Biomedical subjects

J Nielsen

Publications and source records attributed to J Nielsen.

At least 271 records · Page 15Linked to original sources

PubMed1993

[Merkel cell carcinoma].

Eight patients with Merkel cell carcinoma are reported to document their response to surgery and/or radiotherapy. Four patients who initially underwent surgery without postoperative radiation therapy all had local recurrence. Two patients were treated with postoperative radiation therapy and two were treated with radiation therapy without excision of the tumour. None of these four patients had local recurrence. Five patients developed regional recurrence. Recurrence was seen in one patient in the irradiated field. Metastatic disease was not seen in any case. These results combined with a review of the literature suggest that radiation therapy postoperatively to both the surgical bed and the draining lymph nodes may improve local regional tumour control.

Aged↗

PubMed1993

H-reflexes are less depressed following muscle stretch in spastic spinal cord injured patients than in healthy subjects.

The size of the soleus H-reflex was measured after a slow (17 deg/s) passive stretch of ankle plantarflexors and compared to its control size without muscle stretch in ten neurologically healthy subjects and in six spastic spinal-cord-injured patients. Two seconds after the end of the stretch, the size of the H-reflex was reduced to about 30% of its pre-stretch size in the healthy subjects. The depression remained for 10-15 s. In the spastic, spinal-cord-injured patients, stretch caused significantly less reduction in the size of the H-reflex. The H-reflex also regained its pre-stretch size much faster than in healthy subjects. We suggest that the smaller depression of the H-reflex observed in spastic patients may be involved in the pathophysiology of spasticity.

Adult↗

PubMed1993

Small airways function in aluminium and stainless steel welders.

The effect of welding fumes on small airways was studied in 25 male subjects who welded in aluminium (Al) and to some extent also in stainless steel (SS). Despite a low exposure to welding fumes as compared to the permissible exposure limits, excretion of Al in urine was found to be increased in all subjects (median value: 0.29 mmol/mol creatinine on Friday afternoon, as compared to an upper reference level of 0.10 mmol/mol creatinine). In addition, the welders displayed increased prevalences of work-related eye and airways (pharyngitis and non-specific bronchial hyperreactivity) symptoms, as compared to 25 matched controls. Short-term welders (< or = 2.5 years) had more symptoms related to the upper airways than did long-term welders, which may indicate a selection. Spirometry, closing volume and volume of trapped gas (VTG) did not deviate. However, after methacholine inhalation, the long-term welders had a significantly steeper slope of the alveolar plateau on the single-breath nitrogen wash-out test, and a slight increase in VTG, as compared to the short-term welders and the controls. These findings may indicate a welding fume-induced increase in the reactivity of the small airways. Because Al welding was far more frequent than SS welding, an association with the former seems likely.

Adult↗

PubMed1993

Infection studies with canine distemper virus in harbour seals.

Infection studies in harbour seal (Phoca vitulina) were conducted with the Snyder-Hill strain of canine distemper virus (CDV) that is virulent for dog and mink. The inoculated seals showed clinical symptoms which were to some degree similar to those observed in CDV infections of sensitive species of carnivores. Viral replication in lymphoid cells was followed by an extended period of immunosuppression. The results did not provide conclusive evidence for viral replication in surface epithelia of seals, and accordingly no spread of the infection to contact seals and mink was demonstrated. The pathogenicity of the infection did not increase upon a second viral passage in seal. The serological data showed that CDV-infected seals mounted an early virus specific antibody response. Overall, the results indicated that the harbour seal was not especially sensitive to CDV infection. The differences in the in vivo biological properties of CDV and PDV add to the distinction between these viruses at the genomic and antigenic levels.

Animals↗

PubMed1993

H-reflexes are smaller in dancers from The Royal Danish Ballet than in well-trained athletes.

The size of the maximal H-reflex (Hmax) was measured at rest and expressed as a percentage of the maximal M-response (Mmax) in 17 untrained subjects, 27 moderately trained subjects, 19 well-trained subjects and 7 dancers from the Royal Danish Ballet. The Hmax/Mmax was significantly larger in the moderately and well-trained subjects than in the untrained subjects but smaller in the ballet dancers. It is therefore suggested that both the amount and the type of habitual activity may influence the excitability of spinal reflexes.

