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Biomedical subjects

H Nielsen

Publications and source records attributed to H Nielsen.

At least 19 recordsLinked to original sources
PubMed1992

Structural organization of the genes encoding the small nuclear RNAs U1 to U6 of Tetrahymena thermophila is very similar to that of plant small nuclear RNA genes.

We report the sequences of the genes encoding the small nuclear RNAs (snRNAs) U1 to U6 of the ciliate Tetrahymena thermophila. The genes of the individual snRNAs exist in two to six slightly different copies per haploid genome. Sequence analyses of the gene-flanking regions indicate that there are two classes of snRNA genes. Both classes are characterized by several conserved sequence elements, some of which are unique to each class and some of which are found in both classes. Comparison of the promoter structure of the snRNA genes of T. thermophila with the promoter structures of snRNA genes of other organisms revealed several similarities to plant snRNA genes. These similarities include the overall promoter architecture as well as specific sequence elements. The structural organization of the 3' flanking region of some of the T. thermophila snRNA genes is not observed in other organisms. This finding is discussed in relation to a possible role in snRNA 3'-end formation.

Animals↗
PubMed1992

A novel class of nucleolar RNAs from Tetrahymena.

We describe a family of at least four nucleolar RNAs (snoRNAs) from the ciliate, Tetrahymena. The snoRNAs are 120-140 nucleotides long, moderately AU-rich and contain no modified nucleotides. Their 5' ends are blocked by a cap of unknown nature. The snoRNAs can be folded into similar secondary structures consisting of two hairpins separated by a single-stranded AU-rich spacer. The sequences and secondary structures show no extensive sequence or secondary structure resemblance to any other small RNAs in the public databases.

Animals↗
PubMed1992

[Angiofollicular lymph node hyperplasia (Castleman disease)].

Angiofollicular lymph node hyperplasia (Castleman's disease) is a relatively rare disease of differential diagnostic interest in patients with lymphadenopathy. The etiology and pathogenesis are still not elucidated. The disease is classified into localized and systemic types. The localized form is divided histologically into hyaline-vascular type and plasma cell types. The former is usually demonstrated incidentally as a widening of the mediastinum in otherwise asymptomatic patients. The plasma cell type usually presents in the abdominal lymph nodes and is accompanied by fever, loss of weight, anemia and hypergammaglobulinemia. Surgical treatment is curative in the localized disease. The systemic disease involves multiple lymph nodes, and multiple organs are affected. The prognosis is dubious, and frequently the patients rapidly die from septicemia or other infectious complications. Some patients develop malignancies. Treatment with glucocorticosteroids and chemotherapy has only demonstrated a limited effect. The diagnosis requires both a characteristic histopathology and typical clinical symptoms. A current illustrative case report is presented.

Castleman Disease↗
PubMed1992

Inheritance of the group I rDNA intron in Tetrahymena pigmentosa.

We have previously argued from phylogenetic sequence data that the group I intron in the rRNA genes of Tetrahymena was acquired by different Tetrahymena species at different times during evolution. We have now approached the question of intron mobility experimentally by crossing intron+ and intron- strains looking for a strong polarity in the inheritance of the intron (intron homing). Based on the genetic analysis we find that the intron in T. pigmentosa is inherited as a neutral character and that intron+ and intron- alleles segregate in a Mendelian fashion with no sign of intron homing. In an analysis of vegetatively growing cells containing intron+ and intron- rDNA, initially in the same macronucleus, we similarly find no evidence of intron homing. During the course of this work, we observed to our surprise that progeny clones from some crosses contained three types of rDNA. One possible explanation is that T. pigmentosa has two rdn loci in contrast to the single locus found in T. thermophila. Some of the progeny clones from the genetic analysis were expanded for several hundred generations, and allelic assortment of the rDNA was demonstrated by subcloning analysis.

Alleles↗
PubMed1992

Defective monocyte oxidative metabolism in a child with Smith-Lemli-Opitz syndrome.

We present a patient with Smith-Lemli-Opitz syndrome with immunodeficiency. The patient suffered numerous infectious episodes, atopic dermatitis and wheezing. Immunological investigations demonstrated severely reduced oxidative burst-responsiveness of the blood monocytes, whereas chemotaxis, phagocytosis and interleukin-1 production were normal. Tests of neutrophils and lymphocytes were normal excluding previously described immune deficiency disorders. The father proved to have diminished monocyte oxidative metabolism as well, whereas the mother had normal monocyte function. The genetic and immunological aspects are discussed in relation to the syndrome.

