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Biomedical subjects

H C Hansen

Publications and source records attributed to H C Hansen.

54 records · Page 3Linked to original sources
PubMed1996

Sensory deficits of a nerve root lesion can be objectively documented by somatosensory evoked potentials elicited by painful infrared laser stimulations: a case study.

Somatosensory evoked potentials (SEPs) in response to painful laser stimuli were measured in a patient with a unilateral sensory deficit due to radiculopathy at cervical levels C7 and C8. Laser evoked potentials (LEPs) were compared with SEPs using standard electrical stimulation of median and ulnar nerves at the wrist and mechanical stimulation of the fingertips by means of a mechanical stimulator. Early and late ulnar and median nerve SEPs were normal. Mechanical stimulation resulted in w shaped early SEPs from all five fingertips with some degree of abnormality at the fourth and fifth digits of the affected hand. Late LEPs were completely absent for stimulations at affected dermatomes and normal in the unaffected control dermatomes. The border between skin areas with normal or absent LEPs was very sharp and fitted the dermatomes of intact C6 and damaged C7 and C8 nerve roots. It is suggested that pain dermatomes are narrower than tactile dermatomes because thin fibres of the nociceptive system, activated by laser stimuli, probably do not overlap between adjacent spinal segments to the same extent as thick fibres of the mechanoreceptive system, activated by standard electrical or mechanical stimulation.

Aged↗
PubMed1996

Visually evoked cerebral blood flow velocity changes in different states of brain dysfunction.

BACKGROUND AND PURPOSE: By assessment of metabolically induced cerebral blood flow velocity changes, transcranial Doppler sonography offers the opportunity to evaluate vasoneuronal coupling in different states of brain activation and in critically ill patients. METHODS: With simultaneous transcranial Doppler monitoring of the posterior cerebral artery (PCA) and the middle cerebral artery (MCA), 27 control subjects, 11 patients under general anesthesia, 5 patients in the vegetative state, and 12 patients with aneurysmal subarachnoid hemorrhage were stimulated with a 10-Hz flashlight for 30 seconds. Ten cycles of stimulation were averaged, and a specific flow response (SFR) was computed as the normalized ratio of PCA/MCA mean flow velocity. RESULTS: Maximal SFR was 14.2% in control subjects. Eye closure significantly reduced maximal SFR (11.6% versus 15.4%, P<.01). In subarachnoid hemorrhage, SFR was markedly decreased in the early phase (4.8%, P<.01) but became normal later on. Four of 5 patients with abolished SFR suffered delayed ischemia due to vasospasm. Of 7 patients with preserved SFR, 5 had vasospasm but none had delayed ischemia. No SFR was observed in patients under general anesthesia or in the vegetative state. CONCLUSIONS: Although reflecting fast and local neuronal activity patterns, metabolically induced blood flow response is highly dependent on stimulus-directed attention. In subarachnoid hemorrhage, decreased metabolic flow response suggests severe depression of vasoneuronal coupling, and abolished SFR might indicate increased vulnerability to vasospasm and a higher risk for delayed ischemia.

Adult↗
PubMed1996

Reversible dementia in idiopathic hypoparathyroidism associated with normocalcemia.

Dementia in idiopathic hypoparathyroidism is generally ascribed to hypocalcemia and improves following normalization of the serum calcium level. We report a 51-year-old man with severe dementia and hypoparathyroidism, but without serum hypocalcemia and without clinical signs of hypocalcemia. There was rapid and sustained improvement and normalization of symptoms after therapy with 1,25-dihydroxy-cholecalciferol. We conclude that hypocalcemia is not the sole cause of dementia in idiopathic hypoparathyroidism.

Calcium↗
PubMed1995

Characterization of novel ligands for wild-type and natural mutant diazepam-insensitive benzodiazepine receptors.

