Search PubMed⌕ Search

Biomedical subjects

R Andersen

Publications and source records attributed to R Andersen.

At least 55 records · Page 3Linked to original sources
PubMed1996

The X-ray contrast medium iodixanol detects increased colonic permeability equally well as 51Cr-labeled ethylenediaminetetraacetic acid in experimental colitis of rats.

BACKGROUND: Non-ionic, water-soluble radiographic contrast media have been suggested as intestinal permeability probes. We studied the permeability of the isosmolar contrast medium iodixanol and 51Cr-labeled ethylenediaminetetraacetic acid (EDTA) from the non-perforated colon after induction of colonic inflammation. METHODS: Colonic inflammation and ulcerations were induced by luminal colonic instillation of trinitrobenzenesulfonic acid, dissolved in 40% ethanol. Controls received saline. Fourteen days later iodixanol, 320 mg I/ml, and 51Cr-EDTA were given as an enema. Urine was collected for the subsequent 6 h and subjected to high-performance liquid chromatography and gamma activity counting. RESULTS: Urinary recovery of iodixanol and 51Cr-EDTA increased gradually with severity of the colonic inflammation. The correlation between iodixanol and 51Cr-EDTA recovery was strong (corr.coeff = 0.97). CONCLUSIONS: Iodixanol shows as good properties as 51Cr-EDTA when used as intestinal permeability probe in the inflamed and ulcerated rat colon. Use of the radiopaque properties of iodixanol enable intestinal probe exposure registration by film or fluoroscopy.

Animals↗
PubMed1995

Local delivery of indomethacin by a polyorthoester inhibits reossification of experimental bone defects.

Inhibition of orthotopic reossification after surgical removal of bone is sometimes indicated and may be accomplished by implantation of interpositional materials or by systemic administration of indomethacin. However, implantation of nonresorbable foreign material may induce a chronic inflammation and predispose to infections; and systemic administration of indomethacin may induce systemic adverse effects. We studied the effect of local delivery of indomethacin by a bioerodible polyorthoester on the reossification of segmental defects of the radius in rats. We divided 45 Wistar rats into three groups, A-C. A 3.5 mm-long middiaphyseal osteoperiosteal resection of the right radius was made in each rat. The defect was filled with 15 mg of polyorthoester with 5% indomethacin in group A and 15 mg of polyorthoester without drug in group B. No material was implanted in the defects in the group C rats. The rats were killed 50 days postoperatively. The mean area of the residual defects were greater in the defects with the polyorthoester with 5% indomethacin compared with defects with polyorthoester without drug or without implant as judged by computer-assisted area measurements on radiographs. By light microscopy, no inflammation was seen and only traces of the polyorthoester could be detected in the defects filled with the polyorthoester with or without indomethacin. The results of this study suggest that the polyorthoester may be used as a bioerodible system for local delivery of indomethacin to inhibit reossification of skeletal defects without tissue reaction, unabsorbed carrier, or systemic effects.

Animals↗
PubMed1995

Associations between adverse perinatal outcome and serially obtained second- and third-trimester maternal serum alpha-fetoprotein measurements.

OBJECTIVE: Our purpose was to determine whether third-trimester maternal serum alpha-fetoprotein predicts adverse perinatal outcome and whether use of both second- and third-trimester maternal serum alpha-fetoprotein enhances the positive predictive value for various abnormal outcomes. STUDY DESIGN: A cohort study with obstetric outcome assessed by chart analysis after delivery was performed at Regional Medical Center (Memphis, Tennessee), a hospital staffed by university-based physicians serving a large urban population with many indigent patients. A total of 650 women attending prenatal clinics in the above setting with a singleton pregnancy without a neural tube defect, contributing a maternal blood samples in both the second and third trimesters, and delivered in the above hospital participated. Various pregnancy outcomes were correlated with maternal serum alpha-fetoprotein levels in the second and third trimesters and in both. RESULTS: In the third trimester no significant associations were found between maternal serum alpha-fetoprotein elevations and pregnancy complications. In the second trimester elevation ( > or = 2.0 multiples of the median) were, by contrast, significantly associated with preterm premature rupture of the membranes, preterm birth, and low birth weight. No association was found with certain other complications. When second-trimester data were grouped according to the types of complications occurring in individual women, only preterm premature rupture of the membrane proved statistically significant. CONCLUSIONS: Second-trimester but not third-trimester maternal serum alpha-fetoprotein is significantly elevated with preterm premature rupture of the membranes, preterm birth, and low birth weight; in this cohort study no association was found with preeclampsia, oligohydramnios, or polyhydramnios.

