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Biomedical subjects

B L Nielsen

Publications and source records attributed to B L Nielsen.

At least 19 recordsLinked to original sources
PubMed1991

Pea chloroplast DNA primase: characterization and role in initiation of replication.

A DNA primase activity was isolated from pea chloroplasts and examined for its role in replication. The DNA primase activity was separated from the majority of the chloroplast RNA polymerase activity by linear salt gradient elution from a DEAE-cellulose column, and the two enzyme activities were separately purified through heparin-Sepharose columns. The primase activity was not inhibited by tagetitoxin, a specific inhibitor of chloroplast RNA polymerase, or by polyclonal antibodies prepared against purified pea chloroplast RNA polymerase, while the RNA polymerase activity was inhibited completely by either tagetitoxin or the polyclonal antibodies. The DNA primase activity was capable of priming DNA replication on single-stranded templates including poly(dT), poly(dC), M13mp19, and M13mp19 + 2.1, which contains the AT-rich pea chloroplast origin of replication. The RNA polymerase fraction was incapable of supporting incorporation of 3H-TTP in in vitro replication reactions using any of these single-stranded DNA templates. Glycerol gradient analysis indicated that the pea chloroplast DNA primase (115-120 kDa) separated from the pea chloroplast DNA polymerase (90 kDa), but is much smaller than chloroplast RNA polymerase. Because of these differences in size, template specificity, sensitivity to inhibitors, and elution characteristics, it is clear that the pea chloroplast DNA primase is an distinct enzyme form RNA polymerase. In vitro replication activity using the DNA primase fraction required all four rNTPs for optimum activity. The chloroplast DNA primase was capable of priming DNA replication activity on any single-stranded M13 template, but shows a strong preference for M13mp19 + 2.1. Primers synthesized using M13mp19 + 2.1 are resistant to DNase I, and range in size from 4 to about 60 nucleotides.

Antibodies↗
PubMed1990

Transient foreign gene expression in chloroplasts of cultured tobacco cells after biolistic delivery of chloroplast vectors.

Expression of chloramphenicol acetyltransferase (cat) by suitable vectors in chloroplasts of cultured tobacco cells, delivered by high-velocity microprojectiles, is reported here. Several chloroplast expression vectors containing bacterial cat genes, placed under the control of either psbA promoter region from pea (pHD series) or rbcL promoter region from maize (pAC series) have been used in this study. In addition, chloroplast expression vectors containing replicon fragments from pea, tobacco, or maize chloroplast DNA have also been tested for efficiency and duration of cat expression in chloroplasts of tobacco cells. Cultured NT1 tobacco cells collected on filter papers were bombarded with tungsten particles coated with pUC118 (negative control), 35S-CAT (nuclear expression vector), pHD312 (repliconless chloroplast expression vector), and pHD407, pACp18, and pACp19 (chloroplast expression vectors with replicon). Sonic extracts of cells bombarded with pUC118 showed no detectable cat activity in the autoradiograms. Nuclear expression of cat reached two-thirds of the maximal 48 hr after bombardment and the maximal at 72 hr. Cells bombarded with chloroplast expression vectors showed a low level of expression until 48 hr of incubation. A dramatic increase in the expression of cat was observed 24 hr after the addition of fresh medium to cultured cells in samples bombarded with pHD407; the repliconless vector pHD312 showed about 50% of this maximal activity. The expression of nuclear cat and the repliconless chloroplast vector decreased after 72 hr, but a high level of chloroplast cat expression was maintained in cells bombarded with pHD407. Organelle-specific expression of cat in appropriate compartments was checked by introducing various plasmid constructions into tobacco protoplasts by electroporation. Although the nuclear expression vector 35S-CAT showed expression of cat, no activity was observed with any chloroplast vectors.

Cells, Cultured↗
PubMed1989

[Treatment of acute myocardial infarction--an elucidative report].

The present-day optimal treatment of patients with acute myocardial infarction (AMI) is reviewed. The prehospital phase should be as brief as possible. Emergency observation and treatment in hospital should be initiated without delay. Schematic stages for mobilization have been discarded and free mobilization is recommended. Routine acute intervention with thrombolysis is recommended for patients in whom symptoms have been present for 6-12 hours and treatment with Aspirin is recommended. Beta-blocking agents are recommended for patients with increased risk after discharge. Treatment of ventricular and supraventricular arrhythmias, block and cardiac failure are reviewed in detail. Patients without complications should be monitored for three to five days and may be discharged after seven to ten days. Exercise ECG should be carried out at discharge to assess the working capacity, ischaemia and subjective reaction. The importance of good patient information is emphasized. Cessation of smoking, control of lipids and blood pressure are important as secondary interventions. As far as possible, outpatient control should be offered after discharge. The criteria for referral to specialized cardiological departments are established both for emergency and elective referral. Patients under the age of 70 years with high risk for repeated AMI or death after discharge (with residual ischaemia) should possibly be referred for coronary arteriography.