A series of benzodiazepine receptor ligands with different chemical structures were evaluated for their affinities at diazepam-sensitive and diazepam-insensitive binding sites for [3H]Ro 15-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo-[1,5a][1,4] benzodiazepine-3-carboxylate) in cerebellar GABAA receptors. Rats of Wistar strain and of alcohol-sensitive (ANT) and alcohol-insensitive (AT) lines were used. The ANT rats possess a single point mutation in their GABAA receptor alpha 6 subunit, which makes their diazepam-insensitive sites sensitive to benzodiazepine agonists, unlike those of AT and Wistar rats. All compounds evaluated displayed high-affinity binding to diazepam-sensitive sites (Ki < 50 nM). In contrast, a wider range of affinities were observed at diazepam-insensitive sites which depended upon the basic structure and substitutions. The 7- and 8-halogen substituted imidazobenzodiazepines and 12-halogen substituted diimidazoquinazolines displayed the highest affinities (Ki < 15 nM), while intermediate to low affinities (100 < Ki < 4000 nM) were displayed by imidazoquinazolines, thienopyrimidines, one oxoimidazoquinoxaline, and some cyclopyrrolones. The imidazoquinoxalines evaluated displayed the lowest affinity (Ki > 10000 nM). The oxoimidazoquinoxaline, 6-chloro-3-(5-cyclopropyl-1,2,4-oxadiazol-3-yl)-4,5-dihydro-5-isop ropyl-4-oxo-imidazo[1,5-a]quinoxaline (NNC 14-0578) and suriclone represent the first benzodiazepine receptor full agonists to bind with relatively high affinity (Ki approximately 100 nM) to diazepam-insensitive sites. The 5 position substituted methoxybenzyl, dimethylallyl, and 4-fluorobenzyl oxoimidazoquinoxaline analogs demonstrated a 58-336-fold higher affinity for ANT than AT diazepam-insensitive sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The characterization of Danish isolates of Salmonella enterica serovar Enteritidis by phage typing and plasmid profiling: 1980-1990.

Plasmid profiling, phage typing and antimicrobial resistance typing have been carried out on 736 isolates of Salmonella enterica serovar Enteritidis collected in Denmark during the period 1980 to 1990. Strains originated from cases of human salmonellosis, broiler poultry flocks, layer poultry flocks, quarantined imported poultry, environmental samples from hatchery units, and from bovines. Phage type (PT) 1 was found to be the most common type among isolates of poultry origin (57.6%) followed by PT4 (28.8%). Isolates belonging to PT8 were found exclusively in imported birds. Phage typing of a representative sample of human isolates revealed the predominance, as in most other Western European countries, of PT4 (61.8%). PT1, however, was found in 17.0% of human strains, a much higher incidence than expected. Antibiotic resistance was observed in 4 out of 107 human isolates (3.7%) and 2 out of 205 non-human isolates (1%) tested.

Animals↗
PubMed1992

Differential potentiation of GABAA receptor function by two stereoisomers of diimidazoquinazoline analogues.

1. U-84935, diimidazo[1,5-a;1',2'-C]quinazoline,5-(5-cyclopropyl-1,2,4-oxid iazol-3yl)- 2,3-dihydro, is a ligand of high affinity for the benzodiazepine site of the GABAA receptor composed of alpha 1 beta 2 gamma 2 subunits. 2. The efficacy of its analogues was measured with their ability to potentiate GABA-mediated Cl- currents in the whole cell configuration of the patch clamp techniques in human kidney cells (A293 cells) expressing the subtype of the GABAA receptor. 3. The analogues displayed various levels of efficacy including agonists, partial agonists and antagonists without marked changes in their affinity for the receptors. 4. The major determinant of their efficacy was the spacial configuration of a methyl substituent of the C2 atom of the rigid and planar diimidazoquinazoline ring: U-90167, containing the methyl substituent projected below the plane of the ring, markedly enhanced the GABA current with a maximal potentiation of 220 +/- 25%, while its stereoisomer, U-90168, marginally increased the GABA response with a maximal potentiation of 45 +/- 10%, to which its methyl group appeared to contribute very little. 5. U-90167 potentiated the GABA response with an EC50 of 8.1 nM and a Hill coefficient of 1.1 and did not alter the reversal potential for the Cl- current. 6. From computational modelling, the sensitive methyl group of U-90167 could be assigned to the general region for the 5-phenyl group of diazepam. The diimidazoquinazoline, because of its rigid and plantar ring structure, may be useful to define further the out-of-plane region responsible for agonistic activity and to pinpoint other areas pivotal to the functionality of benzodiazepine ligands.

Binding Sites↗
PubMed1991

Increase in saccadic peak velocity with increased frequency of saccades in man.

Twelve normal subjects (aged 22-80 yr, mean 47 yr) performed three blocks of 20 saccades made to LED targets stepped back and forth. The first and last blocks were performed at a (slow) rate of 0.18 Hz, while the middle block was performed at the faster rate of 1.15 Hz. Mean saccadic amplitude was unaffected by saccade rate, but latency and duration became shorter at the higher frequency. Most interestingly, the peak velocity increased by approx. 6% when saccades were performed at the higher rate. This increase was statistically significant, even after normalization for saccade amplitude. That saccadic frequency may affect saccadic peak velocity must be considered as a potential variable when analysing saccades.