Adolescent↗

PubMed1993

Evaluation of three transportable multigas anesthetic monitors: the Bruel & Kjaer Anesthetic Gas Monitor 1304, the Datex Capnomac Ultima, and the Nellcor N-2500.

We compared the performance of three newly developed anesthetic agent (AA) monitors: the Bruel & Kjaer Anesthetic Agent Monitor 1304 (BK 1304), the Datex Capnomac Ultima (ULTIMA), and the Nellcor N-2500 (N-2500). The following were investigated: the linearity and accuracy in measuring AAs, oxygen, carbon dioxide, and nitrous oxide; the linearity and accuracy during warm-up time; the effect of increasing respiratory rate on the accuracy; the consequences of a difference between monitored and delivered AA and of delivering a mixture of AAs; and, finally, the effect of water vapor and alcohol. For all three monitors we found that the accuracy in determining the respiratory and anesthetic gases was sufficient for clinical use (the N-2500 does not measure oxygen). Because of the calibration mixture supplied with the device, however, the ULTIMA recorded values that were 10 to 12% (relative) less than the AA that was present. The BK 1304 had greater accuracy at higher respiratory rates than did the other two monitors, probably favoring its use in pediatric anesthesia. The N-2500 will detect which agent (isoflurane, enflurane, or halothane) is being used, alone or in a mixture. With the two other monitors the user must define which agent is given. In some situations a difference between this and the one actually delivered can theoretically lead to an overdose of AA, with the ULTIMA up to a 14.9 minimal alveolar concentration (MAC) overdose. No interference from alcohol or water vapor in the expired air was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗

PubMed1993

Cyclothialidine and its congeners: a new class of DNA gyrase inhibitors.

Cyclothialidine is a new, potent DNA gyrase inhibitor isolated from Streptomyces filipinensis. However, it exhibits hardly any growth-inhibitory activity against intact bacterial cells. To explore its potential with regard to the development of a new type of antibacterial, a flexible synthetic route was worked out (i) to investigate the structural requirements for DNA gyrase inhibition and (ii) to search for congeners exerting antibacterial activity. The structure of cyclothialidine was confirmed by total synthesis. Marked DNA gyrase inhibitory activity was found for a number of analogs, a common feature of them being the bicyclic 12-membered lactone bearing one phenolic hydroxy group. Congeners of cyclothialidine were found to exhibit a moderate, but broad-spectrum, in vitro activity against Gram-positive bacteria. Therefore, the DNA gyrase inhibitory principle contained in cyclothialidine can be considered as the basis for a new class of antibacterial agents.

Anti-Bacterial Agents↗

PubMed1993

Induced astigmatism and its decay with a frown incision.

Forty consecutive patients selected for cataract extraction by phacoemulsification were studied to evaluate prospectively the amount of and changes in surgically induced astigmatism from a 5 mm to 6 mm pocket incision with the external opening made convex against the limbus (frown incision). All incisions had an internal corneal valve and were closed by a single X-stitch to counteract the relaxing effect of the pocket in the 90-degree meridian. Surgically induced astigmatism calculated by simple subtraction was 0.64 +/- 0.90 diopters (D) (P < .0001) on the first postoperative day, 0.03 +/- 0.58 D (P = .75) six weeks after surgery, and -0.18 +/- 0.44 D (P = .01) six months after surgery. Calculated from polar equivalents, the induced astigmatism on the first postoperative day was 0.98 D +/- 1.03 D (P = .0001), after six weeks -0.11 D +/- 0.64 D (P = .30), and after six months -0.28 D +/- 0.49 D (P = .0009). On the first postoperative day 42% of eyes had less than 0.5 D of induced astigmatism, 68% had less than 1.0 D, and 79% had less than 1.5 D. After six weeks the respective percentages increased to 61%, 97%, and 97% and after six months to 84%, 100%, and 100%. The distribution of patients with against-the-rule, oblique, and with-the-rule astigmatism preoperatively was nine, 20, and 11, respectively, and 11, 19, and nine after six months. The amount of astigmatism induced from the 5 mm to 6 mm frown incision did not differ from that found in previously published studies of smaller incisions (to about 4 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Accuracy of 94 anaesthetic agent vaporizers in clinical use.

