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Biomedical subjects

M Rasmussen

Publications and source records attributed to M Rasmussen.

At least 19 recordsLinked to original sources
PubMed2000

Pulmonary function affects the quantification of rCBF by non-invasive xenon methods.

Estimates of regional cerebral blood flow (rCBF) by non-invasive xenon methods (133-xenon inhalation, xenon-enhanced computed tomography (Xe/CT) and 133-xenon iv injection) are frequently applied in the diagnosis and evaluation of patients suffering from diseases which cause disturbances in the cerebrovascular circulation. These methods all depend on an estimate of the arterial xenon concentration curve derived non-invasively from measurements of the end-tidal xenon concentration curve and used as brain input function in the Kety equation. We have studied the influence of impaired pulmonary gas exchange on the end-tidal and arterial xenon concentration curves in nine anaesthetized pigs by simultaneously measurements of both the end-tidal xenon and arterial xenon concentration curves. Computer simulations were performed to determine the deviations in the calculated rCBF values when using the end-tidal as compared to the arterial xenon concentration curve as brain input function. The results indicated that impairment of the pulmonary gas exchange caused a significant further 'delay' in the arterial xenon concentration curve in comparison to the end-tidal xenon concentration curve. The time constants of arterial curve delay were 11.9 s in the normal pulmonary group, 21 s in the right lung atelectasis group, and 19.7 s in the left pulmonary artery occlusion group. Accordingly, computer simulations indicated a statistically significant 'underestimation' of rCBF due to: (1) pulmonary gas exchange; (2) high or low levels of rCBF; (3) partition coefficient (lambda) of gray and white matter; and (4) xenon inhalation protocols. Our results indicate that quantitative measurements of rCBF by non-invasive xenon methods are markedly affected by deviations between the end-tidal and arterial xenon concentration curve, so that estimates of flow thresholds for infarction are problematic under conditions of impaired pulmonary gas exchange.

Animals↗
PubMed2000

Are cells rescued from 'low density death' by co-operation between phospholipases C AND D?

Cells of the ciliate Tetrahymena thermophila die when transferred at low density to a lipid-free nutritionally complete medium. This death is prevented and they will start to proliferate if protein kinase C is activated and this activation is sustained. We propose that this takes place in two stages. Firstly, the phospholipase C pathway beginning with and specific for phosphatidylinositol leads to the formation of diacylglycerol and inositol tris -phosphate. Diacylglycerol activates protein kinase C, and inositol tris -phosphate via Ca(2+)phospholipase D (PLD). Secondly, the protein kinase C response can now be sustained by diacylglycerol produced by phospholipase D, using phosphatidylcholine and phosphatidylserine as substrates. Should this switching from PI-specific phospholipase C (PLC) to phospholipase D fail, then the cell will die in the course of milliseconds during the minutes following inoculation.

Animals↗
PubMed2000

Virtual temporal bone: creation and application of a new computer-based teaching tool.

The human temporal bone is a 3-dimensionally complex anatomic region with many unique qualities that make anatomic teaching and learning difficult. Current teaching tools have proved only partially adequate for the needs of the aspiring otologic surgeon in learning this anatomy. We used a variety of computerized image processing and reconstruction techniques to reconstruct an anatomically accurate 3-dimensional computer model of the human temporal bone from serial histologic sections. The model is viewed with a specialized visualization system that allows it to be manipulated easily in a stereoscopic virtual environment. The model may then be interactively studied from any viewpoint, greatly simplifying the task of conceptualizing and learning this anatomy. The system also provides for simultaneous computer networking that can bring distant participants into a single shared virtual teaching environment. Future directions of the project are discussed.

Computer Simulation↗
PubMed2000

High-dose rectal and oral acetaminophen in postoperative patients--serum and saliva concentrations.

