Showing papers by "University of Bergen published in 1989"

High abundance of viruses found in aquatic environments.

Abstract: The concentration of bacteriophages in natural unpolluted waters is in general believed to be low, and they have therefore been considered ecologically unimportant. Using a new method for quantitative enumeration, we have found up to 2.5 x 10(8) virus particles per millilitre in natural waters. These concentrations indicate that virus infection may be an important factor in the ecological control of planktonic micro-organisms, and that viruses might mediate genetic exchange among bacteria in natural aquatic environments.

Condensation and Cloud Parameterization Studies with a Mesoscale Numerical Weather Prediction Model

Abstract: This paper presents the implementation of a parameterization scheme for convective and stratiform condensation (with cloud water as a prognostic variable) into a fine mesh numerical weather prediction model. The results from a 36 h integration of the model, with grid distance 50 km, indicate that the new condensation scheme contributes to an improved forecast compared to that obtained by the original model. Furthermore, from a qualitative comparison with satellite pictures, it is found that the prediction of condensation-cloud parameters is quite realistic.

Classification and distribution ofFicus

Abstract: The classification of the genusFicus has changed considerably in the course of time and is still the subject of further research and discussion. The main subdivisions in the most recent classification by Corner12 are presented together with the genera of pollinating fig wasps (Agaonidae) associated with them. These subdivisions are discussed and grouped according to morphological and functional traits, in particular in connection with the unique pollination system. Two main groups are recognized: one with only monoecious species and the other with predominantly (gyno)dioecious species. The former comprises two subgroups (Pharmacosycea andUrostigma) and the latter three, more profoundly different subgroups (Ficus, Sycidium andSycomorus). The neotropical representatives of the genus are discussed in somewhat more detail. In addition, the distribution of the genus is summarized for the three main regions of distribution; Africa, America, and Asia-Australasia. Finally the concordance between subdivisions ofFicus and those of the Agaonidae is briefly discussed.

New malignancy grading is a better prognostic indicator than Broders' grading in oral squamous cell carcinomas.

Abstract: The prognostic value of histopathologic grading of oral squamous cell carcinomas (SCC) has varied from not any to highly significant. We have retrospectively studied all (130) SCCs registered in Norway 1963-72 in the buccal and maxillary alveolar mucosa. From 68 of these cases biopsy specimens of acceptable quality were obtained. Broders' method of grading was compared with a modification of a recent malignancy grading system recommended by Anneroth et al. which was performed only within the histologically most invasive areas of the tumors. Cox's multivariate survival analyses showed that this grading in the invasive sites had highly significant prognostic value. Broders grade had no prognostic value. The stage of tumor had also prognostic value. These highly significant results indicate that the histologically invasive areas may be primarily responsible for the clinical behavior of the tumor, and this may be of importance for the choice of therapy for oral SCC.

Estimation of earthquake hazard parameters from incomplete data files. Part I. Utilization of extreme and complete catalogs with different threshold magnitudes

Abstract: The maximum likelihood estimation of earthquake hazard parameters (maximum regional magnitude, m max , earthquake activity rate λ, and b parameter in the Gutenberg-Richter equation) is extended to the case of mixed data containing large historical events and recent complete observations. The method accepts variable quality of complete data in different parts of a catalog with different threshold magnitude values. As an illustration, the procedure is applied for the estimation of seismicity parameters in the area of Calabria and eastern Sicily.

Distribution of 4-Hydroxy-N-desmethyltamoxifen and Other Tamoxifen Metabolites in Human Biological Fluids during Tamoxifen Treatment

