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PubMed2000

[Factors modifying frequency of publications of clinical research results exemplified by medical dissertations].

BACKGROUND AND OBJECTIVE: The problem of so-called "publication bias"--distortion of statements about an event by selective publication--is receiving growing attention. Assessment of the results of a given study can be affected by knowing the factors that favour or inhibit the publication of its results. METHODS: The data were based on an analysis of 371 medical doctoral dissertations on clinical research. Characteristic features of the dissertations were obtained by questionnaire, supplemented by MEDLINE search and, additionally, by personal enquiry about the publications. Bivariate and multivariate analysis of the characteristic features was used to evaluate the factors that influenced publication of a dissertation. RESULTS: There were mainly three factors that influenced the decision whether or not a dissertation was published: (1) a positive result of the study (odds ratio 2.5, 95% confidence interval 1.12-5.75); (2) the publishing activity of the dissertation's referee (odds ratio 3.8, 95% confidence interval 1.77-7.97; and (3) the quality of the statistical analysis of the dissertation's data (odds ratio 1.67, 95% confidence interval 0.99-2.80). CONCLUSION: A distinct publication bias can be demonstrated also in the case of doctoral dissertations in that positive results are clearly published more often than negative ones.

Academic Dissertations as Topic↗
PubMedDate not supplied

[Assisted ventilation of newborn infants during sleep. Study of factors modifying adaptation to ventilation].

During sleep, of ventilated newborns and young infants, spontaneous respiratory movements may occur, unrelated to the ventilation impulsions. The respiratory pattern is then classified as "active". On the contrary, the respiratory pattern is classified as "passive", when all respiratory movements are related to the ventilation insufflation. The factors which influence the dependence on the ventilator are studied in a group of 20 newborn and young infants. Prematurity, some biological data such as hyperoxia, hypocapnia, seem to favor this dependence. A rapid rate of ventilation (superior to 30/minute) is rarely related to an active respiration; a slow rate of ventilation seems favor this respiratory pattern. It is clear that adaptation to artificial ventilation is better during quiet sleep than during active sleep. Some physiopathological considerations are developed.

Adaptation, Physiological↗
PubMed1975

Serum factors modifying cell mediated immunity to rat hepatoma d23 correlated with tumour growth.

Sera from rats bearing a progressively growing transplanted aminoazo-dye-induced hepatoma (hepatoma D23) have been examined for the presence of hepatoma D23-specfic antigen, antibody and immune complexes throughout the course of tumour growth. The levels of these factors have been correlated with the in vitro blocking and inhibition of cytotoxic lymph-node cells from immunized animals for cultured tumour cells. Sera from animals bearing small tumours (7-14 days after tumour implantation contain free tumour-specific antigen whilst immune complexes could not be detected. Although these sera were neither blocking nor inhibitory under the normal conditions of the test, when concentrated two and fourfold, inhibition but not blocking of lymph-node cell cytotoxicity could be detected. In comparison sera from animals bearing large tumours (24-28 days) blocked but did no inhibit in vitro lymph-node cell cytotoxicity and this correlates with the presence of tumour-specific immune complexes in antibody excess. Animals with intermediate-sized tumours had high levels of both blocking and inbibitory activity in the serum, these effects becoming apparent when neither free antibody nor free antigen could be detected. The relevance of these findings to the mechanism by which a growing tumour may escape specific cellular immune destruction is discussed.

Animals↗
PubMed1998

[Value of phase-contrast microscopy in the etiological diagnosis of hematuria in adults. Part II: Analysis of factors modifying morphology of erythrocytes in urine sediment].

In 41 patients with glomerular hematuria diagnosed by renal biopsy no correlation between intensity of tubulo-interstitial changes and range of dysmorphic erythrocytes (E) in phase-contrast microscopy (PCM) was found. However, such correlation existed in the case when acanthocytes in PCM were detected. From factors of potential influence on the morphology of E such as value of proteinuria, glomerular filtration rate, crystalluria, osmolarity and pH of urine, none had any significant role in changing the morphology of E of glomerular as well as of non-glomerular origin.

