Search results for "MST"
showing 10 items of 363 documents
Mass accretion to young stars triggered by flaring activity in circumstellar discs
2011
Young low-mass stars are characterized by ejection of collimated outflows and by circumstellar discs which they interact with through accretion of mass. The accretion builds up the star to its final mass and is also believed to power the mass outflows, which may in turn remove the excess angular momentum from the star-disc system. However, although the process of mass accretion is a critical aspect of star formation, some of its mechanisms are still to be fully understood. A point not considered to date and relevant for the accretion process is the evidence of very energetic and frequent flaring events in these stars. Flares may easily perturb the stability of the discs, thus influencing th…
Specific distribution of cross-sectional area in each hamstring muscle of sprint runners and relationship between those and sprint performance
2018
The purpose of the present study was to examine characteristics of muscle anatomical cross-sectional area (CSA) for different regions from proximal to distal parts of each muscle of the hamstring muscles in high-level sprinters, and to examine the relationship with those and the sprint performance. The CSA of the semitendinosus (ST), semimembranosus (SM), biceps femoris long head (BFL) and biceps femoris short head (BFS) at the four different region of hamstring muscles for twenty sprinters (SPRINT) and twenty healthy male control subjects (CTRL) were measured by using B-mode ultrasonography. The measured regions were divided into four parts from proximal to distal parts (PRO1, PRO2, DIS2, …
Izglītības līmenis kā viens no iedzīvotāju demogrāfiskās uzvedības ietekmējošajiem faktoriem
2022
Latvijā dzimstība jau sen nesasniedz apmierinošu līmeni, pēdējos gados arvien vairāk samazinoties. Bet aug sieviešu ieinteresētība pēc augstākās izglītības diploma iegūšanas. Šī tendence varētu būt kā viens no cēloņiem dzimstības līmeņa samazināšanai valstī. Bakalaura darba mērķis ir noskaidrot, vai pastāv sakarība starp Latvijas iedzīvotāju izglītības līmeni un dzimstību, analizējot dzimstības ietekmējošos faktorus starp 15 - 44 gadu jaunajām Latvijas sievietēm. Izmantojot Darbaspēka apsekojuma 2020. gada datus autore konstatēja, ka starp varbūtību, ka Latvijā dzīvojošai sievietei vecumā 15 – 44 gados ir bērns līdz 18 gadiem, un sievietes pamatizglītību (vai zemāko izglītību) ir statistisk…
DNA strand break induction, mutagenicity, and cytotoxicity of the mycotoxins 11-β-hydroxy-7-deoxy-rosenonolactone, rosenonolactone, and trichothecin.
1992
11-β-hydroxy-7-deoxy-rosenonolactone (TSS1), a mycotoxin of the rosenane class, was tested on cytotoxicity, induction of DNA single strand breaks and muta-genicity. Its effects were compared to those of rosenonolactone and trichothecin. TSS1 had stronger antibiotic activity againstEscherichia coli (EC 50: 10μg/mL) than rosenonolactone (EC 50: >200μg/mL) but weaker activity than trichothecin (EC 50: 3μg/mL). The same order of activity was found for the inhibition of yeast fermentation (EC 50 of TSS1: 45μg/mL; EC 50 of rosenonolactone: > 120μg/mL; EC 50 of trichothecin: 3.4μg/mL). In the trypan blue exclusion test using V79 Chinese hamster cells, TSS1 proved to be cytotoxic (EC50: 30μg/mL) at…
Endometrial Adenocarcinoma in Syrian Hamsters Treated with Diethylstilbestrol, Tamoxifen and N-Ethyl-Nitrosourea
2006
The synthetic estrogen diethylstilbestrol (DES) causes marked abnormalities in the female hamster genital tract, after either prenatal or postnatal exposure, leading to endometrial hyperplasia and carcinoma. Acting as an initiating event, DES altering uterine development may facilitate the abnormal response of promoting agents. Tamoxifen (TAM) is an antiestrogen that competes for central and peripheral estrogen receptor (ERα). TAM exerts agonistic effects on E-dependent endometrial proliferation. N-ethyl-N-nitrosourea (ENU), a potent mutagenic agent, induces tumors in a variety of organs, predominantly in the peripheral nervous system. To test whether ENU and TAM treatment in a model of hyp…
