1,720,964 research outputs found
Alterations of alveolar type II cells and intraalveolar surfactant after bronchoalveolar lavage and perfluorocarbon ventilation. An electron microscopical and stereological study in the rat lung
Full text linkAbstract Background Repeated bronchoalveolar lavage (BAL) has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC) can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool. Methods Male wistar rats were surfactant depleted by BAL and treated for 1 hour by conventional mechanical ventilation (Lavaged-Gas, n = 5) or partial liquid ventilation with PF 5080 (Lavaged-PF5080, n = 5). For control, 10 healthy animals with gas (Healthy-Gas, n = 5) or PF5080 filled lungs (Healthy-PF5080, n = 5) were studied. A design-based stereological approach was used for quantification of lung parenchyma and the intracellular and intraalveolar surfactant pool at the light and electron microscopic level. Results Compared to Healthy-lungs, Lavaged-animals had more type II cells with lamellar bodies in the process of secretion and freshly secreted lamellar body-like surfactant forms in the alveoli. The fraction of alveolar epithelial surface area covered with surfactant and total intraalveolar surfactant content were significantly smaller in Lavaged-animals. Compared with Gas-filled lungs, both PF5080-groups had a significantly higher total lung volume, but no other differences. Conclusion After BAL-induced alveolar surfactant depletion the amount of intracellularly stored surfactant is about half as high as in healthy animals. In lavaged animals short time liquid ventilation with PF5080 did not alter intra- or extracellular surfactant content or subtype composition.</p
Effects of perfluorocarbons and perfluorocarbons/surfactant emulsions on growth and viability of group B streptococci and Escherichia coli
No full textObjective. Partial liquid ventilation with perfluorocarbons (PFG) might be used as a new ventilatory strategy to treat respiratory insufficiency in congenital pneumonia. The present study investigates for the first time effects of PFC on growth and viability of group B streptococci (GBS) and Escherichia coli, bacteria frequently causing congenital pneumonia. Design: Prospective, in vitro study. Setting: Research laboratory in a university. Material. Group B streptococci 090 la HD Colindale and E. coli K12, JM101. Interventions. E. coli (10(7)/mL) were grown in the absence or presence of different PFG (RM 101, PF 5080, FO 6167) for up to 6 hrs. To study bacterial viability, GBS (5 x 10(7)/mL) were incubated in saline with or without different PFC, PFC/surfactant emulsions, or surfactant (Curosurf) for up to 5 hrs. Every 2 hrs, the colony forming units were determined by plating different dilutions of bacteria on agar. Measurements and Main Results. RM 101 or PF 5080 alone and in emulsions with surfactant had no effect on viability of GBS or growth of E coli. For FO 6167, a previously described toxicity was found, even if 1 mL of GBS suspension was incubated with only 100 muL of FO 6167, verifying the experimental design that guarantees a PFC bacteria contact. The toxic effects were almost prevented by forming a PFC-in-surfactant emulsion but not by preincubation of GBS with surfactant and subsequent FO 6167 exposure. Conclusion. RM 101 and PF 5080 did not influence bacterial growth in vitro; direct effects on bacterial proliferation during partial liquid ventilation in congenital pneumonia seem, therefore, unlikely. Interestingly, we found that the known toxic effects of FO 6167 can be prevented by covering PFC with a surfactant film. Surfactant reduced the cytotoxic effects of FO 6167, probably by preventing a direct contact between FO 6167 and the bacterial cell wall
an electron microscopical and stereological study in the rat lung ; Research
No full textBackground: Repeated bronchoalveolar lavage (BAL) has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC) can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool. Methods: Male wistar rats were surfactant depleted by BAL and treated for 1 hour by conventional mechanical ventilation (Lavaged-Gas, n = 5) or partial liquid ventilation with PF 5080 (Lavaged-PF5080, n = 5). For control, 10 healthy animals with gas (Healthy-Gas, n = 5) or PF5080 filled lungs (Healthy-PF5080, n = 5) were studied. A design-based stereological approach was used for quantification of lung parenchyma and the intracellular and intraalveolar surfactant pool at the light and electron microscopic level.Results: Compared to Healthy-lungs, Lavaged-animals had more type II cells with lamellar bodies in the process of secretion and freshly secreted lamellar body-like surfactant forms in the alveoli. The fraction of alveolar epithelial surface area covered with surfactant and total intraalveolar surfactant content were significantly smaller in Lavaged-animals. Compared with Gas-filled lungs, both PF5080-groups had a significantly higher total lung volume, but no other differences. Conclusion: After BAL-induced alveolar surfactant depletion the amount of intracellularly stored surfactant is about half as high as in healthy animals. In lavaged animals short time liquid ventilation with PF5080 did not alter intra- or extracellular surfactant content or subtype composition