Abnormalities, Multiple↗
PubMed1992

Activation of human phagocyte oxidative metabolism by Helicobacter pylori.

A characteristic feature of chronic antral gastritis is the abundant inflammatory response in close association with Helicobacter pylori, but the immunopathological mechanisms of tissue damage are unknown. Because reactive oxygen radicals have been implicated in the tissue damage of other chronic inflammatory disorders, we investigated the potential ability of H. pylori sonicate to influence the oxidative burst responsiveness of human polymorphonuclear leukocytes and monocytes. For both cell types, a dose-dependent stimulation in a chemiluminescence system was observed. Furthermore, preincubation in sonicate caused a marked priming of the cells to subsequent stimulation with the oligopeptide N-f-methionyl-leucyl-phenylalanine and phorbol-myristate-acetate. The sonicate activity was nondialysable, completely destroyed by proteinase and resistant to heat treatment. However, dialysis of boiled sonicate significantly reduced the activity, suggesting the breakdown of a larger molecule(s) to smaller fragments still biologically active. Preliminary experiments suggest that the activity is 25-35 kilodaltons. The demonstration of a protein with stimulatory activity for production of reactive oxygen radicals by human phagocytes may contribute to the understanding of the immunopathology associated with H. pylori infection.

Adult↗
PubMed1992

Specific opsonic activity for staphylococci in peritoneal dialysis effluent during continuous ambulatory peritoneal dialysis.

In a prospective study of intraperitoneal opsonins in 30 patients undergoing continuous ambulatory peritoneal dialysis (CAPD), the IgG concentration, the fibronectin concentration, the specific antistaphylococcal antibody level, and the opsonic activity against Staphylococcus epidermidis were measured in peritoneal dialysis effluent from the initiation of CAPD and monthly for 6 months. Significant correlation was found between the four assays, but the interindividual and intraindividual variations were considerable. No statistically significant correlation was observed between susceptibility of the patients to CAPD-related infectious peritonitis and any of the above-mentioned parameters of humoral defense. We conclude that at the present time it is not feasible to use these assays for the establishment of prognosis with regard to peritonitis in CAPD.

Adult↗
PubMed1992

High prevalence of Clostridium difficile diarrhoea during intensive chemotherapy for disseminated germ cell cancer.

A prospective, consecutive study of the aetiology of treatment-associated diarrhoea was conducted in 25 patients with disseminated germ cell cancer treated with intensive chemotherapy. Clostridium difficile was isolated in 45% of the diarrhoea episodes, which makes this species the most important bacterial pathogen in the development of clinically significant diarrhoea in this group of immunocompromised patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Neurally evoked responses of human isolated resistance arteries are mediated by both alpha 1- and alpha 2-adrenoceptors.

1. Human subcutaneous resistance arteries (internal diameter 113-626 microns) were mounted in an isometric myograph. Electrical field stimulation was applied either continuously in the form of a frequency-response curve or intermittently at 16 Hz. The magnitude of the maximum contraction induced by continuous stimulation expressed as a percentage of the response to a supramaximal concentration of noradrenaline (10 microM) was highly variable but unrelated to vessel calibre. Contractile responses to both continuous and intermittent stimulation were abolished by 1 microM tetrodotoxin. 2. Prazosin (100 nM and 1 microM, alpha 1-adrenoceptor antagonist) inhibited responses to continuous stimulation over a range of frequencies (2-8 Hz). The response to continuous stimulation at 8 Hz was inhibited by 78 +/- 6% by 1 microM prazosin. Rauwolscine (100 nM, alpha 2-adrenoceptor antagonist) had a smaller effect on contractions induced by continuous stimulation. Rauwolscine inhibited the response at 8 Hz by 36 +/- 6%. Rauwolscine at a higher concentration (1 microM) caused further inhibition of the response to continuous stimulation. Prazosin and rauwolscine in combination almost completely inhibited the response to continuous stimulation at concentrations of 1 microM. 3. Prazosin and rauwolscine inhibited responses to intermittent stimulation in a concentration-dependent manner. The IC50 for this action of prazosin was 3.7 +/- 1.6 nM and the maximum inhibition induced by 100 nM prazosin was 78 +/- 6%. The IC50 of rauwolscine was 12.0 +/- 1.3 nM and 100 nM rauwolscine caused a 86 +/- 7% reduction in the response to intermittent stimulation.Prazosin and rauwolscine in combination (each at 100 nM) caused marked inhibition of the response to intermittent stimulation leaving only 7.0 +/- 2.6% of the response.4. These data suggest that neurally released noradrenaline evokes contractions of human resistance arteries by activation of both alpha 1,- and alpha 2-adrenoceptors postjunctionally.