Using the Brüel & Kjaer Anaesthetic Gas Monitor type 1304, we have monitored the output of 94 anaesthetic agent vaporizers (Fluotec 3:58, Enfluratec 3:24, Isotec 3:12), in seven departments of anaesthesia, at different dial settings and flow rates. The range of output, for one type of vaporizer and dial setting (flow: 6 litre min-1) was largest with the Fluotec 3 (0.85-1.55% when dial set to 1%) and smallest with the Isotec 3 (0.85-1.15% when dial set to 1%). In determining the number of vaporizers with unacceptable inaccuracy, we applied acceptance limits of +/- 15% relative on each vaporizer and each dial setting. Using a flow of oxygen 6 litre min-1 17% of Fluotec 3.8% of Isotec 3 and 71% of Enfluratec 3 vaporizers had outputs outside those limits. Even when some specific conditions (vaporizers giving output beyond the limits at any two or more dial settings; output beyond the limits in the clinically relevant range (0.5-2%)) were added, a substantial number of vaporizers did not perform within the limits. We found a significantly greater accuracy of the vaporizers after 3-monthly calibration checks (P < 0.05) compared with vaporizers undergoing service and calibration only annually. Using a questionnaire, we found that fewer than 30% of the anaesthetists using the vaporizers would accept aberrance beyond +/- 10% relative of the dial setting.

Anesthesia, Inhalation↗

PubMed1993

Does exercise-induced ST-segment depression predict benefit of medical intervention in patients recovering from acute myocardial infarction? The Danish Study Group on Verapamil in Myocardial Infarction.

The present study tested the hypothesis that the increased risk in patients with exercise-provoked ST-segment depression recovering from acute myocardial infarction could by abolished by anti-ischaemic medical intervention. Prior to discharge a symptom-limited exercise test was carried out. Patients were then double-blindly randomized to treatment with either verapamil 120 mg t.i.d. or placebo, and observed for up to 18 months (mean 17 months). End-point was first major event; i.e. non-fatal reinfarction or death. Two-hundred-and-ninety-eight patients were included. Forty-four patients with and 111 without exercise-induced ischaemia were randomized to verapamil and 39 and 104 respectively, to placebo. The overall number of events was 12.5%. In patients without ST-segment depression, 12.5% in the placebo group (hazard = 1) and 12.6% in the verapamil group (hazard = 1.13) had an event (NS). In patients with ST-segment depression 15.4% in the placebo group (hazard = 1.20) and 9.1% in the verapamil group (hazard = 0.85) had an event (NS). The latter reduction (41%) supports the hypothesis that patients with ST-segment depression, i.e. residual myocardial ischaemia, are those who benefit from anti-ischaemic intervention after myocardial infarction.

Aged↗

PubMed1993

Psychomimetic reactions after neurolept and propofol anaesthesia.

The purpose of this study was to compare the frequency of psychomimetic reactions after 24 h and 3 months following total intravenous anaesthesia with propofol and neurolept anaesthesia. Forty otherwise healthy female patients were randomly divided into two groups. All were undergoing elective gynaecological laparotomy for non-malignant disease. Nineteen patients were anaesthetized with droperidol, fentanyl, pancuronium, N2O/O2. Twenty patients received total intravenous anaesthesia with propofol, fentanyl and pancuronium. Twenty-four hours after the anaesthesia the patients were interviewed about their subjective experiences of anaesthesia and recovery. Three months after the operation the patients were sent a questionnaire concerning ability to work, sleep and memory disorders. After 24 h the anaesthesia was judged as good by 18 patients receiving propofol and 13 patients receiving NLA (n.s.). The recovery was judged as good by 16 patients in the propofol group and six patients in the NLA group (P < 0.05). Locked-in feelings were reported by one patient in the propofol group and ten patients in the NLA group (P < 0.01). Impairment of memory was reported by one patient in the propofol group and seven patients in the NLA group (P < 0.01). A questionnaire used after 3 months was answered by 18 patients in the propofol group and 17 patients in the NLA group. There were few complaints, and no differences were found between the two groups. In conclusion, total intravenous anaesthesia with propofol seems more acceptable than anaesthesia with neurolept as judged by the patients 24 h after anaesthesia. There were no differences between the two groups concerning psychomimetic reactions 3 months after anaesthesia.