Abstract: Several metabolites of tamoxifen, including 4-hydroxy-N-desmethyltamoxifen (metabolite BX), 4-hydroxytamoxifen (metabolite B), N-desmethyltamoxifen (metabolite X), the primary alcohol (metabolite Y), and N-desdimethyltamoxifen (metabolite Z) were identified and their concentrations determined in fluids and feces from patients receiving chronic tamoxifen treatment. The biological samples investigated were serum, pleural, pericardial and peritoneal effusions, cerebrospinal fluid, saliva, bile, feces, and urine. In serum, tamoxifen itself, and the metabolites X and Z were the prevailing species, but significant amounts of the metabolites Y, B, and BX were also detected. About 3 h after drug intake tamoxifen as well as Y, B, BX, X, and Z showed a peak in serum. This may be explained by efficient metabolism of the metabolite precursor before being distributed to peripheral compartments. Upon drug withdrawal all metabolites showed first-order elimination curves which paralleled that of tamoxifen suggesting that their rate of elimination exceeded that of tamoxifen and that the serum levels are production rate limited. The protein binding of tamoxifen and its major serum metabolites (Y, X, Z) was determined and found to be higher than 98%. Albumin was the predominant carrier for tamoxifen in human plasma. The concentrations of tamoxifen and its metabolites in pleural, pericardial, and peritoneal effusions equalled those detected in serum, corresponding to an effusion/serum ratio between 0.2 and 1. Only trace amounts of tamoxifen and metabolite X were detected in cerebrospinal fluid (CSF/serum ratio less than 0.02). In saliva, concentrations of tamoxifen and X exceeded the amounts of free drug in serum, suggesting active transport or trapping of these compounds in the salivary gland. Bile and urine were rich in the hydroxylated, conjugated metabolites (Y, B, and BX), whereas in feces unconjugated metabolite B and tamoxifen were the predominating species.

Fully automated fluorescence assay for determining total homocysteine in plasma.

Abstract: Homocysteine exists in human plasma as various (mixed) disulfides. Most plasma homocysteine (about 70%) is protein bound, probably via a disulfide bond to albumin, whereas homocysteine-cysteine mixed disulfide is the predominating form in the free fraction. We here present a method for the determination of total homocysteine, which includes both fractions. Plasma was initially treated with sodium borohydride to reduce the disulfide bonds, and the liberated thiols were derivatized with monobromobimane. The derivatized sample, still containing the plasma proteins, was injected onto a strong cation-exchange column, from which the homocysteine derivative was directed by column switching into a cyclohexyl silica (CH) column. The homocysteine derivative was top-concentrated on the CH column, then rapidly eluted with a steep gradient of methanol. Both the derivatization procedure and chromatography were performed with a combined sample processor and sample injector from Gilson (Model 232-401). Within-run and between-run precision (CV) was less than 4%, and the detection limit of 0.2 pmol was sufficiently low for monitoring homocysteine in plasma. We verified the assay against two established manual methods for the determination of total homocysteine in plasma. This, the first fully automated assay for total plasma homocysteine, allows the unattended analysis of 70 samples per 24 h.

Molecular cloning of human uracil-DNA glycosylase, a highly conserved DNA repair enzyme.

Abstract: Uracil-DNA glycosylase is the DNA repair enzyme responsible for the removal of uracil from DNA, and it is present in all organisms investigated. Here we report on the cloning and sequencing of a cDNA encoding the human uracil-DNA glycosylase. The sequences of uracil-DNA glycosylases from yeast, Escherichia coli, herpes simplex virus type 1 and 2, and homologous genes from varicella-zoster and Epstein-Barr viruses are known. It is shown in this report that the predicted amino acid sequence of the human uracil-DNA glycosylase shows a striking similarity to the other uracil-DNA glycosylases, ranging from 40.3 to 55.7% identical residues. The proteins of human and bacterial origin were unexpectedly found to be most closely related, 73.3% similarity when conservative amino acid substitutions were included. The similarity between the different uracil-DNA glycosylase genes is confined to several discrete boxes. These findings strongly indicate that uracil-DNA glycosylases from phylogenetically distant species are highly conserved.

Comparison of clinical and postmortem diagnosis of pulmonary embolism.

Abstract: The incidence of pulmonary embolism and the number of clinically missed diagnoses of it in necropsies carried out between 1960 and 1984 at this department were investigated. Pulmonary embolism primarily affects elderly people with serious underlying disease; in this study it was found more often in women. The incidence of pulmonary embolism (9% of all necropsies) was unchanged during the period studied. In contrast, pulmonary embolism as the "sole" cause of death increased (p less than 0.0005). Although most pulmonary emboli were the immediate cause of death, the clinical diagnosis was often missed (in 84% of all cases). Furthermore, such clinically missed diagnoses increased over the years (p less than 0.005), especially in patients with heart disease and cancer. Without necropsy there will be considerable underdiagnosis of pulmonary embolism, therefore providing a misleading figure in the death statistics for this often fatal disease.

Prevalence and Incidence in the Study of Antisocial Behavior: Definitions and Measurements

Abstract: In epidemiology, the concepts of prevalence and incidence are central (Bradford Hill, 1977; Last, 1983; Morris, 1975). Basically, prevalence (or prevalence rate) refers to the number of diseases or spells of disease existing at a particular point in time or within a specified time period related to the total number of persons exposed to risk (a population or a defined group of people). Incidence (or incidence rate) on the other hand measures the rate of appearance of new cases in the group or population, i.e., the number of diseases/spells of disease beginning within a specified period of time related to the total number of persons exposed to risk during that period.1

Improved measurement of androgen receptors in human breast cancer.

