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Biomedical subjects

L Rasmussen

Publications and source records attributed to L Rasmussen.

At least 37 records · Page 2Linked to original sources
PubMed1998

Geographic and demographic differences in the frequency of human cytomegalovirus gB genotypes 1-4 in immunocompromised patients.

To test the hypothesis that human cytomegalovirus (CMV) gB genotype may differ with geographic origin or patient demographics, CMV DNA was amplified for gB typing from immunocompromised patients in Italy and Africa and compared with previously reported frequencies in California. Increased gB2 frequency occurred in Italian homosexual AIDS patients, as compared with both Italian heterosexual injection drug users with AIDS and heterosexual Zimbabwe AIDS patients. Occurrence of gB3 in Italy was higher in injection drug users than in homosexual AIDS patients. The incidence of gB4 was higher overall in the Italian as compared with the California patients. Therefore geographic and demographic differences in patients affect gB distribution and should be considered before associations of gB genotypes and virulence are made.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Resumption of rapid proliferation from lag phase in cultures of Saccharomyces cerevisiae in poor nutrient conditions. Effect of surface and intracellular signalling mechanisms.

Saccharomyces cerevisiae was inoculated into a dilute synthetic minimal medium with glycerol as the carbon source. The number of live cells in the cultures was determined by colony counts on agar plates. Untreated control cells had doubled in number about once at the end of the first week and had gone through eight doublings by the end of the second week. Addition of either 8-bromo-cyclic guanosine monophosphate (8-bromo-cGMP) or human recombinant insulin, made the cells go through 12 and 10 doublings, respectively, by the end of the first week. In contrast, 8-bromo-cyclic adenosine monophosphate (8-bromo-cAMP) had only slight stimulating effects on cell multiplication, but if it was combined with phorbol-12-myristate-13-acetate (PMA) the cells went through about 12 doublings during the first week. Addition of LY 83583, an inhibitor of soluble guanylate cyclase, prevented cell proliferation. Further addition of 8-bromo-cGMP bypassed this inhibition. Singly, bradykinin or PMA did not affect cell multiplication. However, when these two compounds were combined, the cells went through about 10 doublings during the first week. Neither bradykinin, nor PMA had any releasing effect on the inhibition of LY 83583. These results indicate the existence of several routes leading to cell proliferation in wildtype S. cerevisiae cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1998

Staurosporine-induced cell death in Tetrahymena thermophila has mixed characteristics of both apoptotic and autophagic degeneration.

Staurosporine blocks signal transduction associated with cell survival, proliferation and chemosensory behaviour in the ciliated protozoan, Tetrahymena thermophila. Staurosporine inhibits cell proliferation and in vivo protein phosphorylation induced by phorbol ester. It also reduces the in vitro phosphorylation of the PKC-specific substrate, myelin basic protein fragment 4-14. Our results show that cell death in the presence of staurosporine is associated with morphological and ultrastructural changes similar to both apoptosis and autophagic degeneration, but these in turn can be postponed or prevented by 8-bromo-cyclic GMP, protoporphyrin IX, hemin or actinomycin D, although phorbol ester and insulin were ineffective. The results support the notion that staurosporine-induced cell death is an active process, associated with and/or requiring de novo RNA synthesis.

Animals↗
PubMed1998

Signaling in unicellular eukaryotes.

Aspects of intercellular and intracellular signaling systems in cell survival, proliferation, differentiation, chemosensory behavior, and programmed cell death in free-living unicellular eukaryotes have been reviewed. Comparisons have been made with both bacteria and metazoa. The central organisms were flagellates (Trypanosoma, Leishmania, and Crithidia), slime molds (Dictyostelium), yeast cells (Saccharomyces cerevisiae), and ciliates (Paramecium, Euplotes, and Tetrahymena). There are two novel aspects in this review. First, cellular responses are viewed in an evolutionary perspective, rather than from the more prevailing one, in which the unicellular eukaryotes are seen by the mammalian organisms. Second, results obtained with cell cultures in minimal, chemically defined nutrient media at low cell densities where intercellular signaling is strongly reduced are discussed. These results shed light on control mechanisms and their cooperation inside the living cell. Intracellular systems have many common features in unicellular and multicellular organisms.