Adult↗

PubMed1993

Low-flow isoflurane-nitrous oxide anaesthesia offers substantial economic advantages over high- and medium-flow isoflurane-nitrous oxide anaesthesia.

Isoflurane consumption was studied for three different fresh gas flows in patients scheduled for major elective abdominal, urological or gynaecological surgery under general anaesthesia with an expected duration of 2 h or more. Thirty patients were randomly assigned to either high-flow anaesthesia using a partial rebreathing system without carbon dioxide absorption (Mapleson D) or medium- or low-flow anaesthesia using a circle system with carbon dioxide absorption. Patients were anaesthetised with isoflurane in 40% oxygen and 60% nitrous oxide. The amount of isoflurane consumed was measured with a precision scale. The total consumption of liquid isoflurane (mean +/- s.d.) during the first 2 h was 40.8 +/- 12.2 ml in the high-flow group, 18.5 +/- 5.4 ml in the medium-flow group and 7.9 +/- 2.2 ml in the low-flow group. The corresponding cost of isoflurane for the three groups was 214 Danish kroner (DKK) (19.5 pounds), 97 DKK (8.8 pounds) and 42 DKK (3.8 pounds), respectively. The calculated total cost of anaesthetics was 286 DKK (26 pounds), 155 DKK (14.1 pounds) and 91 DKK (8.3 pounds), respectively. In conclusion, low-flow isoflurane-nitrous oxide anaesthesia offers substantial economic advantages over high- and medium-flow isoflurane-nitrous oxide anaesthesia.

Adult↗

PubMed1993

Differential projection of the sural nerve to early and late recruited human tibialis anterior motor units: change of recruitment gain.

The effect of a stimulation of the cutaneous sural nerve [three shocks, 2.5 x perception threshold (PT)] was studied on the tibialis anterior (TA) H-reflex and single voluntarily activated TA motor units using post-stimulus time histograms (PSTH). In both cases, when studying only the first recruited motor units, an inhibition with a delay of 10 ms, in relation to the monosynaptic latency of Ia afferents in the common peroneal nerve, was observed. This inhibition had a duration of 10-20 ms. The inhibition was evoked by low-threshold cutaneous fibres, since it could be seen at a stimulation strength close to the perception threshold. The central delay of the inhibition was calculated in two subjects to be 1.8 ms and 1.2 ms respectively. The TA motor units were characterized by their recruitment threshold and minimal firing frequency and the effect of the sural nerve stimulation was subsequently investigated. Early recruited low frequency motor units were found to be inhibited, whereas later recruited motor units with a higher minimal firing frequency were facilitated. Similarly small TA H-reflexes were inhibited, whereas large reflexes were facilitated. This difference in the effect of the sural nerve stimulation was not caused by a difference in the descending command, since the same early recruited motor unit was still inhibited when firing at a high frequency and at a high torque level. Stimulation of the femoral nerve was found to produce a monosynaptic facilitation of the TA H-reflex and a heteronymous monosynaptic peak in the PSTH of single motor units. A stimulation of the sural nerve increased the size of the reflex facilitation, but had no effect on the size of the monosynaptic peak in the PSTH of the single motor units. It is concluded that the effect of the sural nerve stimulation on human TA motor units is similar to observations in the cat and that a similar interneuronal system may be responsible. It is furthermore suggested that the sural nerve stimulation increases the recruitment gain of the TA motoneuronal pool.

Adult↗

PubMed1993

The regulation of presynaptic inhibition during co-contraction of antagonistic muscles in man.