Effects of perfluorocarbons and perfluorocarbons/surfactant emulsions on growth and viability of group B streptococci and Escherichia coli
No full textObjective. Partial liquid ventilation with perfluorocarbons (PFG) might be used as a new ventilatory strategy to treat respiratory insufficiency in congenital pneumonia. The present study investigates for the first time effects of PFC on growth and viability of group B streptococci (GBS) and Escherichia coli, bacteria frequently causing congenital pneumonia. Design: Prospective, in vitro study. Setting: Research laboratory in a university. Material. Group B streptococci 090 la HD Colindale and E. coli K12, JM101. Interventions. E. coli (10(7)/mL) were grown in the absence or presence of different PFG (RM 101, PF 5080, FO 6167) for up to 6 hrs. To study bacterial viability, GBS (5 x 10(7)/mL) were incubated in saline with or without different PFC, PFC/surfactant emulsions, or surfactant (Curosurf) for up to 5 hrs. Every 2 hrs, the colony forming units were determined by plating different dilutions of bacteria on agar. Measurements and Main Results. RM 101 or PF 5080 alone and in emulsions with surfactant had no effect on viability of GBS or growth of E coli. For FO 6167, a previously described toxicity was found, even if 1 mL of GBS suspension was incubated with only 100 muL of FO 6167, verifying the experimental design that guarantees a PFC bacteria contact. The toxic effects were almost prevented by forming a PFC-in-surfactant emulsion but not by preincubation of GBS with surfactant and subsequent FO 6167 exposure. Conclusion. RM 101 and PF 5080 did not influence bacterial growth in vitro; direct effects on bacterial proliferation during partial liquid ventilation in congenital pneumonia seem, therefore, unlikely. Interestingly, we found that the known toxic effects of FO 6167 can be prevented by covering PFC with a surfactant film. Surfactant reduced the cytotoxic effects of FO 6167, probably by preventing a direct contact between FO 6167 and the bacterial cell wall
Perfluorocarbons are taken up by isolated type II pneumocytes and influence its lipid synthesis and secretion
No full textObjective: Because alveoli fill with perfluorocarbons during liquid ventilation, an uptake of perfluorocarbons by type II pneumocytes can be postulated that might affect synthesis and secretion of pulmonary surfactant. The study was performed to answer the following questions: Do isolated type II pneumocytes take up perfluorocarbons? Do perfluorocarbons affect lipid synthesis of type II cells? Do perfluorocarbons change surfactant secretion of type II pneumocytes? Design: Controlled experiments that used isolated type II pneumocytes. Setting., Experimental laboratory of a university hospital. Subjects: Male Wistar rats. Interventions. To study perfluorocarbon uptake, isolated type II cells were incubated with fluorescence-labeled perfluorocarbons and examined with a laser scanning microscope. The effect of perfluorocarbons on biosynthesis of phospholipids and triglycerides was measured by incubating cells that were pulse-labeled with [H-3]-palmitic acid for 30 secs, with two different perfluorocarbons (PF 5080 or RM 101) for 10 mins. The effect of perfluorocarbon incubation on lipid secretion was studied by transmission electron microscopy. To quantify secretion, adherent type II pneumocytes (containing radioactively labeled phospholipids) were incubated with perfluorocarbons, and extra- and intracellular radioactivity was measured. Measurements and Main Results., We found a significant uptake of labeled perfluorocarbons into lamellar bodies within 10 mins. Both perfluorocarbon species significantly (p <.05) reduced the biosynthesis of phospholipids when compared with control. Perfluorocarbon incubation did not affect mitochondrial activity, tested by MitoTracker staining. Transmission electron microscopy revealed changes that suggest an increased secretion of surfactant by-type II cells. Studies with radioactively labeled surfactant revealed a significantly (p <.01) higher amount of extracellular lipids after RM 101 and PF 5080 treatment (RM 101, 17 +/- 7.9%; PF 5080, 9 +/- 1.9%) compared with control (5.3 +/- 1.9%). Conclusions., Our results suggest that perfluorocarbons are taken up by type II pneumocytes and cause an increased secretion of surfactant, despite a relative reduction in the synthesis of phospholipids