Animals↗
PubMed1998

Gingival crevicular fluid from patients with periodontitis contains bone resorbing activity.

Inflammatory processes occurring in the vicinity of bone tissue often result in stimulation of osteoclast activity and loss of skeletal mass. The aim of the current study was to determine if inflammatory exudates collected from gingival pockets in patients with periodontitis contain factors capable of stimulating resorptive activity. The degree of bone mineral mobilization and bone matrix degradation was assessed by analysis of the release of 45Ca and 3H from bones prelabelled with 45CaCl2 and [3H]proline, respectively. Gingival crevicular washings from six patients with signs of periodontitis stimulated 45Ca or 3H release from the calvarial bones. The stimulatory effect of the gingival crevicular washings on 45Ca release was concentration- and time-dependent, and reduced by calcitonin, a specific osteoclast inhibitor. These data demonstrate that crevicular fluid contains factor(s) which can stimulate osteoclastic degradation of bone in vitro. The bone resorbing activity was partially retained after extensive dialysis. Analysis of the concentrations of prostaglandin E2, interleukin-1alpha and interleukin-1beta in the crevicular fluids, and comparisons of these agents as stimulators of 45Ca release in the mouse calvarial assay, suggest that prostaglandin E2 is not the sole factor responsible for the bone resorbing activity of the exudates. The data indicate that other factors, such as IL-1, may play key roles in the stimulation of osteoclastic activity by gingival crevicular washings.

Adolescent↗
PubMed1998

Autocrine/paracrine activator of cell proliferation: purification of a 4-6 kD compound with growth-factor-like effects in Tetrahymena thermophila.

Extracellular medium from cultures of Tetrahymena thermophila was collected, concentrated and fractionated by ultrafiltration and low-pressure column chromatography. The effect on proliferation of various fractions was tested on cultures of T. thermophila in synthetic medium at low initial cell densities (< 250 cells/ml). In unsupplemented cultures, cells failed to thrive and died before proliferation. Addition of the fraction isolated from the extracellular medium in the molecular weight range of 1-10 kD activated the cells to proliferate. The size of the main compound in this fraction, herein referred to as TPAF, was in the range of 4-6 kD as estimated by SDS-PAGE. Evidence of a dialysable factor produced by cells in the stationary phase inhibiting cell proliferation has also been found.

Animals↗
PubMed1998

[Danish contributions to early cell biology: with a point of departure in films, among others about the inauguration of the biological institute of the Carlsberg Foundation October 19, 1932].

Louis Pasteur in France saw that microbes might cause disease, Gerhard Armauer Hansen in Norway established a connection between a bacterium and a human disease, and Robert Koch in Germany supplied the final proof that linked bacteria to disease. From then on there was an explosion in interest and techniques for cultivation of bacteria. It lasted about 30 years before Harrison in the USA succeeded in growing cells from multicellular organisms in pure culture. His technique came to Denmark at an early time point and the Rockefeller Foundation in New York and the Carlsberg Foundation in Copenhagen joined forces and built the Biological Institute of the Carlsberg Foundation in order to support Albert Fischer in his study of cell biology. His first assistant at this Institute, Fritz Lipmann, won the Nobel Prize for 1953 for work initiated there. The Institute remained a center for cell biology for almost 50 years. At the neighboring Rockefeller Institute in Copenhagen Einar Lundsgaard obtained results showing in the short perspective that current concepts of cellular utilization of energy were wrong, and in the long perspective his assistant, Herman Kalckar, would formulate modern concepts of cellular oxidative phosphorylations. This review is based in part on films from the 1930's.