Adult↗
PubMed1991

Plasmid profiles of Salmonella enterica serovar berta isolated from broilers in Denmark.

Salmonella enterica serovar berta was isolated for the first time in Denmark in October 1984. This serovar has subsequently become endemic in the broiler industry. Plasmid profile analysis of 610 strains of S. berta isolated from broilers and broiler parent stock in the period October 1984 to July 1989 showed that plasmids were present in 85.7% of strains investigated, with a mean of 1.8 plasmids per strain. A significant increase in the mean number of plasmids per strain was seen during the observation period. Seventeen different plasmid sizes and 90 different plasmid profiles were identified. Plasmid profiling of S. berta appears to represent a promising tool for analysing the epidemiology of S. berta infections in broilers.

Animals↗
PubMed1991

Loss of nitroglycerin during passage through two different infusion sets.

The loss of nitroglycerin (GTN) during passage through a polyvinyl chloride (PVC) or polyethylene (PE) infusion set was investigated. The GTN concentration had no influence on the GTN loss in the PVC set. The study confirmed reports in the literature that the greatest loss of GTN occurs at the slowest rate of infusion. Interestingly, the lowest concentration of GTN is seen when the volume equivalent to the capacity of the infusion set has passed through the set. When we simulated the procedure recommended by the health authorities in Norway and Sweden, we observed a loss of up to 70% during infusion through the PVC set in the first 30 minutes, which decreased to 30% over the next seven hours. The loss from the PE set did not exceed 15% over eight hours.

Infusions, Intravenous↗
PubMed1990

Cerebral potentials evoked by fast head accelerations.

Fast, time optimal, voluntary horizontal head rotations produce evoked cerebral potentials (EPs). These show distinct amplitudes between 10 and 25 microV and latencies of N1 66 ms, N2 178 ms, P1 295 ms and N3 424 ms. Specifically, an increase in head acceleration is significantly correlated with a decrease of the latency of the EPs and an increase in their normalized amplitude. Control studies with isolated proprioceptive stimulation of the wrists and the neck with the head fixed provided evidence for the dominant vestibular generation of the head movement associated EP that is fine tuned throughout changes in head acceleration.

Acceleration↗
PubMed1989

[Bruising after venepuncture].

A randomized cross-over investigation was carried out on 24 healthy volunteers to investigate the occurrence of bruising following compression on the extended or flexed elbow respectively, following venepuncture in the cubital fossa. Following 48 uncomplicated venepunctures (24 x 2) a total of 8 (17%) were found to have bruising, four of these after compression on the extended elbow and four after compression on the flexed elbow. It is concluded that there are no differences in the frequencies of bruising following closed venepuncture in the cubital fossa regardless of whether the subsequent compression is undertaken on the extended or flexed elbow.

Adult↗
PubMed1989

Local irritation after administration of diazepam in a rectal solution.

The extent of local irritation after rectal administration of diazepam in solution was studied in 24 adults (mean weight of 70 kg). The trial was randomized using a triple cross-over design. A burning sensation was reported in 60%, 12% and 0% of subjects up to 15 min after administration of diazepam 35 mg, diazepam 10 mg and placebo, respectively. Endoscopic assessment 24 h after medication showed mechanical irritation in three subjects and local irritation probably caused by diazepam, the vehicle, or both, in four. No correlation was found between subjective complaints and objective findings. Control endoscopy 7 days after medication revealed no pathology. It is suggested that a rectal solution of diazepam in doses up to 0.5 mg kg-1 is a safe form of medication in respect of irritation of the rectal mucosa.

Administration, Rectal↗
PubMedDate not supplied

The effect of treatment on eye-head coordination in Parkinson's disease.

Eye-head movements to target steps of amplitude 3.75 degrees to 30 degrees were analyzed in 9 untreated patients with idiopathic Parkinson's disease. Testing was performed before and after the introduction of a dopamimetic drug (L-dopa or bromocriptine) and compared with 9 normal controls. The patients showed a significantly greater scatter of mean head latencies prior to treatment, although their mean latencies were not significantly prolonged. When compared to controls, the patients' head movements were of reduced peak velocity and gain. Treatment resulted in an improvement of gain but not velocity. Analysis of the frequency of gaze types showed no significant effect of treatment.

Aged↗