Adult↗
PubMedDate not supplied

[What factors modify the condition of the newborn infant in emergency cesarean section?].

Based on 207 emergency caesarean sections carries out in 66 maternity units in North Rhine Westphalia, the condition of the newborns (pH, UA and Apgar-index after 1 minute) was examined focusing the dependence of these variables from the time management (5 time factors were analysed). Rank-correlation coefficients according to SPEARMAN were calculated and a stepwise multiple regression analysis was performed. We found a significant (P less than 0.005) positive correlation on the one hand between the preparation time for the caesarean-section (time 1) and the actual pH (UA) and on the other hand between the total time (decision to perform a caesarean section up to the delivery of the baby (time 3)) and the actual pH, UA. No significant correlation was found between the time-factors and the Apgar-index (1 min). As the correlations are positive, this means that very low pH values are associated with short time intervals and high pH values with longer time intervals respectively. We concluded, that in case of an emergency caesarean section the urgency of the emergency itself controls and determines the time management. The spatial situation in each hospital which is reflected in the time factors 4 and 5 seems to be of less important for the overall result.

Acid-Base Equilibrium↗
PubMed1998

Factors modifying the effect of hyperglycemia on the development of retinopathy in adolescents with diabetes. Results of the Berlin Retinopathy Study.

The Berlin Retinopathy Study follows children from the onset of diabetes with serial retinal examinations by fluorescein angiography. It confirmed that long-term poor glycemic control, both before and after puberty, is the major risk factor for the development of retinal changes. The relationship between long-term HbAlc and background retinopathy follows an exponential, non-linear function. Apart from glycemia, several other factors (age at onset, puberty, lipids, blood pressure, genetic factors, smoking) may be of varying relevance in the individual patient. Nevertheless, best glycemic control from the onset of diabetes appears to be of outstanding importance as the HbAlc levels already during the first year of diabetes are related to the later development of background retinopathy.

Adolescent↗
PubMed1998

Osmotic effects as a factor modifying insecticide toxicity on Aedes and Artemia.

Euryhaline species are more tolerant of various insecticides under isosmotic conditions. Two euryhaline species, Aedes taeniorhynchus (Wiedemann) and Artemia sp., were exposed to four insecticides (aldicarb, dimethoate, imidacloprid, tebufenozide), under isosmotic and hyperosmotic conditions. Mortality under these two osmotic conditions was observed and compared to evaluate salinity as a contributing factor to insecticide toxicity. Artemia was more tolerant of all chemicals tested than A. taeniorhynchus under isosmotic conditions based on the percentage mortality observed. Mortality of Artemia under isosmotic conditions was dependent on the length of exposure; A. taeniorhynchus did not exhibit time dependence. Less mortality was observed in populations of both test species under isosmotic conditions compared with hyperosmotic conditions. However, the variation in mortality due to exposure to test chemicals was of greater magnitude in A. taeniorhynchus than Artemia. This result indicates that higher salinity is a greater stress on A. taeniorhynchus than Artemia when exposed to the test insecticides at the concentration ranges tested in this study.

Aedes↗
PubMed1976

Effect of different factors modifying the activity of some enzyme systems of the endoplastic reticulum on the sensitivity of cell organelles against the damaging action of chemical agents. I: Interrelations between the activity of some enzyme systems located in endoplasmic reticulum and hepatotoxicity of carbon tetrachloride.

An increased stability of liver lysosomes and mitochondria of burned, dehydrated and tumour-bearing rats has been found in the present investigations. Using biochemical criteria we were able to show that the membranes of liver subcellular particles of these animals become more resistent to the labilizing action of CCl4. The latter effect was confirmed by electron microscopic data. The tumour growth, dehydration and burning of rats as well as sleep deprivation, overheating, lanthanum and ruthenium red have been shown to cause changes in the activity of some enzyme-systems located in endoplasmic reticulum. The protective action of these chemical, pathological and stress factors against CCl4 produced damage to the cell organelles studied is discussed in relation to the activity of the drug metabolizing pathways; biochemical (modifying of some enzyme activity) as well as pharmacological (duration of hexobarbital sleep) data were used as criteria for the activity of these pathways.

