Biomedical subjects

L Knudsen

Publications and source records attributed to L Knudsen.

At least 37 records · Page 2Linked to original sources

PubMed1997

Evaluation of bactericidal activity and lag of regrowth (postantibiotic effect) of five antiseptics on nine bacterial pathogens.

Lag of regrowth or postantibiotic effect (PAE) relates to suppression of bacterial regrowth following short exposure to an antimicrobial agent. A delay in regrowth has not yet been studied for antiseptics to any great extent. We therefore examined and compared the lag of regrowth and the bactericidal activity of five antiseptics (chloramine T, chlorhexidine, povidone-iodine, phenoxyethanol and mandelic-lactic acid) against nine bacterial pathogens. Delay in regrowth was determined by application of two concentration-time schedules: a test concentration at the MBC with a contact time of 1 h or using fixed suboptimum concentration of each antiseptic for 2 min (optimum concentrations sterilized the culture, impeding assessment of regrowth) followed by a neutralization-dilution step and subsequent viable counting to follow bacterial regrowth. Each antiseptic displayed a different spectrum of activity in terms of MIC or MBC, bactericidal effect and lag of regrowth. The delay in regrowth varied from 0 to 5.7 h with only a few discrepancies between the two treatment schedules. Mandelic-lactic acid and chloramine T induced a significantly longer lag as compared with the other agents, whereas phenoxyethanol produced the shortest lag values. No significant correlation between the killing rate and the lag of regrowth could be demonstrated. Information on bactericidal activity, as well as lag of regrowth, could be a useful screening method for the efficacy of antiseptics. Moreover, data on lag of regrowth could contribute to the choice of antiseptic and guide in determining the optimum interval between repeated applications of antiseptics.

Anti-Infective Agents, Local↗

PubMed1996

Monitoring thrombin generation with prothrombin fragment 1.2 assay during cardiopulmonary bypass surgery.

UNLABELLED: Despite high plasma levels of heparin during cardiopulmonary bypass surgery, activation of the coagulation system has been reported. We hypothesize that the coagulation system activity most appropriately could be assessed by molecular markers of thrombin generation. The aim of the present study was to describe the changes in thrombin generation during CPB, using prothrombin fragment F1 + 2 (F1.2) as an indicator and evaluate different blood sampling regimens for interpretation of the F1.2 measurements. Twenty patients, operated under extracorporeal circulation with coronary artery bypass grafting (CABG), comprised the study material. The heparin levels were maintained above 2.5 IU/ml throughout the bypass procedure and the functional AT-III level was kept above 0.5 U/ml. Despite of this anticipated inactivation of the coagulation system, the concentrations of F1.2 and FpA increased throughout CPB, particularly after release of the aortic crossclamp. F1.2 and FpA correlated significantly (R = 0.69). No statistically significant correlation was found between F1.2 formation rate and age, bodyweight, baseline ACT, ACT after 200 IU heparin/kg, average heparin concentration during CPB or average AT-III level during CPB. CONCLUSIONS: Thrombin formation seems to be a continuous process during CPB despite adequate heparinization. The pattern of thrombin generation can be assessed most appropriately in terms of F1.2 generation rate. Extraordinary high levels of F1.2 were seen after release of the aortic crossclamp, indicating that the periods before and after aortic crossclamping should be evaluated separately.

Adult↗

PubMed1996

A study of cognitive functions in young Parkinsonian patients.

The purpose of the study was to evaluate the neuropsychological performance of younger Parkinson's disease (PD) patients compared to healthy controls. A group of young optimally treated PD patients younger than 56 years was pair-matched with a group of healthy controls for age, social class and the two WAIS subtests "vocabulary" and "similarities". As a group, the PD patients were satisfactory in verbal logical intelligence, but evaluation of neuropsychological tests showed difficulties in short memory span, constructional function and logical visual sequential cognition. Young PD patients have some cognitive impairment for which they are able to compensate for a time because of preserved intelligence. More attention should be paid to possible problems in their jobs and social life.

Adult↗

PubMed1996

Five to 10 years follow-up after total parathyroidectomy and autotransplantation of parathyroid tissue: evaluation of parathyroid function by use of ischaemic blockade manoeuvre.

