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Biomedical subjects

G Clausen

Publications and source records attributed to G Clausen.

At least 19 recordsLinked to original sources
PubMed2006

[Patient satisfaction and geriatric care - an empirical study].

Patients' satisfaction has become a central concept in quality assurance. Despite progress in research in this area is still a lack of data for geriatric patients. Referring to the consumer model, satisfaction can be described as a difference between expectations and assessed performance. The aim of this study is to analyze satisfaction among geriatric patients in an in-patient setting. A personal interview was performed 1-2 days before discharge. Patients suffering for dementia or with problems to communicate were excluded. 124 of 268 geriatric patients who were discharged in 2003 were included (inclusion rate 46.3%). 119 were willing to participate (response rate 96.0%). Respondents were between 61 and 96 years old, 39% were male and 42% had serious functional limitations at time of admission. Multiple linear regression analysis revealed three significant predictors of a combined index of satisfaction and expectations: a) quality of hotel services; b) experience of neglect; c) provision of medical information and skills. In summary, standardized personal questionnaires can provide valid and reliable data of geriatric patients. Satisfaction of elderly patients is negatively affected by neglect and positively influenced by provision of medical information and a good hotel services.

Aged↗
PubMed2006

Initial studies of oxidation processes on filter surfaces and their impact on perceived air quality.

Used filters can be a strong sensory pollutant source. Oxidation processes, especially those initiated by ozone, may contribute to the pollutants emitted from such filters. In the present study, ozone was added to the airstream passing through used ventilation filters. Two flow rates were examined. While the upstream ozone concentration was approximately 75 ppb, the concentrations downstream of the filter were initially 35-50% lower. However, within an hour downstream concentrations were only 5-10% lower than those upstream. These filter samples were then placed for 48 h in nitrogen, ambient air containing less than 5 ppb ozone, or ambient air at an elevated temperature. This resulted in partial regeneration of the ozone removal capability of the filter. In analogous experiments, lower ozone removal occurred when the filter samples were first ventilated for 24 h with ozone-free air before making the measurements. Samples from a new filter removed <10% of the ozone in the airstream, and removal remained relatively constant over time. In companion studies, human subjects assessed the air passing through various used filter samples. In the initial evaluation each of the four filter samples, taken from the same filter and ventilated for 24 h, were assessed to be equivalent. The next evaluation was immediately after the samples had been kept for 24 h in either nitrogen, air, air at an elevated temperature or ozone. The nitrogen-treated filter was assessed to be best, while the ozone-treated filter was assessed to be the worst. The final evaluation occurred after ambient air had passed through the 'treated' filters for 2 h. All such ventilated filters were assessed to be more acceptable than immediately after the 24-h treatments; the ozonized and air-treated filters were the most polluting of the four. Practical Implications The present paper supports previous findings that loaded ventilation filters can be significant sources of sensory pollution. Replacing a loaded filter with a new filter temporarily removes this source of pollution. However, the present study does not provide an answer to how frequently changes are needed under different conditions. The results indicate that in cases of intermittent operation of ventilation systems, the airflow through the polluted filters should be restarted in sufficient time prior to occupancy to purge odorous pollutants that have accumulated on the filter surface. Removal of ozone upstream of the particle filters may further improve perceived air quality in the space downstream of the filter bank. Future efforts related to the development and application of low-polluting filtration systems are warranted.

Air Pollutants↗
PubMed2004

[Effectiveness and efficiency of stationary geriatric treatment of old and very old patients].

In this study we compared characteristics and treatment results in patients of 60 to 79 (group I, n = 682) and of 80 to 100 years of age (group II, n = 593) treated in a geriatric hospital. Neurologic diseases (mainly stroke) predominated in group I (38%), and patients with fractures in group II (53%). Diabetes mellitus and hyperlipidemia were less frequent in patients of group II, but overt cardial insufficiency was more frequent than in group I. While the effectiveness of geriatric treatment was identical in both groups, the efficiency-defined as progress per day-was in some parts slightly higher in group II. There are three independent variables strongly related to the decision of transfer into a nursing home: 1) Barthel Index on discharge; 2) Household-Size (living alone/living not allone); 3) Age.

Accidental Falls↗
PubMed2004

Impact of indoor air temperature and humidity in an office on perceived air quality, SBS symptoms and performance.