Abstract: Molybdate-stabilized androgen receptors have been quantitated in cytosols derived from 1026 malignant breast tumors including all new cases of primary breast cancer reported in the western region of Norway during the 3-year period 1985-1987. A simple single point saturation assay using the synthetic labeled ligand methyltrienolone was evaluated for this purpose. This approach also allowed the simultaneous determination of estrogen and progesterone receptor from the same cytosol preparation. The cytosol content of albumin was also recorded in order to control for dilution by extracellular proteins. Androgen receptor was the sex hormone receptor most frequently found both in primary and secondary breast cancer. In primary tumors 84.9% (723 of 852) showed a cytosol concentration higher than 10 fmol/mg protein compared to 71.2 and 67.1% for estrogen and progesterone receptors, respectively. This incidence is about 2 times higher than previously reported for androgen receptors in the literature and may be due to the stabilizing effects of molybdate and a serine protease inhibitor on the recovery of active binding sites in cytosol. Cytosol concentration of androgen receptor is generally lower than that of the other sex hormone receptors; the average level was 65.5 fmol/mg cytosol protein compared to 86.8 and 84.7 for estrogen and progesterone receptors, respectively. Both incidence and cytosol concentrations were lower for all sex hormone receptors in soft tissue metastasis than in the primary tumor. This decrease is not likely to be due to differences in tumor cellularity since metastatic tumors appear to be more cellular as judged from a lower cytosol content of extracellular proteins (albumin). No significant differences were observed in any parameter investigated between different metastatic sites (skin, lymph nodes). Androgen receptor levels were strongly correlated to estrogen and progesterone receptor concentration in both primary and secondary cancers. Cytosol androgen receptor concentration increases with age. This increase is more significant in metastatic than in primary tumors. Evidently, tumor cellularity is a confounding factor in primary tumors since tumor cytosols from younger patients showed a higher content of extracellular proteins. Receptor levels in lymph node metastasis did not exhibit age dependence. This may suggest that locally produced factors rather than circulating levels of sex steroids modulate tumor receptor expression. In metastatic tissues androgen receptors are present with twice the frequency of progesterone receptors and one in four of these tumors express androgen receptor as their sole sex hormone receptor. This supports the view that some of the beneficial effects of high dose progestin treatment of advanced breast cancer are mediated through the androgen receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparison of the two classes of binding sites (A and B) of type I and type II cyclic-AMP-dependent protein kinases by using cyclic nucleotide analogs.

Abstract: cAMP analogs, all 96 of which were modified in the adenine moiety, were examined quantitatively for their ability to inhibit the binding of [3H]cAMP to each of the two classes (A and B) of cAMP-binding sites of type I (rabbit skeletal muscle) and type II (bovine heart) cAMP-dependent protein kinase. The study showed that analogs can be constructed that have a higher affinity than cAMP for a binding site. N6-phenyl-cAMP had 18-fold increased affinity for site A of RI (AI) and 40-fold increased affinity for site AII. 2-chloro-8-methylamino-cAMP had a 7-fold increased affinity for BI, and 8-(4-chlorophenylthio)-cAMP had 17-fold increased affinity for BII. Analogs could discriminate between the two classes of binding sites by more than two orders of magnitude in binding affinity: 2-chloro-8-methylamino-cAMP had 170-fold higher affinity for BI than for AI, and 2-n-butyl-8-thiobenzyl-cAMP had 700-fold higher affinity for BII than for AII. Analogs could also discriminate between the homologous binding sites of the isozymes: 2-n-butyl-8-bromo-cAMP had 260-fold higher affinity for AI than for AII (22-fold higher for BII than BI), and 8-piperidino-cAMP had 50-fold higher affinity for BII than for BI (and 50-fold higher for AI than for AII). The data suggest the following conclusions. (a) Stacking interactions are important for the binding of cAMP to all the binding sites. (b) Subtle differences exist between the sites as to the optimal electron distribution in the adenine ring since modifications that withdraw electrons at C2 and donate at C8 favour binding to BI, and disfavour binding to AI and AII. (c) There are no hydrogen bonds between the adenine ring of cAMP and any of the binding sites. (d) All sites bind cAMP in the syn conformation. (e) The subsites adjacent to the N6 and C8 positions may have nonpolar neighbouring regions since hydrophobic substituents at N6 could increase the affinity for AI and AII and similar substituents at C8 could increase the affinity for BII. Finally, (f) the sites differed in their ability to accomodate bulky substituents at C2 and C8. For all compounds tested, their potency as activators of protein kinases I and II was found to correlate, in a predictable fashion, to their mean affinity for the two classes of binding sites, rather than to the affinity for only one of the sites.