BACKGROUND: The primary purpose of the study was to examine the absorption of acetaminophen by measuring serum and saliva concentrations produced by a standard postoperative acetaminophen dosing regimen and secondary to examine the correlation between saliva and serum concentrations of acetaminophen after rectal and oral dosing. METHODS: Twenty-four women, aged 18-60 years, scheduled for minor gynaecological laparoscopic surgery were studied. Patients received acetaminophen 2000 mg suppositories after surgery and oral doses of 1000 mg at 4 and 8 h postoperatively. Alfentanil was available via patient-controlled analgesia. Saliva and blood samples were collected postoperatively. RESULTS: At 1, 2, 3, and 4 h after rectal dosing the saliva concentrations (mean+/-SD) were 15.2+/-5.9 micromol/l, 33.7+/-12.5 micromol/l, 45.5+/-19.1 micromol/l, and 55.4+/-23.1 micromol/l, respectively. The serum concentrations at 2 and 4 h were 31.0+/-11.2 micromol/l and 54.8+/-23.8 micromol/l, respectively. Additional oral dosing resulted in saliva concentrations at 5, 8, and 9 h of 99.7+/-49.5 micromol/l, 106.9+/-31.7 micromol/l, and 139.3+/-55.4 micromol/l, respectively, with coincident serum concentrations of 100.1 +/- 50.2 micromol/l, 105.6+/-29.0 micromol/l, and 141.2+/-52.1 micromol/l. After rectal dosing the linear regression resulted in r2=0.96, P<0.001 and saliva/ serum-ratio=0.99. After additional oral dosing the outcome of linear regression was: r2=0.90, P<0.001 and saliva/serum-ratio= 1.00. CONCLUSION: The slow and ongoing absorption process resulting in no maximum concentration within 4 h after administration of 2000 mg acetaminophen suppositories makes this rectal regimen therapeutically irrational for treatment of postoperative pain. The significant ratio and linear correlation between saliva and serum concentrations of acetaminophen suggests that saliva could be used instead of blood to monitor acetaminophen administration in patients.

Absorption↗
PubMed2000

Tropisetron reduces postoperative vomiting in children undergoing tonsillectomy.

In this patient, parent and investigator blinded, randomized, placebo-controlled study, children undergoing tonsillectomy (mean age 6.4 years) received either intravenous placebo (n=36) or tropisetron 0.2 mg.kg-1 up to 5 mg (n=35) at induction of anaesthesia with halothane, nitrous oxide and oxygen. Morphine and paracetamol were given in theatre for postoperative pain. Episodes of vomiting were recorded during the first 24 h after surgery. Intravenous tropisetron was significantly (P<0.001, chi-squared) more effective than placebo in controlling the incidence and frequency of emesis during the first 24 h: vomiting was reduced from 89% to 46% and the mean number of vomits from 4.6 to 2.4. Minor side-effects occurred equally in both the placebo and active groups. Intravenous tropisetron is an effective and safe antiemetic for reducing postoperative vomiting in children undergoing tonsillectomy or adenotonsillectomy.

Anesthesia, Inhalation↗
PubMed2000

Tropisetron plus dexamethasone is more effective than tropisetron alone for the prevention of postoperative nausea and vomiting in children undergoing tonsillectomy.

The 5-HT3 antagonists are effective in reducing postoperative nausea and vomiting (PONV) associated with paediatric tonsillectomy. Although prophylactic tropisetron can reduce the incidence of PONV by half, the resulting level of over 40% is still unacceptably high. The aim of this study was to evaluate the effect of adding dexamethasone to tropisetron. In a blinded study, 59 children (mean age 6.1 years) were administered 0.1 mg.kg-1 up to 2 mg of tropisetron and 66 children (mean age 5.7 years) received the same dose of tropisetron plus 0.5 mg.kg-1 up to 8 mg of dexamethasone. Both drugs were given intravenously during induction of anaesthesia for tonsillectomy. During the inpatient stay of 24 h, the incidence of postoperative vomiting in the tropisetron alone group was 53% compared with 26% in the combination group (P=0.002, chi-squared). A significant reduction in nausea from 53% to 30% was also observed (P=0.02). Parents completed a daily diary for 5 days following discharge. Delayed vomiting occurred in 27% and 11% of the tropisetron and combination therapy groups, respectively (P=0.025) Sixteen percent and 9%, respectively, required medical attention (P=0.27). Tropisetron plus dexamethasone is more effective than tropisetron alone in reducing the incidence of PONV following paediatric tonsillectomy.

Adolescent↗
PubMed2000

Determinants of population changes in fibrinogen and factor VII over 6 years: the Atherosclerosis Risk in Communities (ARIC) Study.

Although numerous cross-sectional studies have identified possible determinants of plasma fibrinogen and factor VII levels, few prospective studies exist. We assessed the longitudinal relation of changes in fibrinogen and factor VII over 6 years with changes to other cardiovascular risk factors in a sample of 440 men and 549 women from the Atherosclerosis Risk in Communities (ARIC) study. Fibrinogen increased more in older participants, those with or who developed diabetes, those who at any time smoked, and those whose plasma HDL cholesterol or triglycerides decreased and increased less in female participants who started hormonal replacement therapy. Factor VII coagulant activity increased more in younger participants, women, those who gained greater weight or developed diabetes, those who quit smoking, those in whom plasma triglycerides decreased, and female participants who received hormonal replacement therapy. Thus, our longitudinal data suggest with some exceptions that adverse changes in cardiovascular risk factors are accompanied by increases in plasma levels of fibrinogen and factor VII.

Aging↗
PubMed2000

The influence of the input function on quantitative rCBF by the Xe/CT method.