UNLABELLED: Perceived air quality (PAQ), sick building syndrome (SBS) symptoms and performance of office work were studied in a real office space at three levels of air temperature and humidity and two levels of ventilation rate (20 degrees C/40%, 23 degrees C/50%, 26 degrees C/60% RH at 10 l s(-1) p(-1) outside air, and 20 degrees C/40% RH at 3.5 l s(-1) p(-1) outside air). Thirty female subjects participated in the experiment. They were exposed to each environmental condition for 280 min. Thermal comfort was maintained at different thermal environments by self-adjustment of clothing. The subjects performed simulated office work throughout each exposure and repeatedly marked a set of visual-analog scales to indicate their perception of environmental conditions and of the intensity of SBS symptoms at the time. The study confirmed the previously observed impact of temperature and humidity on perceived air quality and the linear correlation between acceptability and enthalpy. The impact on perceived air quality of decreasing the ventilation rate from 10 to 3.5 l s(-1) per person could be counteracted by a decrement of temperature and humidity from 23 degrees C/50% RH to 20 degrees C/40% RH. Performance of office work was not significantly affected by indoor air temperature and humidity. However, several SBS symptoms were alleviated when the subjects worked at low levels of air temperature and humidity, which implies that a longer term exposure to low indoor air temperature and humidity might help to improve the performance of office work. PRACTICAL IMPLICATIONS: The findings of this study indicate the importance of indoor air temperature and humidity on perceived air quality and SBS symptoms. In practice, the required ventilation rate for comfort and health should no longer be independent of indoor air temperature and humidity.

Adult↗
PubMed2004

Ventilation filters and indoor air quality: a review of research from the International Centre for Indoor Environment and Energy.

UNLABELLED: The presence of a used filter in a ventilation system can have an adverse impact on perceived air quality, SBS symptoms, and performance of office work. The present paper reviews the studies leading to this conclusion and discusses recent work that has been performed in a search for the mechanisms involved. One promising hypothesis involves chemical reactions on the surface of the collected particles in the formation of noxious compounds. Finally, a discussion on engineering solutions is presented. PRACTICAL IMPLICATIONS: Loaded particle filters provide a significant source of air pollution. To counteract this, filters should be changed frequently or an alternative method of removing particles from the air should be applied.

Air Pollution, Indoor↗
PubMed2000

[Asthma caused by methylene-diphenyl-diisocyanate cast in a nurse].

A case of a 35 year-old female nurse without atopic disposition is presented. For one year (1990-1991), she worked in an emergency room, applying synthetic casts containing MDI 0-3 times daily. She developed rhinitis, itchy eyes and nightly wheezing, during employment in the emergency room, with subsequent serious asthma attacks in 1992 and 1996. Just before the last attack, the patient's husband had used insulation foam containing MDI. A specific bronchial provocation test was performed with MDI-based synthetic cast material. The patient developed an asthma attack after seven hours, with a 48% drop in FEV1, suggesting that MDI is the causative agent.

Adult↗
PubMed2000

The effects of outdoor air supply rate in an office on perceived air quality, sick building syndrome (SBS) symptoms and productivity.

Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in a normally furnished office space (108 m3) ventilated with an outdoor airflow of 3, 10 or 30 L/s per person, corresponding to an air change rate of 0.6, 2 or 6 h-1. The temperature of 22 degrees C, the relative humidity of 40% and all other environmental parameters remained unchanged. Five groups of six female subjects were each exposed to the three ventilation rates, one group and one ventilation rate at a time. Each exposure lasted 4.6 h and took place in the afternoon. Subjects were unaware of the intervention and remained thermally neutral by adjusting their clothing. They assessed perceived air quality and SBS symptoms at intervals, and performed simulated normal office work. Increasing ventilation decreased the percentage of subjects dissatisfied with the air quality (P < 0.002) and the intensity of odour (P < 0.02), and increased the perceived freshness of air (P < 0.05). It also decreased the sensation of dryness of mouth and throat (P < 0.0006), eased difficulty in thinking clearly (P < 0.001) and made subjects feel generally better (P < 0.0001). The performance of four simulated office tasks improved monotonically with increasing ventilation rates, and the effect reached formal significance in the case of text-typing (P < 0.03). For each two-fold increase in ventilation rate, performance improved on average by 1.7%. This study shows the benefits for health, comfort and productivity of ventilation at rates well above the minimum levels prescribed in existing standards and guidelines. It confirms the results of a previous study in the same office when the indoor air quality was improved by decreasing the pollution load while the ventilation remained unchanged.