The aim of the present study was to assess the long-term function of autotransplanted parathyroid tissue in patients with chronic renal disease. We examined the medical records of a consecutive series of 21 patients with chronic renal failure, who had undergone total parathyroidectomy with autotransplantation. During the time of follow-up, on average 79 months, one patient developed graft-dependent recurrent hyperparathyroidism and one patient suffered from persistent hypoparathyroidism. Nine of the patients were available for a clinical study. In these patients we measured the plasma concentration of intact PTH in blood from the arm contralateral to the graft-bearing arm at rest and during a short-lasting ischaemic blockade of the graft site from the circulating blood. At rest all nine patients had parathyroid hormone (PTH) values within the normal range. The ischaemic blockade produced a marked reduction in the plasma concentration of intact PTH in eight of the patients indicating well functioning autografts. Prior to the examination the patient with recurrent hyperparathyroidism had undergone resection of the autograft. In this patient, ischaemia of the former graft site did not cause any change in the concentration of PTH indicating normally functioning residual parathyroid tissue in the neck. Thus, the ischaemic blockade manoeuvre seems suitable for the assessment of autografted parathyroid tissue. Our results indicate that total parathyroidectomy with autotransplantation provides a rational alternative to the surgical treatment of secondary hyperparathyroidism.

Adult↗

PubMed1996

Regional differences exist in elastic wall properties in the ureter.

According to classical mechanical theory, the passive elastic properties of a distensible tube are important for the resistance to flow. The aim was to study luminal dimensions under pressure loading and the tension-strain distribution of the ureter in anaesthetized pigs by means of impedance planimetry. Stepwise inflation of an intraluminal balloon in which the cross-sectional area (CSA) and pressure were measured provided the distension stimulus in the ureteropelvine junction, in the midureter and in the intramural part of the ureter at the ureterovesical junction. The circumferential tension-strain distributions were computed from steady state values of these measurements. The CSA always reached equilibrium within the two-minute distension period. The steady state pressure-CSA curves were nonlinear and differed between the three measuring points (p < 0.001). The most pronounced difference was found between the ureteropelvine junction and the two other measuring points. At the lowest applied pressure of 1 kPa the steady state CSA was 15.4 +/- 1.1, 16.6 +/- 1.1, and 19.9 +/- 19.9 mm2 in the intramural part, middle part and ureteropelvine junction, respectively. At the maximum pressure the figures were 41.9 +/- 2.9, 47.0 +/- 2.7, and 73.1 +/- 8.2 mm2 for the three locations, respectively. The circumferential tension-strain distributions were nonlinear with an exponential-like behaviour. The tension-strain curve obtained from the ureteropelvine junction was translated to the right compared to the curves obtained from the two other measuring points (p < 0.05) indicating that the ureteropelvine junction was more compliant than the two other locations.

Analysis of Variance↗

PubMed1995

[Psychosocial aspects of disseminated sclerosis].

Using multiple sclerosis as a model, it is demonstrated how a chronic neurological disorder has psychosocial consequences during the period between onset and diagnosis, at the time of diagnosis, and in the post-diagnostic period. The impact of the disorder on self-esteem, civil status, habitation, economy, social and leisure activities and need for help is described. It is concluded that it will increasingly be expected that the physician has knowledge of these relations.

Denmark↗

PubMed1995

Acute and chronic pain syndromes in multiple sclerosis. A 5-year follow-up study.

Forty-nine (22 males, 27 females) patients with definite multiple sclerosis were examined twice with 5 years interval regarding acute (less than 1 month duration) and chronic (more than 1 month duration) pain syndromes. From the first to the second examination a significant increase was found in the number of acute and chronic pain syndromes, including tension and pain in the extremities, spasms, low back pain, Lhermitte's sign and neuralgia. The increase included both men and women. The increase was especially found in patients with deterioration of disability.

Acute Disease↗

PubMed1995

The use of non-medical/alternative treatment in multiple sclerosis. A 5 year follow-up study.

Forty-nine patients (22 males, 27 females) were examined and interviewed with 5 years interval in order to determine the extent of the use of non-medical (alternative) treatment and whether the use influenced the natural course of multiple sclerosis (MS). Using clinical course, Kurtzke Disability Status scale, bladder and bowel function, neuropsychological tests, psychological tests, divorce and self-assessment score as parameters, it was found that non-medical treatment did not alter the course of MS. To confirm this result a clinical trial in a controlled design is needed. The use of non-medical treatment declined over the 5 years from 55% to 27%. The use of non-medical treatment could be interpreted as an indicator of psycho-social difficulties in MS patients.

Adult↗

PubMed1994

[Midazolam and lorazepam as premedication. A randomized double-blind study].