Measurements of rCBF by the Xe/CT method are based on the assumption of identity between the end-tidal xenon curve which is applied as input function, and the arterial xenon curve being the true input function to the brain. In this study corresponding end-tidal and arterial xenon curves were measured in an experimental animal model (part 1) and in 5 patients with traumatic brain injury (part 2) and used for rCBF calculation. In both studies rCBF was underestimated by using the end-tidal xenon concentration curve as brain input function. In part 1 rCBF underestimation was depended on pulmonary gas exchange; high or low levels of rCBF; tissue type; and xenon inhalation protocols. In part 2 the mean rCBF underestimation was 18.8 +/- 8.3%. In conclusion, non-invasive estimate of the input function should be considered as a source of error when defining quantitative blood flow values e.g. the flow thresholds of ischaemic infarction.

Animals↗
PubMed1999

Protein GRAB of streptococcus pyogenes regulates proteolysis at the bacterial surface by binding alpha2-macroglobulin.

In the molecular interplay between pathogenic microorganisms and their host, proteolytic mechanisms are believed to play a crucial role. Here we find that the important human pathogen Streptococcus pyogenes (group A Streptococcus) expresses a surface protein with high affinity (Ka = 2.0 x 10(8) M-1) for alpha2-macroglobulin (alpha2M), the dominating proteinase inhibitor of human plasma. The immunoglobulin-binding protein G of group C and G streptococci also contains an alpha2M-binding domain and a gene encoding protein GRAB (protein G-related alpha2M-binding protein) was identified in the S. pyogenes Genome Sequencing data base. The grab gene is present in most S. pyogenes strains and is well conserved. Protein GRAB has typical features of a surface-attached protein of Gram-positive bacteria. It also contains a region homologous to parts of the alpha2M-binding domain of protein G and a variable number of a unique 28-amino acid-long repeat. Using Escherichia coli-produced protein GRAB and synthetic GRAB peptides, the alpha2M-binding region was mapped to the NH2-terminal part of protein GRAB, which is the region with homology to protein G. An isogenic S. pyogenes mutant lacking surface-associated protein GRAB showed no alpha2M binding activity and was attenuated in virulence when injected intraperitoneally in mice. Finally, alpha2M bound to the bacterial surface via protein GRAB was found to entrap and inhibit the activity of both S. pyogenes and host proteinases, thereby protecting important virulence determinants from proteolytic degradation. This regulation of proteolytic activity at the bacterial surface should affect the host-microbe relation during S. pyogenes infections.

Amino Acid Sequence↗
PubMed1999

A tumour in the breast: vaccination granuloma as a differential diagnosis.

AIMS: Breast cancer is the most frequent type of cancer in women; special attention is therefore paid to tumours in the breast region. Vaccination granuloma is a differential diagnosis of tumours in the upper part of the breast. METHODS: All granulomatous lesions in the breast region since 1970 were retrieved from the files of the Departments of Pathology at Odense University Hospital and Svendborg Hospital. RESULTS: Fourteen cases with a histology compatible with vaccination granuloma were found. Eight patients had a known history of tetanus vaccination. The tumours were ovoid, or even rod-shaped, and measured between 8x3 mm and 12x10 mm. Histologically, there were necrotic foci surrounded by histiocytes, lymphocytes, and plasma cells. Aluminium was detected by staining with solochrome azurine. CONCLUSIONS: The possibility of a vaccination granuloma should be kept in mind in patients with a palpable tumour in the upper part of the breast, as well as in mammography screening conditions and in follow-up patients after previous treatment for breast cancer.

Adolescent↗
PubMed1999

Possible advantages and drawbacks of adding flexible sigmoidoscopy to hemoccult-II in screening for colorectal cancer. A randomized study.

BACKGROUND: Flexible sigmoidoscopy (FS) has been recommended as a screening method to reduce mortality from colorectal cancer (CRC). The present study evaluates the effect of adding FS to the fecal occult blood test Hemoccult-II (H-II) on diagnostic yield of colorectal neoplasia. METHODS: A total of 10,978 normal persons aged 50-75 years were invited to participate, 5495 persons being allocated at random to H-II and FS and 5483 to H-II alone. RESULTS: In spite of a lower compliance (40% versus 56%) for the combined procedure, the diagnostic yield of colorectal neoplasia was higher than for H-II alone (12 CRC versus 4 CRC, and 72 large adenomas versus 14). Within 24-62 months after screening there were fewer CRCs detected after H-II + FS than after H-II alone. The stage distribution was less favorable than in screen-detected cases. CONCLUSION: One FS may not be an optimal way of screening, but FS deserves to be evaluated in randomized population studies including repeated H-II tests in the control arm.

Aged↗
PubMed1999

The Virtual Pelvic Floor, a tele-immersive educational environment.