Adolescent↗
PubMed1999

Perceived air quality, sick building syndrome (SBS) symptoms and productivity in an office with two different pollution loads.

Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P = 0.04) and significantly lower levels of reported effort (p = 0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P = 0.003), typing 6.5% less text than when the pollution source was absent from the office Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.

Adult↗
PubMed1999

Impact of temperature and humidity on chemical and sensory emissions from building materials.

The chemical and sensory emissions from five building materials (carpet, polyvinyl chloride (PVC) flooring, sealant, floor varnish and wall paint) were tested under different combinations of temperature and relative humidity in the ranges 18-28 degrees C and 30-70% relative humidity (RH). The experiment was performed in a climate chamber where a specially designed test system was built to study emissions from the five materials. The test system could provide different temperatures and humidities of air around the materials, while the air, after being polluted by the emissions from the materials, could be reconditioned to 23 degrees C and 50% RH for sensory assessments. The experiment was designed to separate the direct impact of temperature and humidity on perception from the impact on sensory emission. The study found little influence of temperature on the emissions from the five materials whether expressed in chemical or sensory terms. The effect of humidity was found to be significant only for the waterborne materials--floor varnish and wall paint. Compared with the direct impact of temperature and humidity on the perception of air quality, the impact of temperature and humidity on sensory emissions from the building materials has a secondary influence on perceived air quality.

Adult↗
PubMed1998

[How does subjective well-being of elderly patients during inpatient geriatric rehabilitation change?].

During rehabilitation of patients suffering from a recent hip fracture, we evaluated the development of several aspects of their subjective well-being (n = 87, age: 70 to 94)). In most cases, a deterioration of subjective well-being due to the consequences of the hip fracture could be prevented; the well-being improved in most cases. When discharged, the subjective well-being of our patients was comparable to the well-being of similar-aged people living at home.

Activities of Daily Living↗
PubMed1994

Glomerular filtration and tubular absorption of the basic polypeptide aprotinin.

The basic polypeptide aprotinin (Ap), mol. wt 6500, pI 10.5, is filtered in the glomeruli, virtually completely taken up by the proximal tubular cells and retained there for many hours. This process was studied in rats by determining the renal plasma clearance (CAp) as the amount of [125I]Ap accumulated in the kidney plus that excreted in the urine per unit of time divided by the integrated plasma concentration. In periods lasting 4-20 min after i.v. bolus injection or infusion to constant plasma concentration, CAp was 65% of glomerular filtration rate (GFR) estimated as kidney plus urinary clearance of [51Cr]EDTA (Ccr-EDTA). Less than 0.8% of the filtered Ap appeared in the urine. CAp varied inversely with plasma protein concentration in mg ml-1: CAp/Ccr-EDTA = 0.98-0.0058 x Ppr, corresponding to a glomerular Gibbs-Donnan distribution for a net molecular charge of +6, in agreement with the amino acid composition of Ap. CAp (kidney + urinary) was not altered by inhibiting tubular uptake of [125I]Ap by maleate or by exceeding the uptake capacity with large doses of unlabelled Ap. Neutralized Ap (malonylated) did not accumulate in the kidney, but showed a urinary clearance indistinguishable from that of [51Cr]EDTA. Both CAp and Ccr-EDTA were reduced to 0.04 ml min-1 when glomerular filtration pressure was lowered by ureteral stasis and increased Ppr (80-90 mg ml-1). These findings indicate: (1) no steric or charge restriction to filtration of Ap in the glomerular membrane, (2) the Gibbs-Donnan equilibrium should be considered when estimating glomerular sieving of charged polypeptides in intact animals (3) charge dependent tubular uptake, (4) little or no transtubular transport of intact Ap, (5) no appreciable tubular uptake of Ap from the peritubular side and (6) local renal accumulation of Ap in a period of up to 20 min may be used to estimate local glomerular filtration and/or local proximal tubular reabsorption rates. Model analysis based on the appearance of 125I in plasma, the time course of renal Ap content, and literature data on subcellular Ap distribution are consistent with two populations of endosomes, transporting Ap at widely different rates from the proximal tubular brush border to the lysosomes where breakdown occurs at a high rate.

Absorption↗
PubMed1992

Myogenic vasoconstriction in the rat kidney elicited by reducing perirenal pressure.