1. The size of the soleus, tibialis anterior and medial gastrocnemius H reflexes were measured at different levels of EMG activity in ankle plantar- and dorsiflexors. At similar levels of EMG activity in the agonist muscle, the soleus and tibials anterior H reflexes were found to be smaller during co-contraction than during an isolated agonist contraction. In contrast to this, the medial gastrocnemius H reflex had the same size during co-contraction as during an isolated plantarflexion at comparable EMG levels. 2. Peaks occurred at monosynaptic reflex latency in the post-stimulus time histogram (PSTH) of firing of soleus and tibialis anterior motor units following stimulation of their respective motor nerves. These homonymous Ia peaks were found to be smaller during co-contraction than during isolated agonist contraction, whereas that of medial gastrocnemius motor units was unchanged. As the monosynaptic peak in the PSTH may give an indirect measure of the size of the monosynaptic EPSP in the motoneurone, it is suggested that these findings reflect a differential control of presynaptic inhibition of soleus and tibialis anterior motor units with respect to medial gastrocnemius motor units. 3. The monosynaptic Ia facilitation of the soleus H reflex evoked by a stimulation of the femoral nerve, was also found to be smaller during co-contraction of tibials anterior and soleus than during isolated plantarflexion. This suggests that presynaptic inhibition of heteronymous Ia fibres from the quadriceps muscle projecting to soleus motoneurones is regulated in the same way as presynaptic inhibition of homonymous Ia fibres during co-contraction. 4. The femoral nerve-induced monosynaptic facilitation of the soleus H reflex was found to decrease with increasing tonic levels of both co-contraction and isolated dorsi- and plantarflexion. The amount of facilitation decreased to the same degree with increasing levels of dorsiflexion and co-contraction. For the same level of EMG in the dorsiflexors there was thus no difference in the amount of facilitation whether the dorsiflexors were activated separately or in a co-contraction. 5. Whereas the soleus H reflex increased in size 50 ms prior to the onset of a dynamic plantarflexion, it did not change prior to the onset of a co-contraction. The femoral nerve-induced facilitation increased prior to the plantarflexion, but decreased prior to the co-contraction.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1993

Task-related changes in the effect of magnetic brain stimulation on spinal neurones in man.

1. The effect of magnetic stimulation of the human motor cortex on the excitability of soleus, tibialis anterior and flexor carpi radialis motoneurones was investigated by H reflex testing in ten healthy subjects. 2. At rest, an early facilitation of the flexor capri radialis and tibialis anterior H reflexes was always seen, whereas a similar early facilitation of the soleus H reflex was seen in only two out of seven subjects. For all three motoneuronal pools the facilitation was curtailed 1-5 ms later by an inhibition which lasted for another 3-4 ms. In five subjects an inhibition without any evidence of an earlier facilitation was seen for the soleus H reflex. 3. The intensity of the magnetic stimulation was subsequently decreased so that it had no effect on the H reflex at rest. When the subject then performed a voluntary agonist contraction a facilitatory effect with an early onset and a duration of 20-25 ms was observed for all three muscles. When the subject performed a voluntary antagonist contraction an inhibition was seen for the soleus H reflex with an onset 1-3 ms later than the facilitation. This is interpreted as resulting from the excitation by the magnetic stimulus of corticospinal neurones voluntarily activated in relation to the given motor task. 4. The initial part of the facilitation was significantly smaller during co-contraction of both agonists and antagonists than during isolated agonist contraction. 5. Whereas the early part of the facilitation always occurred during plantarflexion when the H reflex was conditioned by magnetic stimulation, this was never the case when it was conditioned by electrical stimulation of the cortex with the stimulus regimes used in these experiments. 6. It is suggested that the early part of the facilitation observed during agonist contraction is caused by activation of cortico-motoneuronal cells projecting to the agonist motoneuronal pool and that the inhibition observed during antagonist contraction is caused by activation of corticospinal cells projecting both to the antagonist motoneuronal pool and Ia inhibitory interneurones to the agonist motoneuronal pool. The smaller size of the earliest part of the facilitation observed during co-contraction in relation to agonist contraction suggests a different cortical control of the two tasks.

Adult↗

PubMed1993

Two Uptake Systems for Fructose in Lactococcus lactis subsp. cremoris FD1 Produce Glycolytic and Gluconeogenic Fructose Phosphates and Induce Oscillations in Growth and Lactic Acid Formation.