Academies and Institutes↗
PubMed1997

Bovine immunodeficiency virus tat gene: cloning of two distinct cDNAs and identification, characterization, and immunolocalization of the tat gene products.

cDNAs encoding the bovine immunodeficiency virus (BIV) transactivator gene (tat) were cloned from virally infected cells and characterized. BIV expresses two distinct tat mRNAs composed of three exons that are derived by alternative splicing. The BIV tat mRNA splice variants encode Tat proteins of 103 (Tat103) and 108 (Tat108) amino acids. The Tat103 coding region is specified only by exon 2, while that of Tat108 is specified by a truncated exon 2 and the first 30 nt of exon 3. Thus, the first 98 amino acids of each Tat are identical, and have amino terminal, cysteine-rich, conserved core, basic, and carboxyl-terminal domains similar to Tats encoded by primate lentiviruses. BIV-infected bovine cells express a 14-kDa phosphorylated Tat protein identical in size to recombinant Tat expressed in bacteria. BIV Tat was shown to localize exclusively in the nucleoli of virally infected and Tat-expressing cells. Reporter gene assays indicated that Tat103 and Tat108 can strongly transactivate the BIV long terminal repeat (LTR) in virally permissive canine Cf2Th and nonpermissive HeLa and mouse NIH 3T3 cells, but not in permissive lapine EREp cells. However, an intact BIV tat gene is required for viral replication in both Cf2Th and EREp cells. Strong LTR activation by BIV Tat requires a TAR (transactivation responsive) element delimited by viral nt +1 to +31 and the Tat basic domain. BIV Tat strongly cross-transactivates the HIV-1 LTR in a TAR-dependent manner in Cf2Th, but not in EREp, HeLa, or NIH 3T3 cells. In contrast, strong, TAR-dependent cross-transactivation of the BIV LTR by HIV-1 Tat could not be demonstrated in any of these cell types. In Cf2Th cells Tat108 effects a moderately stronger transactivation of the BIV LTR than Tat103, indicative of a functional difference in BIV Tat proteins encoded by the mRNA splice variants. The present studies demonstrate that BIV Tat parallels the primate lentiviral Tats in structure and biochemistry but is not interchangeable with the latter.

3T3 Cells↗
PubMed1997

[Transfusion service of the county of Funen. Organizational and economical aspects of restructuring].

The reorganization of the transfusion service in the County of Funen during the period from 1990 to 1996 is described. The professional responsibility for the transfusion service was delegated to the county's only department with specialists in transfusion medicine. The responsibility for economy and personnel remained decentralized. Standard operation procedures for collection and production of blood components and for blood group serology were standardized resulting in higher quality. The number of collections were reduced from 47,000 to 35,000 in spite of an unchanged number of transfused units (approx. 31,000 per year). The outdating was reduced from 35 to 2%. A computer system was implemented resulting in rationalized flow of work and the introduction of a computer crossmatch. From 1997, when the computer system will have been paid for, the county and the university hospital will gain DKK 1.6 million and DKK 2.0 million per year respectively as a result of the reorganization.

Blood Banks↗
PubMed1997

[Emptying of colon prior to colonoscopy. A comparison between emptying using peroral polyethylene glycol-electrolyte and conventional emptying with dietary restrictions, laxatives and water lavage].

The purpose of the study was to compare the degree of bowel emptying at colonoscopy after preparation with either traditional water enema, dietary restrictions and laxatives or after oral lavage solution (Klean-Prep). Colonoscopy was performed in 104 patients over a two month period, 56 patients being allocated to the conventional preparation and 48 to Klean-Prep. The quality of bowel emptying was evaluated visually during endoscopy and by the proportion of incomplete colonoscopies. Bowel emptying was less satisfactory after Klean-Prep (p = 0.018) and seven incomplete colonoscopies resulted in contrast to two after conventional preparation. The results were obtained from a surgical department with a permanent small staff of motivated nurses preparing a huge number of patients for colonoscopy. No economic advantages could be demonstrated by the use of Klean-Prep.