Acid Phosphatase↗
PubMed1997

Nutritional factors modify the inhibition of CNS development by combined exposure to methadone and ethanol in neonatal rats.

The consequences resulting from the combined exposure to methadone and ethanol during a time period equivalent to the third trimester brain growth spurt was the purpose of this study. Rat pups were treated on postnatal days 6-10 and sacrificed on postnatal day 11. Body weight along with the heart, liver, kidneys, whole brain, cerebrum, cerebellum, and brain stem weights were measured. The impact of nutritional factors were identified by delivery of the drug solutions in one of two intubation vehicles differing in both caloric density and composition. Ethanol and methadone in combination result in significantly increased detrimental effects compared to methadone alone only when possible nutritional compromise was present. The combined effect of both drugs significantly inhibited body growth and the development of all brain regions studied. Neither drug alone, nor in combination, produced significant inhibition of growth in the liver, heart, or kidney. The nutritional status of the pup, as represented by vehicle composition, was able to modify the specific drug effects and suggests that nutritional status can mask or enhance the determination of specific drug effects.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Increased transduction of skeletal muscle cells by fibroblast growth factor-modified adenoviral vectors.

Gene therapy for Duchenne muscular dystrophy will likely require that the corrective dystrophin gene be delivered to a high fraction of muscle fibers in vivo. Because of the large size of the dystrophin cDNA, adenoviral (Ad) vectors have been developed for this application. However, Ad vectors transduce mature muscle inefficiently in part due to downregulation of Ad receptors on these cells. To circumvent this problem, we have tested fibroblast growth factor-2 (FGF) and insulin-like growth factor (IGF) as ligands for their ability to enhance Ad transduction of muscle cells. In this work, we demonstrate that covalent conjugation of FGF, but not IGF, to Ad5 vectors mediates substantial increases in transduction of skeletal muscle cells in vitro and dystrophic in vivo. Ad5 vectors expressing reporter genes were cross-linked to the ligands, using bifunctional polyethylene glycol (PEG) molecules. Ad-PEG-FGF mediated 1000- and 200-fold increases in transduction on C2C12 myoblasts and myotubes in vitro when compared with Ad5, Ad-PEG, or Ad-PEG-IGF. When tested in vivo in mdx mice, Ad-PEG-FGF mediated 6-fold higher transduction in skeletal muscle than unmodified Ad5. Similar results were seen when using lacZ as a reporter gene to observe transduction qualitatively. These data suggest that FGF may be a useful cell-binding ligand to enhance gene delivery by Ad and other vectors into skeletal muscle for the gene therapy of Duchenne muscular dystrophy and other muscle-related diseases.

Adenoviridae↗
PubMed1984

[Effect of a modifying factor on the sensitivity of Crithidia oncopelti to levorin].

The paper deals with possible discovery of ways for increasing sensitivity of trypanosomides to polyenic antibiotics. The following substances were tested: sodium pyruvate and acetate, calcium salts, ascorbic acid and 1-valine. The total number of the cells and the number of the viable cells in the culture and their morphological characteristics were used as the criteria for estimation of the C. oncopelti sensitivity. It was shown that sodium acetate most actively modified the levorin effect on C. oncopelti. Its addition in a concentration of 40 mg/ml to the cultivation medium with levorin in a concentration of 1 microgram/ml induced a trypanocidal effect. With the use of levorin alone such an effect was observed when the antibiotic was used in a concentration of 10 micrograms/ml. The growth rate of the protozoon was decreased by 60-80 per cent as compared to the control. The number of the viable cells was lowered 4 times. The morphology of the culture markedly changed. This indicates that the presence of sodium acetate as a modifier in the culture medium allowed one to decrease 10 times the dose of levorin and to preserve the trypanocidal effect.

Acetates↗