Oral administration of midazolam and lorazepam as premedication was compared in a double-blind randomized clinical trial. Eighty patients scheduled for minor gynaecological surgery in general anaesthesia and 80 patients scheduled for hip arthroplasty in spinal anaesthesia were included. Assessments were: 1. patients subjective evaluation of the premedication, 2. sedation scale, 3. recovery of cognitive function assessed by Simple Paper-and-Pencil test and Postbox test, 4. amnesic effects. In the general anaesthesia group midazolam caused less postoperative sedation, less postoperative amnesia and cognitive function returned more rapidly. In the spinal anaesthesia group cognitive function returned more rapidly after midazolam. Midazolam should be preferred for premedication if rapid recovery is desired.

Administration, Oral↗

PubMed1994

Cancer risk in humans predicted by increased levels of chromosomal aberrations in lymphocytes: Nordic study group on the health risk of chromosome damage.

Cytogenetic assays in peripheral blood lymphocytes (PBL) have been used extensively to survey the exposure of humans to genotoxic agents. The conceptual basis for this has been the hypothesis that the extent of genetic damage in PBL reflects critical events for carcinogenic processes in target tissues. Until now, no follow-up studies have been performed to assess the predictive value of these methods for subsequent cancer risk. In an ongoing Nordic cohort study of cancer incidence, 3182 subjects were examined between 1970 and 1988 for chromosomal aberrations (CA), sister chromatid exchange or micronuclei in PBL. In order to standardize for the interlaboratory variation, the results were trichotomized for each laboratory into three strata: low (1-33 percentile), medium (34-66 percentile), or high (67-100 percentile). In this second follow-up, a total of 85 cancers were diagnosed during the observation period (1970-1991). There was no significant trend in the standardized incidence ratio with the frequencies of sister chromatid exchange or micronuclei, but the data for these parameters are still too limited to allow firm conclusions. There was a statistically significant linear trend (P = 0.0009) in CA strata with regard to subsequent cancer risk. The point estimates of the standardized incidence ratio in the three CA strata were 0.9, 0.7, and 2.1, respectively. Thus, an increased level of chromosome breakage appears to be a relevant biomarker of future cancer risk.

Adult↗

PubMed1994

[Data and quality assurance tools from a new cardiac center in Denmark].

Open heart surgery was established at Aalborg Hospital in 1992. In the time period March to December 1992 cardiac anaesthesia was administered in 98 operations utilizing extracorporeal circulation and cardiopulmonary bypass. Mortality in coronary artery surgery was 1.6%. All patients were prospectively registered using a new dataform allowing registration of 228 patients related variables concerning preoperative status, course of anaesthesia and perfusion, surgery and postoperative intensive care. Quality assurance in cardiac surgery requires risk factor analysis, and registration of numerous data is a necessary tool. The software for our database system has been developed and programmed using the database programme dBASE IV from the Ashton/Tate Corporation.

Adult↗

PubMed1994

Elastic wall properties and collagen content in the ureter: an experimental study in pigs.

We used an impedance planimetric method to look at elastic wall properties of ureter in ten anaesthetized pigs. A balloon was stepwise inflated and deflated in the ureteropelvine junction, in the mid-ureter, and in the intramural part of the ureter at the ureterovesical junction with pressures up to 70 cmH2O, while the pressure and balloon cross-sectional area (Bcsa) were measured simultaneously. The elastic wall parameters were calculated from these measurements. At sacrifice, tissue samples were collected for analysis of collagen content of the ureteral wall. A non-linear clockwise relation (hysteresis loops) between Bcsa and balloon pressure was demonstrated. At maximal inflation of the balloon, the Bcsa, wall tension, and compliance were 35.28 +/- 3.52, 38.44 +/- 3.23, and 61.36 +/- 8.09 mm2, 230.71 +/- 12.82, 242.38 +/- 10.49, and 302.17 +/- 20.03 cmH2O x m, and 0.167 +/- 0.047, 0.124 +/- 0.002, and 0.182 +/- 0.040 mm2 x cmH2O-1 in the intramural part of the ureter, middle part, and ureteropelvine junction, respectively. The collagen content was 0.3249 +/- 0.0077, 0.3301 +/- 0.0066, and 0.3457 +/- 0.0060 mg x mg-1 dry defatted weight in the intramural part, in the middle, and in the ureteropelvine junction, respectively. The collagen content of the ureteropelvine junction was significantly higher than that of the middle of ureter (P < 0.02) and than that of the intramural part (P < 0.05). No significant correlations were found between the elastic parameters at maximal inflation of the balloon and the collagen content (P < 0.10). In conclusion the elastic wall properties were significantly different in the three ureteral segments and the collagen content of the ureteropelvine junction differed from that of the two distal locations. However, no relationship between the wall properties and the collagen content was found.