Arteries↗
PubMed1992

Initial cytoreduction by mitoxantrone and cytarabine has no impact on the outcome of interferon-alfa-2b therapy in chronic myelogenous leukemia.

Eleven previously untreated patients with chronic-phase Philadelphia-chromosome-positive chronic myelogenous leukemia were treated with cytotoxic chemotherapy followed by interferon-alfa-2b (IFN-alpha) maintenance. Initial chemotherapy consisted of three cycles of mitoxantrone 10 mg/m2 on day 1 and 2, and cytarabine 100 mg/m2 daily for 5 d. Complete hematological response was obtained in 9 (82%) patients with moderately associated toxicity. However, cytogenetic responses after three cycles were poor and transient (1 partial suppression and 2 minor suppression of Ph chromosome). Maintenance therapy with IFN-alpha was started in 10 patients at 5 x 10(6) U/m2 daily with dose reduction if hematologic toxicity or severe side-effects occurred. Of 9 evaluable patients treated for more than 3 months, 6 patients maintained a complete hematological response, whereas 1 patient remained in partial remission and 2 patients showed progressive disease. Cytogenetic evaluation showed partial suppression of Ph chromosome in 1 patient, whereas 1 patient had a minor response and 5 patients had no change or evolution of new chromosome abnormalities. As the results are not superior to IFN-alpha treatment alone, it is concluded that initial cytoreduction by mitoxantrone and cytarabine has no impact on the outcome of therapy in CML.

Adult↗
PubMed1992

Superoxide anion release from blood monocytes and alveolar macrophages in patients with diffuse lung fibrosis.

Superoxide anion release (O2-) after stimulation with phorbol myristate acetate was measured in alveolar macrophages (AM) obtained by bronchoalveolar lavage and in blood monocytes from 47 patients with diffuse interstitial lung disease: idiopathic pulmonary fibrosis (N = 15), hypersensitivity pneumonitis (N = 7), pneumoconiosis (N = 6) and sarcoidosis (N = 19). Differential cell counts demonstrated a lymphocyte predominance in patients with hypersensitivity pneumonitis (HP) and sarcoidosis while the other groups had neutrophil predominance. No correlation between O2- activity in alveolar macrophages (AM) or blood monocytes (BM) compared to lung function (VC and diffusing capacity) could be demonstrated. Smoking pneumoconiotics had significantly decreased BM O2- release (1.25 +/- 0.25 (SEM) nmol/min/10(6) cells) and significantly increased AM/BM O2- ratios (2.04 +/- 0.26) compared to smokers with idiopathic pulmonary fibrosis (IPF) who had the following mean values: BM O2- release = 2.58 +/- 0.25 and AM/BM O2- ratio = 0.86 +/- 0.23. When matched for sex and smoking, a significantly increased AM/BM O2- ratio was seen among patients with HP (2.19 +/- 0.98) in comparison with patients who had sarcoidosis (0.40 +/- 0.18). Patients with either HP or pneumoconiosis had generally elevated AM O2- release and reduced BM O2- release. These results suggest that environmentally related interstitial lung disorders (HP and pneumoconiosis) may be associated with elevated AM O2- release relative to BM O2- release in comparison to non-environmentally related disorders (IPF or sarcoidosis).

Adult↗
PubMed1992

Chemotactic activity of Helicobacter pylori sonicate for human polymorphonuclear leucocytes and monocytes.