Administration, Oral↗
PubMed1997

Progress in an ecotoxicological standard protocol with protozoa: results from a pilot ring test with Tetrahymena pyriformis.

The aim of this project was to develop a standardized multigeneration growth inhibition test protocol to assess the sublethal effects of industrial chemicals and pesticides on protozoans. The inclusion of a test with protozoa would be an ecologically relevant supplement to the existing basic set in aquatic toxicity testing. The different aspects evaluated in the pilot ring study include: two media, two volumes, two end points and two different methods to measure the cell density. Taking into account the aim to develop a simple, sensitive, reproducible and cost effective test, recommendations are made for a standardized protocol.

1-Octanol↗
PubMed1997

Temperature acclimation of Trypanosoma cruzi epimastigote and metacyclic trypomastigote lipids.

This study examines the changes in cellular lipids that take place when Trypanosoma cruzi epimastigotes and metacyclic trypomastigotes are transferred from 28 to 37 degrees C. We found a rise in the sterol to phospholipid ratio, as well as in the triacylglycerol and steryl ester cellular content in T. cruzi epimastigotes. In addition, saturated to unsaturated fatty acid ratios in phospholipids increase. This latter effect appears to be due to two concurrent processes. Firstly, fatty acyl delta9 and, especially, delta12 desaturations are significantly diminished at 37 degrees C. Secondly, triacylglycerols and steryl esters undergo changes in their fatty acyl composition opposite to those simultaneously observed in phospholipids, i.e. the ratio of saturated to unsaturated fatty acids markedly decreases. Similar alterations in each of the lipid classes and in the fatty acid composition of polar and neutral lipids were found in cultured metacyclic trypomastigotes on exposure to the same shift-up. These observations suggest that a global remodeling of cellular lipids that involves extensive fatty acid exchange between neutral and polar lipid pools represents a novel and important mechanism of adaptation of the parasites to the temperature changes they encounter in their life cycle.

Adaptation, Physiological↗
PubMed1997

Risk for retinitis in patients with AIDS can be assessed by quantitation of threshold levels of cytomegalovirus DNA burden in blood.

Cytomegalovirus (CMV) retinitis in patients infected with human immunodeficiency virus (HIV) is a significant clinical problem. Seventy-five patients with CD4 T cell counts <100/mm3 were monitored prospectively every 2 months for CMV DNA burden. The target for DNA amplification was a 162-bp fragment from the CMV immediate early gene. CMV DNA burden, at levels of > or =320 in white blood cells or > or =32 in plasma (P = .001), particularly when sustained (P = .005 and .008, respectively), distinguished patients who developed retinitis from those who remained free of disease. Progression to retinitis was not consistently accompanied by increases in CMV burden, indicating that quantitation of CMV burden beyond threshold levels is not necessary to predict risk for development of retinitis. Virus isolation from WBC, but not urine, was also significantly associated with risk for retinitis (P = .001).

Acquired Immunodeficiency Syndrome↗
PubMed1997

Cytomegalovirus gB genotype distribution differs in human immunodeficiency virus-infected patients and immunocompromised allograft recipients.

Cytomegalovirus isolates can be grouped into 4 gB and 2 gH genotypes. gB genotypes were studied in patients infected with human immunodeficiency virus (HIV) and in allograft transplantation recipients. In allograft recipients, the distribution of gB 1, -2, -3, and -4 in leukocytes and urine, respectively, was 36%, 21%, 43%, and 0% and 39%, 30%, 17%, and 13%. However, in leukocytes of HIV-infected patients with <100/microL CD4 cells, gB1 was found significantly less often than in allograft recipients (11% vs. 36%) but gB2 was more frequent (56% vs. 21%; P < .05). The decreased incidence of gBl and increased incidence of gB2 compared with allograft recipients was also seen in urine of HIV-infected patients and reflected the distribution seen in leukocytes. gB4 was found significantly more often (P < .05) in semen than in leukocytes of HIV-infected patients with < 100/microL CD4 cells. gB1-4 genotypes were similar in patients with < 100/microL CD4 cells with or without retinitis.