RECRUITMENT OF BICEPS FEMORIS MUSCLE REGIONS AT DIFFERENT RUNNING SPEEDS
2017
Background The majority of hamstring strain injuries (HSIs) occur in the late swing phase of high-speed running when hamstrings work eccentrically. The proximal region of the biceps femoris (BF) seems to be the most common site of injury. Elongation of the fascicles in eccentric contractions is higher in the proximal region compared to the distal region of BF, but the neural background to this phenomenon is not clear. Objective To examine the region-specificity of BF muscle activity at different running speeds. Design Observational study. Running speeds were randomized. Setting Laboratory, amateur level. Participants Football players without acute injury/illness, and without HSI history wer…
Independent Generation of Aβ42 and Aβ38 Peptide Species by γ-Secretase
2008
Proteolytic processing of the amyloid precursor protein by beta- and gamma-secretase generates the amyloid-beta (Abeta) peptides, which are principal drug targets in Alzheimer disease therapeutics. gamma-Secretase has imprecise cleavage specificity and generates the most abundant Abeta40 and Abeta42 species together with longer and shorter peptides such as Abeta38. Several mechanisms could explain the production of multiple Abeta peptides by gamma-secretase, including sequential processing of longer into shorter Abeta peptides. A novel class of gamma-secretase modulators (GSMs) that includes some non-steroidal anti-inflammatory drugs has been shown to selectively lower Abeta42 levels withou…
Reversing agriculture from intensive to sustainable improves soil quality in a semiarid South Italian soil
2010
Intensive agriculture (IA) is widespread in South Italy, although it requires frequent tillage, large amounts of fertilizers and irrigation water. We have assessed the efficacy of reversing IA to sustainable agriculture (SA) in recovering quality of a typical South Italy soil (Lithic Haploxeralf). This reversion, lasting from 2000 to 2007, replaced 75% of nutrients formerly supplied inorganically by farmyard manuring and reduced the tillage frequency. Several chemical and biochemical properties, functionally related to C and N mineralisation–immobilisation processes and to P and S nutrient cycles, were monitored annually from 2005 to 2007 in the spring. Reversing IA to SA decreased soil bul…
Stable Expression of Heterologous Sulfotransferase in V79 Cells: Activation of Primary and Secondary Benzylic Alcohols
1994
Abstract A sulfotransferase (ST) capable of activating 1-hydroxymethylpyrene (HMP) and 9-hydroxymethylanthracene (HMA) to mutagens was purified from rat liver. This enzyme appeared to be identical with hydroxysteroid STa, whose cDNA was cloned and stably expressed in Chinese hamster V79 cells. Several primary and secondary benzylic alcohols derived from polycyclic aromatic hydrocarbons induced gene mutations, sister chromatid exchanges (SCE) and/or cytotoxicity in these cells.
Microcirculatory Dysfunction Induced by Cigarette Smoking
2000
This review deals with the deleterious effects of cigarette smoking on the microcirculation, both in terms of morphological (i.e., vessel wall injury, capillary loss) and functional aspects. The latter concerns predominantly changes in tissue perfusion and its regulatory mechanisms (i.e., reactive hyperemia, sequestration of blood cells in the microcirculation). The mechanisms of action of cigarette smoking on the microcirculation include compromised endothelial-dependent vasorelaxation, platelet aggregation, endothelial cell dysfunction, and the activation of circulating leukocytes. Through these mechanisms, cigarette smoking elicits the aggregation and adhesion of leukocytes and/or platel…