Cohort Studies↗
PubMed1995

Intestinal permeability measurements - a new application for water soluble contrast media?

The detection and quantification of altered intestinal barrier function (intestinal permeability) have been addressed frequently during the last year, but the tests available for determination of intestinal permeability are both flawed and have limitations. The new water-soluble roentgen contrast media (CM) of low- and iso-osmolar type have been proposed as intestinal permeability probes. In this article this possible new application for water-soluble CM is discussed in terms of their inherent properties and the experimental and clinical results obtained so far. The 2 iso-osmolar dimers, iodixanol (Visipaque) and iotrolan (Isovist), seem to be as good as the well-documented radio-labeled permeability probe (51)Cr-EDTA in detecting injury of the intestinal mucosal barrier. The CM offer the advantage of allowing direct control of bowel wall exposure with the aid of fluoroscopy. Current permeability probes lack this quality. Iodine-containing substances may be analyzed by the rapid, simple and reliable X-ray fluorescence technique, which is suitable for application in routine clinical practice. We conclude that the new water-soluble roentgen CM have properties which may be of use in the diagnosis and quantification of altered intestinal barrier function.

Animals↗
PubMed1995

Increased intestinal permeability for the isosmolar contrast medium iodixanol during small-bowel ischaemia in rats.

BACKGROUND: Intestinal ischaemia may be difficult to recognize in the early stages. Increased urinary recovery of water-soluble contrast medium during and intestinal follow-through has been suggested as a sign of bowel ischaemia. METHODS: Urinary excretion of the isosmolar water-soluble X-ray contrast medium iodixanol was measured after instillation via an orogastric tube in 56 rats with occlusion of the mesenteric blood vessels. RESULTS: Mesenteric venous occlusion caused only minor histologic alterations of the mucosa. High-performance liquid chromatography (HPLC) and X-ray fluorescence analysis measured urinary iodixanol concentrations 10 and 13 times higher than in the groups with mesenteric arterial occlusion than in controls (p < 0.001), and 3 and 4 times higher than in the group with venous occlusion (p < or = 0.05). Correlation between HPLC and X-ray fluorescence measurements of contrast medium in urine was strong (r = 0.98). CONCLUSION: Measuring urinary contrast medium levels during intestinal follow-through may aid in distinguishing bowel ischaemia following mesenteric arterial occlusion from mesenteric venous occlusion and from the normal bowel.

Animals↗
PubMed1995

Computed vs. film-screen magnification radiography of fingers in hyperparathyroidism. An ROC analysis.

One hundred randomly selected patients with suspected or known hyperparathyroidism were examined in a prospective study of the 2nd and 3rd fingers with film-screen and digital luminescence radiographs using magnification technique. The digital images were displayed on a work-station and printed as hard-copies. Two radiologists evaluated the film-screen images regarding subperiosteal and intracortical resorption and their results were defined as "gold standard" regarding the absence or presence of these changes. Four radiologists evaluated these changes in the 3 image forms and an ROC analysis was performed. Comparing the areas under the ROC curves no significant difference was found between the film-screen images and the 2 digital display forms. These results suggest that currently available digital systems provide adequate diagnostic accuracy for evaluation of subtle skeletal changes.

Adolescent↗
PubMed1995

Munchausen syndrome by proxy: a profile for medical child abuse.