Fructose transport in lactococci is mediated by two phosphotransferase systems (PTS). The constitutive mannose PTS has a broad specificity and may be used for uptake of fructose with a fructose saturation constant (K(Fru)) of 0.89 mM, giving intracellular fructose 6-phosphate. The inducible fructose PTS has a very small saturation constant (K(Fru), <17 muM), and the fructose 1-phosphate produced enters the Embden-Meyerhof-Parnas (EMP) pathway as fructose 1,6-diphosphate. Growth in batch cultures of Lactococcus lactis subsp. cremoris FD1 in a yeast extract medium with fructose as the only sugar is poor both with respect to specific growth rate and biomass yield, whereas the specific lactic acid production rate is higher than those in similar fermentations on other sugars metabolized via the EMP pathway, e.g., glucose. In fructose-limited chemostat cultures, the biomass concentration exhibits a strong correlation with the dilution rate, and starting a continuous culture at the end of a batch fermentation leads to large and persistent oscillations in the biomass concentration and specific lactic acid production rate. Two proposed mechanisms underlying this strange growth pattern follow. (i) Fructose transported via the fructose PTS cannot be converted into essential biomass precursors (glucose 6-phosphate or fructose 6-phosphate), because L. lactis subsp. cremoris FD1 is devoid of fructose 1,6-diphosphatase activity. (ii) The fructose PTS apparently produces a metabolite (presumably fructose 1-phosphate) which exerts catabolite repression of both mannose PTS and lactose PTS. Since the repressed mannose PTS and lactose PTS are shown to have identical maximum molar transport rates, the results indicate that it is the general PTS proteins which are repressed.

Journal Article↗

PubMed1993

Doxazosin treatment in patients with prostatic obstruction. A double-blind placebo-controlled study.

The safety and efficacy of the selective alpha 1-blocking agent doxazosin 4 mg once daily in the symptomatic treatment of benign prostatic hyperplasia were evaluated in a randomized, double-blind and placebo-controlled 9-week study of 100 patients. By patients' overall assessment of voiding difficulties, 79% in the doxazosin group (DG) and 44% in the placebo group (PG) reported improvement (p = 0.001). In the DG, improvement was noted in 63% of obstructive symptoms compared to 32% in the PG (p = 0.015), whereas improvement was noted in 76% and 45%, respectively, of irritative symptoms (p = 0.12). Daytime frequency was reduced by 1.5 in the DG and increased by 0.3 in the PG (p = 0.001), and nocturia was reduced by 1.1 and 1.0, respectively (p = 0.12). Maximum urinary flow rate was improved by 1.5 ml/s in the DG, while it deteriorated by 0.3 ml/s in the PG (p = 0.11). Considering postvoid residual urine volume, cystometry variables (first sensation and bladder capacity) and adverse events there was no difference between the two groups. In conclusion, doxazosin 4 mg once daily is safe and effective in relieving symptoms in patients with BPH.

Aged↗

PubMed1992

[Treatment of girls with Turner's syndrome with growth hormone and estrogen--1-year experiences].

Girls with Turner's syndrome are characterized by growth retardation and defective pubertal development, among other features. In this investigation, 40 girls with Turner's syndrome were treated with growth hormone in doses of 0.1 IU/kg/day (group 1, n = 14), oral oestradiol in doses of 0.01 mg/kg/day (group 2, n = 8) or a combination of these (group 3, n = 18), depending on the bone age. All three forms of treatment increased the height velocity significantly. The combined treatment increased the height velocity more than the growth hormone of oestradiol alone (p less than 0.05). In group 2, a pronounced progression of bone age leading to a decrease in the prognosis of final height was observed. The serum insulin-like growth factor I was unchanged in group 2 while this rose in groups 1 and 3. Pubertal development was, by and large, satisfactory. No serious side effects were observed. Treatment of girls with Turner's syndrome with growth hormone should not be supplemented with oestrogen prior to the bone age of 11 years. The initial dosage of oestradiol should be less than 0.01 mg/kg/day, but the subsequent increase should be adjusted individually.

Adolescent↗