Adrenergic beta-Antagonists↗
PubMed1989

Subjective consequences of permanent pacemaker therapy in patients under the age of retirement.

During a 5-year period, 81 patients ages 20 to 60 years old had implantation of a permanent cardiac pacemaker at the University Hospital, Odense. At follow-up, during 1985, the 73 survivors received a semi-structured questionnaire regarding subjective consequences of pacemaker therapy, and 72 people (98.6%) agreed to participate. The mean pacing period (range) was 33.8 (11-72) months. Surgical intervention was required in 14 patients (19.4%) during follow-up. Regarding all symptoms 67 patients (93.1%) perceived benefit from the pacemaker. The effectiveness of cardiac pacing was most pronounced in subjects suffering from syncope and/or dizziness. Eight patients (11.1%) perceived anxiety most frequently due to fear of pacing failure. Physical complaints were present in 17 patients (23.6%), and the discomfort was mainly due to the size of generator, pain/tenderness from the scar or a sensation of "impulses"/palpitations. To the majority (49 patients or 68.1%) pacemaker treatment did not influence quality of sexual activity. Six patients (8.3%) perceived an improvement, whereas a corresponding number felt deterioration in sexual activity following pacemaker implantation. Pacemaker therapy had not affected life quality in 30 (41.7%) of the patients. However 31 patients (43%) felt an improvement, and only a minority of ten patients (13.9%) perceived deterioration in quality of life owed to pacemaker therapy.

Adult↗
PubMed1985

Purification and subunit characterization of Rhizobium meliloti RNA polymerase.

The RNA polymerase of the symbiotic, nitrogen-fixing bacterium Rhizobium meliloti was purified, and its subunit composition was determined. The cells were disrupted in the presence of protease inhibitors, and holoenzyme fractions were purified by fractionation by using DEAE-cellulose and DNA-agarose chromatography. The core polymerase was purified by additional chromatography on phosphocellulose. The subunit structure is beta prime (155,000 molecular weight), beta (151,000), alpha (43,000), and sigma (93,000), with an additional polypeptide of 29,000 molecular weight, which we have designated tau, found associated with both core and holoenzyme fractions. The measured stoichiometry of the holoenzyme complex was found to be 2 alpha:1 beta':1 beta:0.7 sigma:1 tau. The 93,000 molecular-weight protein subunit was identified as the sigma subunit based upon stimulation of specific transcription in assays with reconstituted polymerase.

DNA-Directed RNA Polymerases↗
PubMed1979

'alpha pattern coma' following cerebral anoxia.

In 30 patients, who were all comatose as a result of cerebral anoxia after cardiac arrest, at least one EEG with activity in the alpha frequency range was recorded. Regionally the activity of the above mentioned characteristic was often diffusely distributed or most pronounced occipitally, whereas a tendency to affect other regions was rarely observed. In 50% of the patients, where more than one EEG was recorded, the 'alpha' rhythm was still present in the following record. Only one of the patients survived, and even so, with considerable mental defects. In 4 patients the level of consciousness improved, but 3 of them never reached a definite level of cortical function and died as a result of cerebral anoxia.

Adult↗
PubMed1978

Electroencephalographic prediction of anoxic brain damage after resuscitation from cardiac arrest in patients with acute myocardial infarction.

The short-term prognostic value of routine electroencephalography (EEG), carried out on the days after cardiac arrest, was evaluated in a consecutive study of 185 patients with acute myocardial infarction together with an episode of clinical cardiac arrest. The individual EEGs were classified on a 5-grade scale. Of the 89 patients who survived, 18 had signs of anoxic brain damage; 96 patients died, 76 as a result of cerebral anoxia. Only 2 patients survived out of the total of 72 for whom the first EEG was classified as grades III--V. The EEGs of both these patients were recorded within a few hours after the cardiac arrest. None of the patients with an EEG of grade I died of cerebral anoxia, while all degrees of brain damage were otherwise observed in connection with EEGs of both grades I and II. It is concluded that an EEG of grades III--V indicates a fatal outcome, provided it has been recorded more than 24 hours after the cardiac arrest. A grade III--V EEG that is recorded within 24 hours after a cardiac arrest should be repeated some days later. It is not possible, on the basis of a single EEG, to predict the extent of the anoxic brain damage.

Acute Disease↗