The term Munchausen Syndrome by Proxy describes a pattern of physical abuse in which a perpetrator produces or fabricates illness in a victim. Victims are almost always children. We alternatively call this behaviour medical child abuse. Our report describes five recent cases. Two presented with infantile apnoea, one with alleged hypoventilation, one with recurrent vomiting and one with recurrent infections. Three of the perpetrators were mothers, two were fathers. In three cases diagnoses were confirmed by covert video surveillance. Contrary to popular beliefs, this behaviour is not rare and is not a syndrome of any known psychopathology. It is simply another, very dangerous, form of child abuse. Reported victim mortalities range from 9% to 31%. To ensure child safety we suggest the medical, legal and law enforcement communities begin to view this entity more as a profile of criminal abusive behaviour and less as a medical syndrome.

Adult↗
PubMed1994

Import of the barley PSI-F subunit into the thylakoid lumen of isolated chloroplasts.

A full-length cDNA clone encoding the PSI-F subunit of barley photosystem I has been isolated and sequenced. The open reading frame encodes a precursor polypeptide with a deduced molecular mass of 24837 Da. The barley PSI-F precursor contains a bipartite presequence with characteristics similar to the presequences of proteins destined to the thylakoid lumen. In vitro import studies demonstrate that an in vitro synthesized precursor is transported across the chloroplast envelope and directed to the thylakoid membrane, where it accumulates in a protease-resistant form. Incubation of the precursor with a chloroplast stromal extract results in processing to a form intermediate in size between the precursor and mature forms. Hydrophobicity analysis of the barley PSI-F protein reveals a hydrophobic region predicted to be a membrane spanning alpha-helix. The hydrophobic nature of PSI-F combined with a bipartite presequence is unusual. We postulate that the second domain in the bipartite presequence of the PSI-F precursor proteins is required to ensure the proper orientation of PSI-F in the thylakoid membrane. The expression of the PsaF gene is light-induced similar to other barley photosystem I genes.

Amino Acid Sequence↗
PubMed1994

A comparative study of patient satisfaction with health care in Japan and the United States.

Patient satisfaction with medical care received at selected medical facilities in the United States (895 patients) and in Japan (856 patients) was compared using self-administered questionnaires. In each country, patients at a large government hospital and a smaller affiliated clinic were surveyed. Patients responded to questions concerning specific aspects of medical care, general satisfaction with the care received, waiting time to see the physician and time spent with the physician. Results suggest that patients at study sites in both countries were generally satisfied with the medical care they received. However, American patients were more likely to report satisfaction than their Japanese counterparts on each dimension of health care measured. The largest discrepancies were found in satisfaction with waiting time to see the doctor and time spent with the doctor. Stepwise discriminant analyses indicated that provider skill may be the most important predictor of overall satisfaction with medical care in both countries. These results are discussed in the framework of the underlying health care system.

Adult↗
PubMed1993

The non-NMDA glutamate receptor antagonist GYKI 52466 counteracts locomotor stimulation and anticataleptic activity induced by the NMDA antagonist dizocilpine.

The effects of the non-NMDA glutamate receptor antagonist GYKI 52466 (2.4 and 4.8 mg/kg, i.p.) on spontaneous locomotor activity and haloperidol-induced catalepsy (0.5 mg/kg, i.p.) were assessed in naive rats and in rats pretreated with the NMDA antagonist dizocilpine (0.08 mg/kg, i.p.). GYKI 52466 given alone did not alter locomotor activity and haloperidol-induced catalepsy, but significantly antagonized the dizocilpine-induced locomotor stimulation and counteracted the anti-cataleptic effects of dizocilpine on haloperidol-induced catalepsy. Thus blockade of non-NMDA glutamate receptors antagonized the behavioural stimulant effects of a NMDA receptor blockade.

Animals↗
PubMed1992

Different features of the MHC class I heterodimer have evolved at different rates. Chicken B-F and beta 2-microglobulin sequences reveal invariant surface residues.

