term adaptation to arrest of uterine blood flow is a rapid and profound peripheral vasoconstriction to effect an increase in arterial blood pressure. This initial response during circulatory centralization, which is necessary to increase or maintain blood flow to the heart, brain stem, and placenta, is blunted by sympathectomy. Thus, the foetal sympatho-neuronal system is important for short-term adaptation to and intact survival of asphyxia.

Adaptation, Physiological↗
PubMed1992

Localization of human immunodeficiency virus core antigen in term human placentas.

Evidence of human immunodeficiency virus (HIV) replication was sought in human placentas obtained at term from pregnancies complicated by maternal HIV infection. Placentas were obtained from the pregnancies of 19 HIV-seropositive women, 4 women who were seronegative, and 4 untested women with no risk factors for HIV infection. These placentas were each examined by immunoperoxidase immunocytochemistry using monoclonal anti-p24/55 antibodies. In addition, minced placental tissue from 11 of the seropositive pregnancies and the 3 seronegative pregnancies were co-cultivated with stimulated human peripheral blood mononuclear cells. The clinical status of the infants born to the HIV-seropositive women was assessed when the infants were 8 to 28 months of age. P24/55 antigen was detected in 5 of the 19 placentas of the HIV-seropositive pregnancies and in none of the 8 placentas of seronegative or low-risk pregnancies. This HIV core viral antigen was located exclusively in the cytoplasm of villous cells with morphological characteristics of macrophages. The HIV antigen-containing cells were very sparsely distributed. Staining of the trophoblast was not observed in any placental specimen. Human immunodeficiency virus was isolated in culture from 3 of the 11 placentas from seropositive pregnancies. Clinical follow-up has not revealed a relationship between infection of the infant and either p24/55 antigen identification or isolation of virus from the placenta. Virological and histological evidence of HIV replication is found in approximately one fourth of placentas obtained at term from pregnancies complicated by maternal HIV infection. Replicating virus appears localized to sparse macrophages located within the chorionic villi, but specifically not within the trophoblastic layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1991

Regional brain blood flow and oxygen supply in guinea pig fetuses near term.

To examine brain blood flow and oxygen supply to 14 brain regions in fetal guinea pigs near term, 6 fetuses were catheterized under general anaesthesia of the dam between days 61 and 63 of pregnancy. Fetal arterial blood pressure was measured and a blood sample was taken from the right axillary artery to determine fetal blood gases and acid-base balance. Isotope-labelled microspheres were then injected in a lateral saphenous vein and a reference blood sample was taken from the right axillary artery according to Carter and Gu. Preductal arterial haemoglobin oxygen saturation ranged from 16-33% (26.7 +/- 6.3 mean +/- SD) and pH from 7.08-7.30 (7.20 +/- 0.09); oxygen content varied between 3.0-6.7 ml/dl. Blood flow to the whole brain was 105-258 ml/min per 100 g (167 +/- 58), oxygen supply to the brain was 6.6-10.7 ml O2/min per 100 g (8.0 +/- 1.6). Both regional brain blood flow and oxygen supply were significantly different in the various brain parts. They were highest in the spinal medulla and in other parts of the brain stem and lowest in the cerebrum. Brain blood flow increased significantly with increasing pCO2 and systolic blood pressure and with decreasing haemoglobin oxygen saturation, pH, base excess, and arterial oxygen content. On the other hand, except for the mid portion of the spinal medulla, there were no correlations between blood gas and acid-base balance variables and the oxygen supply to the whole brain or to various regions of the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The lentivirus regulatory proteins REV and REX are site specific RNA binding proteins.

These studies demonstrate that HIV-1 REV and HTLV-1 REX are site specific RNA binding proteins. In addition, the REV protein studies indicate a protein domain essential for biological function that is not involved in RRE binding. Lentiviruses are unique among retroviruses in providing gene products to switch expression from early to late genes. Rather than transcriptional control, this is accomplished by regulating RNA transport. A further understanding of these lentiviral genes may identify means of inhibiting viruses responsible for insidious human disease.

Amino Acid Sequence↗