Fasting plasma homocysteine as a sensitive parameter of antifolate effect: a study of psoriasis patients receiving low-dose methotrexate treatment.

Abstract: We have investigated the effect of low-dose methotrexate (25 mg weekly) on plasma homocysteine in 13 patients who had psoriasis. Total, free, and protein-bound homocysteine were determined both during fasting and after methionine loading. Psoriasis patients had significantly higher basal plasma homocysteine levels than age-matched control subjects. In addition, the methionine loading test was abnormal in four of the patients, but this was not significant. Psoriasis patients, although not folate deficient, did have lower serum folate levels than control subjects. There was a significant and transient increase in fasting plasma homocysteine levels within 48 hours after administration of low-dose methotrexate. This response was repeated after each administration and was observed eight to 20 times in three patients whose progress was monitored for 2 to 6 months. Notably, methotrexate did not affect the plasma profile for homocysteine after methionine loading. This study showed the level of fasting plasma homocysteine to be a sensitive and responsive parameter of antifolate drug treatment.

Associated disorders in myasthenia gravis: autoimmune diseases and their relation to thymectomy.

Abstract: The prevalence of myasthenia gravis (MG) in the counties of Hordaland and Sogn & Fjordane on January 1, 1984 was 9.6 per 100,000 inhabitants. Other autoimmune diseases were found in 11 out of 48 MG patients. The occurrence of autoimmune thyroiditis (5 patients, 10.4%) and systemic lupus erythematosus (4 patients, 8.3%) in the MG patients was clearly higher than that reported in the general population. Rheumatoid arthritis was found in 2 patients (4.2%). The autoimmune diseases were mainly recorded among the nonthymectomized MG patients. In addition to those with definite diseases of autoimmune nature, 3 other MG patients had thyroid antibodies and 1 had antinuclear factor without clinical evidence of autoimmune disease. Seven MG patients (14.6%) had unspecific arthralgia during active periods of MG. Two MG patients had ankylosing spondylitis.

A clinical and roentgenological study of 55 cases of root perforation

Abstract: The treatment outcome of 55 root perforations in man were related to pretreatment conditions and various treatment procedures used, with a mean recall period of 3 years 5 months. In this study maxillary teeth were perforated three times more often (74.5 per cent) than mandibular teeth (25.5 per cent); 47 per cent of the perforations were due to endodontic and 53 per cent due to prosthodontic treatment. The buccal and mesial root surfaces as well as the midroot areas were most often perforated. In 25 per cent, radiographic changes were directly related to the perforated areas. Twenty-eight perforations were repaired by orthograde fillings with gutta-percha and Kloro-percha N-phi; eight received a combined orthograde and surgical repair, and in only three cases a surgical approach was used. Four cases received no treatment but were recalled, and twelve perforations showed a size and location hopeless for repair; the teeth were therefore extracted. Five failures of the primary orthograde treatment group later underwent surgical treatment and were followed up for 3 years 3 months. The overall success rate in the primary treatment group of teeth was 56 per cent while 36 per cent became failures. Five failures were retreated, and four of these became successful. A combined orthograde and surgical repair of the perforations provided the most favourable outcome with 92 per cent successful. The study stresses the importance of preventing this type of treatment complication.

Increasing incidence of diabetes mellitus in Norwegian children 0-14 years of age 1973-1982.

