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Biomedical subjects

C Jensen

Publications and source records attributed to C Jensen.

159 records · Page 9Linked to original sources
PubMedDate not supplied

Oxygen consumption and acid-base balance during shallow hypothermia in the pigeon.

In pigeons, during shallow nocturnal hypothermia induced by food deprivation, body temperature falls to values between 35 degrees C and 38 degrees C. Body temperature, oxygen consumption, and arterial blood pH and PCO2 were recorded during the entrance into such nocturnal hypothermic periods. In vivo pH was kept constant, while in vivo PCO2 increased slightly during hypothermia. This caused the temperature-corrected value of pH (pH*, measured at 40 degrees C) to fall by -0.014 units/degrees C, and the total CO2-content to rise by 3.2 mM, an increase of 16%. These changes in the acid-base balance represent, in effect, a respiratory acidosis that closely parallels the normal buffer line for pigeons. Q10 values, relating oxygen uptake to body temperature, were higher than 4.0 at the very beginning of the entrance into hypothermia, indicating that the metabolic rate was actively inhibited. However, the present results do not indicate any relationship between the acidosis and the inhibition of the metabolic rate.

Acid-Base Equilibrium↗
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Thoracic outlet syndrome: provocative examination maneuvers in a typical population.

Provocative examination maneuvers were assessed in 200 upper extremities of 100 volunteers to determine the prevalence of positive responses in the typical population. The Adson, costoclavicular, and hyperabduction maneuvers were assessed for vascular and neurologic responses. Fifteen (7.5%) extremities had a Tinel's sign. The vascular response was present in 27 (13.5%) extremities for the Adson maneuver, 94 (47%) extremities for the costoclavicular maneuver, and 114 (57%) extremities for the hyperabduction maneuver. The neurologic response was present in 4 (2%) extremities for the Adson maneuver, 20 (10%) extremities for the costoclavicular maneuver, and 33 (16.5%) extremities for the hyperabduction maneuver. The vascular response is more common than the neurologic response in the typical population.

Adult↗
PubMedDate not supplied

Cannibalism and coprophagy are modes of transmission of Blastocrithidia triatomae (Trypanosomatidae) between triatomines.

Transovarial transmission was not detectable among Blastocrithidia triatomae-infected Triatoma infestans. Rather, B. triatomae was transmitted directly between triatomines by cannibalism and coprophagy. Cannibalism conditions that excluded coprophagy always resulted in an infection of Dipetalogaster maxima. The efficiency of transmission was not influenced by the blood source--mice or chickens--fed to the infected donor bugs although chicken blood lyses the epimastigotes of the stomach population. Triatoma infestans was infected by coprophagy only if fed, not if unfed. Blastocrithidia triatomae in dry feces was taken up only if the feces were redissolved in fresh feces. Infections also appeared in groups of bugs fed on chickens previously used for feeding infected bugs.

Animals↗
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Intrathecal release of nitric oxide and its relation to final brain damage in patients with stroke.

The potential role of inflammatory mechanisms in the pathophysiology of ischemic brain damage has intensely been discussed. We have recently demonstrated that stroke patients display an intrathecal production of proinflammatory cytokines early after onset of symptoms. IL-1beta, one of these cytokines, stimulates the production of nitric oxide (NO), a potent inflammatory mediator. The aim of the present study was to investigate the intrathecal levels of nitrate, one of the main metabolites of NO in acute stroke and to relate its levels to brain damage. Stroke patients were prospectively studied with clinical evaluation, radiological assessment and analysis of intrathecal levels of nitrate by gas chromatography/mass spectrometry. In addition, simultaneous analyses of cytokines and of soluble Fas/APO-1 and bcl-2, two proteins regulating apoptosis, were performed. The intrathecal levels of nitrate were not significantly different in stroke patients compared to controls throughout the observation period. However, the intrathecal levels of nitrate increased significantly 3 months after stroke onset compared with the first 3 days. Interestingly, the levels of nitrate measured at stroke onset were negatively correlated to the final size of infarct volume (r = -0.69, p < 0.05) measured by MRI. In addition, patients with large infarcts displayed significantly (p = 0.008) lower levels of nitrate in cerebrospinal fluid compared to patients with small infarcts during the first 3 days after stroke onset. In contrast, the intrathecal levels of nitrate were significantly positively correlated (r = 0.79, p < 0. 001) to the neurological deficit and negatively correlated (r = -0. 76, p < 0.05) to bcl-2, a protein downregulating neuronal apoptosis, in the late stage of the stroke. Early NO production is associated with a smaller infarct volume, suggesting a protective effect, whereas late NO production is associated with severer neurological deficits, suggesting a neurotoxic effect. Treatment trials pertaining to modulate NO production in stroke should take into consideration the dual effect of NO on ischemic brain damage.

Adult↗
PubMedDate not supplied

Phase response curve for the ultradian rhythm of the lateral leaflets of Desmodium gyrans using DC current pulses.