Autoregulation of renal blood flow is generally believed to result from tubuloglomerular feedback and/or a vascular myogenic mechanism, but there is no consensus on the relative importance of these mechanisms. We designed an experiment in which tubuloglomerular feedback would tend to oppose a myogenic response: the denervated kidney in situ was enclosed in an airtight chamber and exposed to a 35 mmHg subatmospheric pressure for 1 to 10 minutes. Renal blood flow recorded by an electromagnetic flowmeter fell by 33% in the course of a few seconds. Renal venous concentration of inulin showed no consistent change, indicating similar reduction in glomerular filtration rate. Since urine flow also fell, it is likely that the tubular flow rate was reduced. The kidney volume expanded by 10-20%, and subcapsular interstitial fluid pressure was reduced from 6.8 to -8.6 mmHg. Arterial pressure remained unchanged, while renal venous pressure inside the chamber fell from 9.4 to 5.8 mmHg. Normalization of perirenal pressure gave rapid normalization of all parameters. Elevation of ureteral pressure attenuated or even prevented the renal blood flow reduction. Renal decapsulation or sympathetic blockade by phentolamine, or infusion of furosemide or 0.9% NaCl to inactivate tubuloglomerular feedback, did not prevent the renal blood flow reduction. We interpret the results to indicate that myogenic vasoconstriction greatly overpowered TGF and even surpassed the constriction predicted by a mathematical model based on maintenance of the preglomerular wall tension as estimated from transmural pressure.

Animals↗
PubMed1986

The double-priming paradigm: a tool for analyzing the functional significance of endogenous event-related brain potentials.

A new paradigm to study the functional significance of 'P300' is presented. Its advantages are: The precise definition and manipulation of cognitive operations which are triggered by the very same events as used for ERP extraction; and a systematic control over the probability of events known to affect endogenous event-related potential components (probabilities of single events, event categories, and event sequences). By employing the paradigm in two experiments with visual stimuli, three subcomponents of 'P300' were identified: P3a; P3b; and positive Slow Wave (pSW). Experimental manipulations revealed that P3b is related to the information processing resources required to alter a perceptual set and pSW to the resources required when abstract information permanently stored in memory must be retrieved. The data further revealed that the same-different disparity in response latency for matching letters has at least two ERP correlates: A difference in P3b latency; and a difference in the amplitude of a negative recess between P3a and P3b.

Adult↗
PubMed1986

Relative flow of blood cells, platelets, and microspheres in outer and inner renal cortex.

Blood platelets (Pl) may attain a relatively high marginal concentration in arterioles, perhaps also in arteries. Along a renal interlobular artery, blood passes several successive arterioles, each arteriole receiving a small flow fraction from a narrow zone adjacent to the artery wall. Thus, in theory, the Pl concentration should cumulatively decrease as the blood approaches the outer cortex, contrary to the concentration of red and white blood cells (RBC and WBC). This was tested by assessing the concentrations of these blood elements, and for comparison, the concentrations of 0.3-, 1.8- and 3.5-micron microspheres (MS), in serial blood samples from veins separately draining the outer and inner cortex in cat kidney. The outer-to-inner cortical concentration ratio was 1.28 for WBC, 1.04 for RBC, and 0.75 for Pl, confirming the working hypothesis. The RBC demargination corresponded to that of MS smaller than 1.8 micron, the demargination of WBC to that of MS larger than 3.5 micron. In contrast to Pl the even smaller 0.3-micron MS were not marginated. Thus, the margination of platelets may not be due merely to their small size.

Animals↗
PubMed1984

Tumor uptake of vincristine during close arterial vs systemic constant-rate infusion: experiments on sarcoma transplants in the rat kidney.

The uptake of vincristine (VCR) by normal tissues and by sarcomas transplanted to both kidneys in rats was studied at 10 min after constant rate infusion of 1 mg/kg body wt into one renal artery for 3, 10 and 30 min. Since the selectively infused kidney extracted only 2.5% of the total dose at the first renal passage, the present model provides a direct comparison between systemic and selective i.a. infusion of VCR in each animal. Tumor VCR uptake was 2.8 times higher and the corresponding blood VCR concentration time product about 4 times higher on the selectively infused side than on the contralateral side. Reduction of renal blood flow by clamping the selectively infused renal artery raised the local VCR blood concentration by another 10 times during 10 min infusion and further doubled the tumor uptake of VCR. Thus a 5-6 times higher VCR concentration in the tumor was achieved as compared to that obtainable by systemic administration of the same total dose. The results are compatible with a saturable mechanism of VCR uptake by renal tissue and tumors.

Animals↗