Untersuchungen zur Epidemiologie der Mutter-Kind Übertragung des humanen Cytomegalievirus auf Frühgeborene und zum molekularen Mechanismus der (Re)-aktivierung des Virus während der Laktation
Full text linkIm Rahmen einer prospektiven Studie wurde die Inzidenz der Reaktivierung des Humanen Cytomegalievirus (HCMV) bei stillenden Müttern, sowie die Virusübertragung auf ihre Frühgeborenen untersucht. Mit In vitro Experimenten wurde der Einfluss von Muttermilch auf die Reaktivierung und Replikation vom HCMV untersucht. Die Muttermilch von 73 Müttern, sowie Urin- und Trachealproben ihrer 89 Frühgeborenen wurden über 2 Monate post partum wöchentlich auf HCMV DNA untersucht. Eine Reaktivierung des Virus wurde bei 95% der latent infizierten Mütter beobachtet. Zu einer Virusübertragung kam es bei 42% der HCMV-positiven Müttern auf ihre gestillten Kinder. Insgesamt infizierten sich 22 der 89 Frühgeborenen im Untersuchungszeitraum, in zwei Fällen kam es zu schweren symptomatischen Krankheitsverläufen. Infizierte Frühgeborene zeigten im Vergleich zu Nicht-Infizierten höhere Inzidenzen von Amnioninfektionssyndrom, respiratory distress syndrome und Bronchopulmonarer Dysplasie. Die Studie bestätigt ein signifikant hohes Risiko einer Übertragung von HCMV durch Muttermilch auf Frühgeborene mit teils schwerwiegendem Verlauf und eine hohe Reaktivierungsrate von HCMV in der laktierenden Brust. Daher wurde ein möglicher Einfluss von Muttermilch auf die Reaktivierung bzw. Replikation von HCMV konstatiert und der Effekt von Muttermilch auf die Aktivität des HCMV Immediate Early (IE)1/2 Enhancer/Promotors, die Virusreplikation und IE Protein Synthese in monozytären Zellen und humanen Lungenfibroblasten untersucht. Sämtliche Milchproben stimulierten den HCMV Immediate Early (IE)1/2 Enhancer/Promotor und die IE Protein Synthese in einer charakteristischen Kinetik, mit höchsten Stimulationsraten durch Molkeproben der 1.-2. Woche post partum, 2-3 Wochen vor dem Zeitpunkt der höchsten Viruslast in der Muttermilch. Durch Promotermutanten und inhibitorische Substanzen wurde gezeigt, dass die Stimulation des IE1/2 Enhancer/Promotors ein multifaktorieller Prozeß ist, an dem Glukokortikoide eine signifikante Rolle spielen.In a clinical trial, the incidence of human cytomegalovirus (HCMV) reactivation in breastfeeding mothers, virus transmission to their breastfed preterm infants and the effects of breast milk on HCMV reactivation and replication were studied. Breast milk from 73 mothers as well as urine and tracheal aspirates of their 89 infants were screened weekly for HCMV-DNA during 2 months after delivery. HCMV reactivation and virus shedding could be confirmed in 95% of latently infected mothers. Mother-to-child transmission was concluded for 42% HCMV DNA positive mothers. 22 breastfed infants acquired HCMV infection, two of them with severe symptomatic HCMV infection. The infected infants demonstrated higher incidences of amniotic infection, respiratory distress syndrome and bronchopulmonary dysplasia compared to noninfected infants. We could therefore confirm a high incidence of HCMV reactivation in lactating mothers and a significant risk of transmission to preterm infants by breastfeeding with the possibility of severe disease. The high rates of virus reactivation in mothers led us to focus on the effect of human milk on HCMV reactivation and replication in vitro: Breast milk from 12 breastfeeding mothers was tested for their effects on HCMV Immediate Early (IE)1/2 enhancer/promoter activity, viral replication and IE protein expression in monocytic cell lines and human embryonal lung fibroblasts. All milk samples stimulated HCMV IE1/2 enhancer/promoter activity und IE protein synthesis in these cell lines. The effects followed a characteristic kinetics over time: highest stimulation rates were seen with milk whey collected during the first and second week after delivery preceding the peak in viral load for 2-3 weeks. By using promoter mutants and inhibitors it could be demonstrated that stimulation of the IE1/2 enhancer/promoter is a multifactorial effect in which glucocorticoids play a significant role
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