Chicken beta 2-microglobulin (beta 2m) and class I (B-F19 alpha chain) cDNA clones were isolated and the sequences compared to those of B-F Ag isolated from chicken E. These clones represent the major expressed class I molecules on E, with B-F alpha size variants evidently due to alternative use of small exons in the cytoplasmic region. The cDNA sequences were compared to turkey beta 2m, the apparent allele B-F12 alpha and other vertebrate homologs, using the 2.6 A structure of the human HLA-A2 molecule as a model. Both chicken alpha 1 and alpha 2 domains resemble mammalian classical class I molecules and the MHC-encoded nonclassical molecules more than CD1 or the class I-like FcR. In contrast, the chicken alpha 3 domain is equally homologous to all alpha 3 domains, to beta 2m and to class II beta 2 domains. For each pair of extracellular domains (alpha 1 vs alpha 2, alpha 3 vs beta 2m), the level of sequence homology between mammalian and avian molecules is quite different. This suggests that the structurally homologous domains have been under different selective pressures during evolution. There is a very strong G + C bias in alpha 3 and beta 2m, leading to an overall change in amino acid composition in B-F compared to class I molecules from other taxa. Many of the surface residues are quite diverged, particularly in alpha 3 and beta 2m. There are fewer changes in intra- and interdomain contact sites. Some residues with important functions are invariant, including seven residues that bind the ends of the peptide, two residues that bind CD8, and three residues that are phosphorylated. The positions of the allelic residues are conserved. There are other patches of invariant residues on alpha 1, alpha 2, and beta 2m; these might bind TCR or other molecules involved in class I function.

Amino Acid Sequence↗
PubMed1992

Experimental colonic inflammation and ulceration. Permeation of a water-soluble contrast medium as a measure of 'disease' activity.

The aim of this study was to investigate the permeation of an isosmolar water-soluble X-ray contrast medium (CM) from the unperforated colon after experimental induction of inflammation and ulceration. One hundred and sixty-five male rats were included. In 110 rats 0.25 ml of 40% ethanol + 15 mg or 30 mg trinitrobenzene (TNB) was instilled into the colon, 7-9 cm proximal to the anus, inducing different degrees of inflammation. Fifty-five rats served as controls and had 0.25 ml saline instilled with the same procedure. At 7, 14, 21, and 28 days 3 ml of the non-ionic CM iodixanol was applied as an enema, and subsequently all urine was collected for the next 4 h. High-performance liquid chromatography analyses of the urine showed a positive relation between the severity of inflammation/ulceration in the colonic wall as assessed by a macroscopic damage score and the amount of CM excreted in the urine. Water-soluble contrast media may have prospects of combining functional tests of intestinal membrane dysfunction with segmental exposure control.

Animals↗
PubMed1992

The effect of a composite of polyorthoester and demineralized bone on the healing of large segmental defects of the radius in rats.

The effect of a composite of demineralized bone mixed with polyorthoester on the healing of large segmental defects in the rat radius was studied. Sixty male Wistar rats were divided into four groups, A through D, and an osteoperiosteal diaphyseal defect of 50 per cent of the length of the bone was made in the right radius of each rat. In Group A, the defect was filled with polyorthoester and demineralized bone; in Group B, demineralized bone; and in Group C, polyorthoester. No material was implanted in the defects in the Group-D rats. The rats were killed fifty days postoperatively. The formation of bone in the defects was quantified with computer-assisted measurements of the area on radiographs. The host-tissue response was evaluated with light microscopy. Defects that had been filled with the composite of polyorthoester and demineralized bone or with demineralized bone alone showed regeneration of bone corresponding to 93.6 and 77.6 per cent of the area of the defect, respectively. Defects that had no implant or that had been filled with polyorthoester alone showed significantly less formation of bone. No inflammation was seen with light microscopy, and only traces of the polyorthoester could be detected in the defects that had been filled with the composite or with polyorthoester alone.

Animals↗