In the present study the leaf movement rhythm was perturbed by the application of DC current pulses (15 microA, 10 seconds, voltage applied: 10 V) to the upper part of the pulvinus, passing through the pulvinus and its stalk. The pulses were applied at four different positions of the leaflets: when the leaves were at the lowermost position, when moving up, at the uppermost position and when moving down. The pre-perturbed and the post-perturbed rhythms were compared. We found that the rhythms were shifted in phase and the phase shifts observed at the four different positions of the leaflets were significantly different in magnitude as well as direction. Furthermore, we could also observe phase advances, which is in contrast to an earlier finding. A phase response curve (PRC) was constructed to illustrate the sensitivity of the oscillating leaflet system to DC pulses. Substantial delays of about 50 s (as compared to the period of about 200 s) were obtained when pulses were administered at the lowermost position and when leaflet were moving upwards, while advances or no phase shifts were recorded in the uppermost position and when leaflet were moving down respectively.

Activity Cycles↗
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Treatment of acute maxillary sinusitis. IV. Ampicillin, cephradine and erythromycinestolate with and without irrigation.

Six groups, each containing 50 patients with acute maxillary sinusitis, were treated with ampicillin plus nasal decongestant, ampicillin plus irrigation, cephradine plus nasal decongestant, cephradine plus irrigation, erythromycinestolate plus nasal decongestant, erythromycinestolate plus irrigation. The diagnosis was radiologically established and the healing likewise radiologically assessed on the fifth, tenth and fifteenth day. Treatment was given for 10 days. All groups demonstrated a similar radiological healing except cephradine plus nasal decongestant which was inferior to the others. Contrarily, side effects were least frequent in the cephradine groups and most frequent in patients cured with ampicillin. The difficulty in choosing the best treatment is discussed in relation to such factors as therapeutic results, side effects, long-term consequences of antibiotic treatment, establishment of any bacterial etiology and penetration characteristics of antibiotics into the diseased sinus.

Acute Disease↗
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Treatment of acute maxillary sinusitis. V. Amoxicillin azidocillin, phenylpropanolamine and pivampicillin.

One hundred and seventy-five patients with clinical symptoms of acute maxillary sinusitis, the diagnosis confirmed radiologically by mucous membrane thickening and secretion, were consecutively allocated to four different treatment groups: amoxicillin, azidocillin, phenylpropanolamine, and pivampicillin. The cure course was followed up radiologically on days 5, 10, and 15. The outcome of treatment was somewhat more beneficial after 5 days for amoxicillin and after 10 days for azidocillin, but slightly less beneficial with phenylpropanolamine after 10 and 15 days. The numbers of side effects were similar for the different treatment groups. The four treatment modes in question are compared with 19 others previously used in a large material consisting of more than 1000 patients with acute maxillary sinusitis.

Amoxicillin↗
PubMedDate not supplied

Radiography and ultrasonography in paranasal sinusitis.

In order to analyze whether ultrasonography with a reasonable degree of confidence can replace radiography in the diagnosis of sinusitis, 138 patients with clinical signs of sinusitis were examined with both methods. It was found that maxillary sinus fluid was recognized ultrasonographically with a confidence that increased with the amount of fluid, judged from radiographic examinations. In a sub-group of 45 cases, fluid confirmed by maxillary sinus puncture was detected by ultrasonography in 35/45 sinuses (78%) and by radiology in 38/45 sinuses (84%). In patients with radiographically normal maxillary sinuses, the correlation to ultrasound was good. However, mucosal swelling and polyps or cysts observed at radiography were poorly demonstrated by ultrasonography. In addition, the ultrasound method was not reliable for frontal sinus diagnosis. It was concluded that ultrasonography can be recommended in maxillary sinusitis for follow-up of treatment and as a screening method before sinus radiography.

Adult↗
PubMedDate not supplied

Quantification of muscular activity in the shoulder region during monotonous repetitive work.

The purpose of this preliminary study was to evaluate the degree of myoelectric activity (EMG) in the shoulder muscles during repetitive monotonous work cycles in order to assess the load on the shoulder muscles. The tasks were video recorded and the movements performed were analyzed with a direct computer-based observational method (OS-WALD). The amplitude distribution probability function (ADPF) of the surface EMG from the deltoideus lateralis and trapezius pars descendens muscles was analyzed in 6 persons working on assembly lines. For each subject, "on-site" EMG and video recordings were performed over 10-minute periods at four different workstations on the same day. Force/EMG amplitude calibration curves had been previously calculated for the same subjects using a strain-gauge dynamometer. The results obtained during the working periods were the following: the mean static contraction level, as defined by Jonsson (13), was 1.3% MVC in the trapezius muscle and 0.5% MVC in the deltoid muscle; the medium contraction level was 5.2% MVC in the trapezius and 1.7% MVC in the deltoid; the peak contraction level was 17% MVC in the trapezius and 6.2% MVC in the deltoid. When compared to previously suggested upper limits of ADPF levels, all the contraction levels monitored were below the recommended limits. The assessment of musculoskeletal load in the shoulder region via EMG and video recordings led us to conclude that the work cycles examined were characterized by low-repetitive monotonous work and were well organized in order to avoid the occurrence of musculoskeletal injuries.

Adult↗