The immunopathology of Helicobacter pylori associated active chronic gastritis, which is characterised by predominance of polymorphonuclear leucocyte infiltration, is largely unknown. To evaluate the role of bacterial components as inflammatory mediators ultracentrifuged sonicated preparations were made of clinical isolates of Helicobacter pylori. The crude sonicates were shown to exhibit chemotactic activity for human polymorphonuclear leucocytes and blood monocytes in a concentration dependent fashion. The potency was comparable with previously described bacterial derived cytotaxins. The cytotaxin(s) was non-dialysable and completely destroyed by proteinase. Heat treatment did not decrease the chemotactic activity, but in sonicate subjected to 100 degrees C for 15 minutes all activity disappeared after dialysis suggesting the breakdown of a larger protein to small fragments that are still biological active. By ammonium sulphate precipitation at increasing concentrations the cytotaxin(s) was selectively found in 10% ammonium sulphate saturation, and by further molecular gel separation the chemotactic activity was found in the molecular size range from 25 to 35 kDa. The demonstration of a polymorphonuclear leucocyte and monocyte cytotaxin from Helicobacter pylori sonicate may help in understanding the mucosal immune response in gastric inflammatory diseases.

Bacterial Proteins↗
PubMed1992

Age-dependent changes in alpha-adrenoceptor-mediated contractility of isolated human resistance arteries.

Human subcutaneous resistance arteries (122-298 microns), isolated from 139 patients undergoing surgery, were mounted in an isometric myograph. With the use of multiple regression analysis, five different modes of activation were examined for possible associations with age and mean arterial blood pressure of the patients: the contractile responses to 10 microM norepinephrine (mixed alpha 1-agonist/alpha 2-agonist), perivascular nerve stimulation, 10 microM phenylephrine (alpha 1-agonist), 100 microM B-HT 933 (alpha 2-agonist), and depolarization by potassium chloride. Blood pressure increased significantly with age. Blood pressure independently was not correlated to any mode of activation. With increasing patient age, however, responses to norepinephrine, phenylephrine, and perivascular nerve stimulation decreased, whereas the response to B-HT 933 increased; responses to potassium chloride were unaltered. Also corrected for changes in blood pressure, age independently was negatively correlated to the response to norepinephrine and phenylephrine, whereas a positive, though nonsignificant (P value = 0.12), correlation was observed between age independently and the response to B-HT 933. These data suggest that the ability of isolated human resistance arteries to evoke contractions medicated by postjunctional alpha 1-, but not alpha 2-adrenoceptors, decreases with age.

Adrenergic alpha-Agonists↗
PubMed1992

Bioavailability and analgesic effect of sustained release cetobemidone capsules in cancer patients with chronic pain of malignant origin.

Ever since its introduction in 1952, Ketogan has consisted of a combination of the opioid cetobemidone and a spasmolytic drug, A29, in the ratio of 1:5. Its main limitations are the relatively short duration of action and an apparent ceiling effect due to A29. We therefore developed a cetobemidone formulation with sustained release properties (cetobem. s.r.). Forty-seven patients with advanced cancer with moderate/severe pain, treated with regular doses of Ketogan tablets took part in an open phase 1 type pharmacologic/toxicologic study comparing Ketogan tablets and cetobem. s.r. The patients spent at least 4 days in the department. After evaluation during 12 h with Ketogan tablets (3-4 dosing intervals), a loading phase lasting for 36 h with cetobem. s.r. given twice/24 h (total dose of Ketogan tablets per 24 h divided by 2), and synchronous reduction of the dose of Ketogan tablets, a similar evaluation period of 12 h was performed when on treatment with cetobem. s.r. alone. Comparison of data from the two observation periods showed the following: Average relative bioavailability 0.77 SD 0.28. Only 2 patients were remedicated before 12 h when on cetobem. s.r. Duration of action mean 11.9 h, SD 0.3 h. There was no significant difference between Ketogan tablets and cetobem. s.r. periods concerning 'time with no pain'. Side-effects were few. The only significant difference was dry mouth being more severe during the tablet period. Vital signs were unaffected by treatment. It is concluded that cetobem. s.r. can be given every 12 h to cancer patients with chronic pain with satisfactory analgesic effect, a very modest change in side-effect profile and no significant effects on vital signs when substituting cetobem. s.r. for Ketogan tablets in equal daily doses.

Adult↗