AIDS-Related Opportunistic Infections↗
PubMed1997

Efficacy of a pectin-based anti-reflux agent on acid reflux and recurrence of symptoms and oesophagitis in gastro-oesophageal reflux disease.

OBJECTIVE: Gastro-oesophageal reflux disease may be treated with a drug forming a floating neutral raft in the stomach. The pectin-based raft-forming anti-reflux agent Aflurax (Idoflux) was examined, first regarding reduction of oesophageal acid exposure, and next as to its efficacy as maintenance treatment in patients with healed oesophagitis. DESIGN: Double-blind, placebo-controlled randomized clinical trials. SETTING: Open access endoscopy unit. PARTICIPANTS: Fourteen patients with erosive oesophagitis had measurement of acid exposure. Eighty-eight patients with healed erosive/ulcerative oesophagitis and relief of heartburn after pre-treatment with omeprazole received maintenance treatment. INTERVENTIONS: Crossover 12-h oesophageal pH monitoring during Aflurax/placebo treatment. Maintenance treatment for up to 6 months with two tablets of Aflurax 1200 mg or placebo four times daily. MAIN OUTCOME MEASURES: Percentage time pH less than 4 in 6 plus 6 h (upright + supine). Time to recurrence of moderate or severe heartburn (life table analysis). RESULTS: The median (interquartile range) acid exposure times in the upright position were: 3.1% (1.6-13.0%) on Aflurax versus 6.7% (2.5-14.9%) on placebo (P = 0.10). In the supine position no difference was found (Aflurax 13.7%, placebo 13.2%). The time to recurrence of heartburn with Aflurax treatment was prolonged significantly; after 6 months the life table estimates were 48% of patients in remission on Aflurax versus 8% on placebo (P = 0.01). Following treatment, erosive oesophagitis was found in 17/34 on Aflurax versus 28/38 on placebo (P < 0.05). CONCLUSION: Aflurax significantly delays recurrence of moderate or severe heartburn and erosive oesophagitis, when used as maintenance treatment. The acid exposure was not significantly reduced with pH monitoring.

Aged↗
PubMed1997

The human cytomegalovirus UL55 (gB) and UL75 (gH) glycoprotein ligands initiate the rapid activation of Sp1 and NF-kappaB during infection.

The cellular transcription factors Sp1 and NF-kappaB were upregulated shortly after the binding of purified live or UV-inactivated human cytomegalovirus (HCMV) to the cell surface. The rapid time frame of transcription factor induction is similar to that seen in other systems in which cellular factors are induced following receptor-ligand engagement. This similarity suggested that a cellular receptor-viral ligand interaction might be involved in Sp1 and NF-kappaB activation during the earliest stages of HCMV infection. To focus on the possible role viral ligands play in initiating cellular events following infection, we first used purified viral membrane extracts to demonstrate that constituents on the membrane are responsible for cellular activation. Additionally, these studies showed, through the use of neutralizing antibodies, that the viral membrane mediators of this activation are the major envelope glycoproteins gB (UL55) and gH (UL75). To confirm these results, neutralizing anti-gB and -gH antibodies were used to block the interactions of these glycoproteins on whole purified virus with their cell surface receptors. In so doing, we found that Sp1 and NF-kappaB induction was inhibited. Lastly, through the use of purified viral gB protein and an anti-idiotypic antibody that mimics the image of the viral gH protein, it was found that the engagement of individual viral ligands with their appropriate cell surface receptors was sufficient to activate cellular Sp1 and NF-kappaB. These results support our hypothesis that HCMV glycoproteins mediate an initial signal transduction pathway which leads to the upregulation of host cell transcription factors and suggests a model wherein the orderly sequence of virus-mediated changes in cellular activation initiates with viral binding via envelope glycoproteins to the cognate cellular receptor(s).

Antibodies, Anti-Idiotypic↗