Animals↗

PubMed1994

Multiple sclerosis: correlation of anxiety, physical impairment and cognitive dysfunction.

The aim of the study was to examine the correlation between anxiety and physical impairment and to discover whether anxiety correlated with specific forms of cognitive dysfunction. Ninety-four patients (42 females, 52 males) with definite MS entered the study. Anxiety was measured using the State-Trait Anxiety Inventory, physical impairment by means of the Kurtzke Disability Status scale, and cognitive impairment by using the Trail Making, Symbol Digit Modalities, Auditory Verbal Learning, Story Recall and the Recurring Figures tests. Moderately handicapped patients (DSS 4-5) showed signs of anxiety, and physical impairment correlated with anxiety (p < 0.05; d.f. 1.92). Trail Making also correlated with anxiety (p < 0.01; d.f. 1.86). On the basis of the results of this and previous studies, it is concluded that anxiety can be a sign of cognitive dysfunction, physical impairment or social strain.

Adult↗

PubMed1994

Tomographic cerebral blood flow measurement during carotid surgery.

OBJECTIVES: The aim of the study was to depict regional cerebral blood flow (rCBF) during carotid cross clamping using 99mTechnetium-hexamethylpropylene amine oxime (TcHMPAO). This tracer rapidly passes the blood-brain barrier and is retained for hours in the brain tissue. Injecting TcHMPAO during surgery and performing single photon emission computer tomography (SPECT) scanning shortly after the operation thereby pictures rCBF at the time of injection. DESIGN: Ongoing prospective study. SETTINGS: Departments of Vascular Surgery, Neurology and Anaesthesiology, University Hospital, Rigshospitalet, Copenhagen, Denmark. MATERIAL: 15 patients who during a period of 4 months underwent carotid endarterectomy. CHIEF OUTCOME MEASURES: Prior to surgery rCBF was determined using 133Xe and SPECT. Intraoperatively stump pressure was measured and a bolus of TcHMPAO was injected for later SPECT measurement. MAIN RESULTS: We found a significant correlation between stump pressure and enhancement of side-to-side asymmetry in rCBF due to carotid cross clamping. Pronounced variations were seen in which regions were deprived of perfusion during clamping. CONCLUSION: TcHMPAO allows tomographic assessment of CBF during carotid surgery. This method may serve as a reference tool in future research on intraoperative cerebral haemodynamics.

Aged↗

PubMed1994

Multiple sclerosis: methodological aspects of cognitive testing.

In a cross-sectional study of 94 patients (42 males, 52 females) with definite multiple sclerosis (MS) in the age range 25-55 years, the correlation of neuropsychological tests with the ability to read TV-subtitles and with the use of sedatives is examined. A logistic regression analysis reveals a significant correlation between results of an attention and perceptual motor speed test i.e. Symbol Digit Modalities test and the ability to read TV-subtitles, but no correlation was found with another attention and perceptual motor speed test, or verbal or visual memory. No correlation between the use of sedatives and results on neuropsychological tests was found. Anxiety was not correlated with the ability to read TV-subtitles. It is concluded that visual deficits but not the use of sedatives may be a confounding factor in neuropsychological testing in MS.

Adult↗

PubMed1993

[Educational requirements of younger psychiatrists].

In order to define the requirements junior medical staff in postgraduate psychiatric training would wish to make for future postgraduate training in adult psychiatry, a questionnaire with 66 questions was sent in June 1990 to postgraduate trainees at all departments of child psychiatry and adult psychiatry in the country. Response was anonymous. The article deals with the responses from 264 persons either intending to undergo specialist training in adult psychiatry or having already completed it. Sixty-four percent stated a need for better individual clinical guidance. The majority stated that eight hours every week should be earmarked for formal tuition and research (two hrs clinical tuition, two hrs theory, two hrs supervision in psychotherapy, and two hrs for research). On average, the trainees had used 4200 DKK of their own income and four free days on courses over the previous year. Twenty-four months was proposed as adequate for an introductory appointment. The majority held that appointments should be made on the basis of the traditional curriculum vitae (82%) and a personal interview (86%), while about 20% believed that written or oral references should also be a requirement. Sixty-nine percent believed that selection of applicants for teaching appointments should be made locally with central supervision. Twenty-six percent felt they had been passed over in appointment situations, and 68% claimed it was due to nepotism. Recommendations for modifications of the future postgraduate training according to the responses are proposed, and it is concluded that earmarked resources are necessary, if the intention in the educational reform now in progress is to be realized.