This paper describes the development of the Virtual Pelvic Floor, a new method of teaching the complex anatomy of the pelvic region utilizing virtual reality and advanced networking technology. Virtual reality technology allows improved visualization of three-dimensional structures over conventional media because it supports stereo vision, viewer-centered perspective, large angles of view, and interactivity. Two or more ImmersaDesk systems, drafting table format virtual reality displays, are networked together providing an environment where teacher and students share a high quality three-dimensional anatomical model, and are able to converse, see each other, and to point in three dimensions to indicate areas of interest. This project was realized by the teamwork of surgeons, medical artists and sculptors, computer scientists, and computer visualization experts. It demonstrates the future of virtual reality for surgical education and applications for the Next Generation Internet.

Anatomy↗
PubMed1998

Examination of acetaminophen for outpatient management of postoperative pain in children.

We have examined acetaminophen (paracetamol) dosing for outpatient management of posttonsillectomy pain in children. Forty children, 5-15 years of age, undergoing tonsillectomy and their parents were randomly assigned to use a scheduled administration of acetaminophen in weight appropriate doses, 60 mg.kg-1.24h-1 orally, 90 mg.kg-1.24h-1 rectally, or to use acetaminophen 'as needed' according to present standards (control group). Postoperative pain was assessed by the child using the poker chip tool for the first three days after discharge. The prevalence of pain amongst all the children was high. The second day after discharge 22%-64% of the children in the study group and 36%-73% of the children in the control group rated severe pain. Recommended dose ranges of acetaminophen do not provide sufficient pain relief in children following tonsillectomy. Further studies are required to determine, whether higher doses of acetaminophen or analgesics with different analgesic properties will lead to improved analgesia in children following tonsillectomy.

Acetaminophen↗
PubMed1998

Identification of an insertion sequence located in a region encoding virulence factors of Streptococcus pyogenes.

An insertion sequence, IS1562, was identified in a Streptococcus pyogenes strain of the clinically important M1 serotype. IS1562 is located in the mga regulon between the genes coding for the M protein and the C5a peptidase, both important virulence factors. The same or similar insertion sequences were found in most S. pyogenes strains, but the chromosomal location differed among isolates.

Adhesins, Bacterial↗
PubMed1998

The virtual temporal bone.

The human temporal bone is a 3-dimensionally complex portion of the skull that contains delicate and vital anatomic structures imbedded within dense bone. Current teaching tools have proven to be only marginally adequate for the needs of the aspiring otologic surgeon in learning this anatomy. A variety of image processing and reconstruction techniques were used to reconstruct an anatomically accurate 3-dimensional model of the human temporal bone from serial histologic sections. Using CAVE technology, the model can be manipulated in a stereoscopic virtual environment so that it can be studied from any viewpoint, greatly simplifying the task of learning this anatomy. Applications in surgical planning and Internet based teaching are discussed.

Anatomy↗
PubMed1998

Congenital ptosis and blepharophimosis in a mentally retarded girl: a new case of Ohdo syndrome?

A mentally retarded girl with congenital blepharophimosis, ptosis, hypoplastic teeth and other traits consistent with Ohdo syndrome is reported. Her mother had had surgery for blepharophimosis as a small child, but did not fulfil the other criteria for Ohdo syndrome. The mother had also been abusing alcohol prior to the pregnancy. Differential diagnoses and possible modes of inheritance are discussed.

Abnormalities, Multiple↗
PubMed1998

Arthroscopic removal of palmar/plantar osteochondral fragments (POF) in the metacarpo- and metatarso-phalangeal joints of standardbred trotters--outcome and possible genetic background to POF.

A clinical material of 133 Standardbred horses with palmar/plantar osteochondral fragments (POF) in the metacarpo- and metatarsophalangeal joints were studied. All horses had their fragments removed with arthroscopic surgery. 102 of the horses were 3 years old or younger when surgery was performed. Anatomical localisations of the fragments were in agreement with earlier reports. There was no statistical significant difference in month of birth in the POF--group compared to the total population. Eighty % of the horses that had raced before surgery came back to racing. The racing performance relative to their contemporaries remained the same after the POF operation. 65% of the horses that had not raced before surgery raced after the operation. The breeding index BLUP (Best Linear Unbiased Prediction) was used to evaluate if the POF-horses differed genetically in racing ability from the total population. The average BLUP value of the POF group was 103.4 (+/- 0.65), while the mean BLUP value of the total population was 98.9. This difference was highly significant and indicated that these POF horses belonged to a selected group. A homogeneity test of allele frequencies in blood type systems was performed to evaluate if any genetic difference was persistent between POF horses compared to the total population. The statistical analysis of gene frequencies for alleles in blood type systems indicated a genetic discrimination in blood type systems D and Tf.

Age Factors↗