Abstract: A retrospective technique was used to register all newly diagnosed cases of diabetes mellitus in Norwegian children 0–14 years of age during the ten-year period 1973–1982. A total of 1,914 newly diagnosed cases were detected, from an average population of 932,037 children. The degree of ascertainment was near to 99%. The male incidence exceeded the female incidence by 12% (p<0.02). The mean yearly incidence for the ten-year period was 20.5 per 100,000. Comparing the two five-year periods 1973–1977 and 1978–1982, the mean yearly incidence increased from 18.5 to 22.7 per 100,000 (p<0.0001). There was a marked geographic variation with the highest incidence in the south-east and lower incidence in the northern part of the country. However, in the northern part of the country, there was a remarkable increase of the annual incidence from the first to the second five-year period (12.9 vs 19.3 per 100,000). The highest numbers of new cases were detected in the months of January and October, and the lowest numbers in May and July. The seasonal pattern was significantly different from a uniform distribution of new cases throughout the year (p<0.001). The age-specific incidence increased towards a peak at 12 years for both sexes. In conclusion, Norway has a high and apparently increasing incidence of childhood diabetes. The geographic variation and secular trend present challenging clues for a search of etio-pathogenic factors.

Phytoplankton blooms in the vicinity of Palmer Station, Antarctica

Abstract: Fifteen oceanographic stations were occupied in the vicinity of Anvers Island, Antarctica, in January of 1985 and 1987. All stations showed high phytoplankton biomass (4.0 to 30 μg chl-a/liter) which was either uniformly distributed in the upper mixed layer or showed a pronounced sub-surface maximum at 4–5 m depth. As phosphate was less than 0.02 μm and nitrate about 2.0 μm in surface waters, it appears that nutrient limitation of phytoplankton growth may be of importance during such blooms. This view is supported by chemical measurements of the particulate material which showed high chl-a/ATP ratios (about 7.7), as well as high POC/ATP ratios (about 700). Microscopical analysis revealed a dominance of large-celled diatoms and the near absence of heterotrophic protozoans. Size fractionation studies showed that the nanoplankton accounted for only 28% of the total phytoplankton biomass. When phytoplankton biomass reaches the levels found at these stations, it appears that the cells are light-limited and hence dark-adapted, which results in the high chl-a/ATP ratios and the low assimilation values (0.49–1.64) obtained in our studies. Under such conditions greater than 50% of the total phytoplankton biomass is found below the 1% light level.

Enteroaggregative Escherichia coli and Salmonella associated with nondysenteric persistent diarrhea

Abstract: A hospital-based case-control study including 92 children with diarrhea for longer than 14 days and 92 controls without gastrointestinal symptoms was performed to describe the association between the excretion of enteric pathogens and persistent diarrhea. In patients the most frequently isolated stool pathogens were enteroaggregative Escherichia coli (19.6%), nontyphoidal Salmonella spp. (17.4%), E. coli with diffuse adherence pattern (7.6%), G. lamblia (7.6%) and enterotoxigenic E. coli (5.4%). The excretion rates in patients were significantly greater than in controls only for nontyphoidal Salmonella spp. (P = 0.0006) and enteroaggregative E. coli (P = 0.016).

Traumatic ulcers and pain in adults during orthodontic treatment.

Abstract: In the present investigation the frequency of oral ulcers and pain in 79 adults orthodontic patients was recorded. Only four of all patients had never had oral ulceration during treatment, but 83% of the patients characterized the trouble as minor. About 47% of the patients said that ulcers caused by the fixed appliance were the most annoying part of the treatment, and 38% said that activation of the appliance caused the most discomfort. In about 63% of the patients there was less pain when the treatment had lasted for some months, and in 24% there was no significant change in the discomfort. The pain following activation lasted for only 2-3 days (71%), but 20% had pain for more than 3 days, and five individuals felt pain constantly. The recurrence of aphthous ulceration (RAU) was not significantly affected during the orthodontic treatment, and in only one case was there an increase in the occurrence of herpes labialis.

Neoplasms of the central nervous system in Norway

Abstract: The Norwegian Cancer registry includes reports on 8,933 cases of primary central nervous system neoplasms diagnosed in the period 1955-1984. Before submitting this data set to epidemiological analysis, errors were searched out and subsequently corrected, and a quality control was performed. First, seven categories of neoplasm records likely to be faulty were defined. In this way 109 cases (1.2% of the total) were identified for extensive study. Minor or major errors were found and corrected in 86 cases. The main source of error was misinterpretation of data by cancer registry staff (67 out of 109 cases). The second approach was to evaluate the quality of the corrected data set by a random draw of 300 cases. Errors concerning total incidence rates and rates for main groups of gliomas, meningiomas and neurilemmomas represented 0.3% of the total, and altogether 9.3% of errors of varying severity were revealed. The series is discussed with regard to prerequisites for serving as reliable data on CNS neoplasm epidemiology. The results indicate that the data from the Norwegian Cancer Registry is sufficiently valid for a thorough study of CNS neoplasms.