Adult↗

PubMed1993

Determination of chromium in blood and serum: evaluation of quality control procedures and estimation of reference values in Danish subjects.

This paper describes analytical methods to estimate environmental and occupational exposure levels of chromium in blood and serum by Zeeman atomic absorption spectrometry. Also reported is an internal quality control procedure involving a combination of an online quality control and subsequent statistical evaluation of the quality control results to evaluate the performance of the analytical methods. The solubilization of the blood by the proteinase Subtilisin A resulted in a recovery of chromium of 106 +/- 4.5%; the uncertainty was approximately 10% at a chromium level of 1 microgram l-1. The detection limit (LOD) for chromium in serum was 0.17 micrograms l-1 and 0.20 micrograms l-1 for chromium in blood. The LODs were sufficiently low for the determination of chromium in a large fraction of reference populations not occupationally exposed. The present study indicates that reference values for chromium in blood and serum are low but within the range in recent investigations, i.e. 0.04-0.35 micrograms l-1 in serum and 0.12-0.34 micrograms l-1 in human whole blood. The fraction of reference values below LOD was between 0.45 and 0.57 for chromium in serum and blood. Consequently, the reference populations were described by distribution free one-sided tolerance intervals and the precision of the estimation of the tolerance intervals was expressed as coverage intervals. The 95% one-sided tolerance limit calculated for chromium in serum was 0.60 micrograms l-1 with the coverage interval (95 +/- 4.8) percent at a probability of 0.95. Thus, the probability was 0.975 that the tolerance interval covers at least 90.2% of the distribution. In addition, the probability was 0.025 that the tolerance interval covers more than 99.8% of the population. It was only possible to calculate the 90% tolerance interval for chromium in blood with the coverage interval at 0.90 probability. The one-sided tolerance interval for chromium in blood was 0.37 micrograms l-1 with the coverage interval (90 +/- 9.9) percent at a probability of 0.90.

Chromium↗

PubMed1993

The effect of indomethacin infusion on renal hemodynamics and on the renin-angiotensin system during unilateral ureteral obstruction of the pig.

Obstruction of the urinary tract is associated with an increase in pelvic pressure (PP) and a decline in ipsilateral renal blood flow (RBF). To investigate the influence of the renal prostaglandins on these parameters, pigs with complete unilateral ureteral obstruction (UUO) were studied under general anesthesia after administration of indomethacin 30 minutes before obstruction. Pelvic pressure increased to a maximum of 41.1 +/- 2.4 cm. H2O after 6 hours, but maximum pressure, as well as the rate of pressure increase, was significantly reduced after indomethacin. A transient but significant increase in mean aortic blood pressure was seen, together with a bilateral decrease in RBF immediately after indomethacin administration. Ipsilaterally RBF decreased by 25% from 319 +/- 21 ml. per minute to 237 +/- 16 ml. per minute and contralaterally by 23% from 300 +/- 20 ml. per minute to 231 +/- 25 ml. per minute. After 15 hours a further decline was measured in ipsilateral RBF to 136 +/- 20 ml. per minute but, on the contralateral side, RBF was only slightly reduced to 281 +/- 36 ml. per minute after 15 hours. Following indomethacin a sustained increase in ipsilateral renal vascular resistance (RVR) was observed from 37.6 +/- 3.6 mm. Hg x ml.-1 x min. x gm. to 130.5 +/- 42.3 mm. Hg x ml.-1 x min. x gm. compared with a much smaller increase from 37.4 +/- 3.2 mm. Hg x ml.-1 x min. x gm. to 55.1 +/- 9.2 mm. Hg x ml.-1 x min. x gm. in the control group. Renal secretion rate of angiotensin II was significantly reduced 2 and 6 hours after indomethacin administration on the obstructed side, and was not significantly changed on the contralateral side. It can be concluded that inhibition of prostaglandin synthesis during unilateral ureteral obstruction in pigs results in reduced pelvic pressure, renal blood flow and angiotensin II secretion rate from the affected kidney, and that renal prostaglandin synthesis plays an important role for the perfusion of the kidney during ureteral obstruction.

Analysis of Variance↗