Rozvoj neinvazivního zobrazování cév bez užití kontrastní látky pomocí magnetické rezonance svým komerčnim debutem v roce 1990 položil základ novému perspektivnímu odvětví v rámci zobrazování magnetickou rezonancí. Oblasti dominují dvě vyšetřovací techniky - „Time of Flight'' (TOF) a „Phase Contrast" (PC). Vzájemně se převážně doplňují a spíše výjimečně si konkurují. Předmětem prvního ze série sdělení k tématu magnetické rezonanční angiografie jsou fyzikální principy a vytvoření angiografického obrazu metodou TOF. Teorie známá u nás jen z cennově nedostupných učebnic provází praktické poznámky autorů a obrazový materiál z rutinního využívání této techniky přístrojem Philips Gyroscan NT 15 (1,ST).
Non-invasive (without need for contrast agent administration) vascular imaging with the use of magnetic resonance started on commercial basis in spring 1990 and quickly became a perspective new modality alternative to invasive procedures of classical neuroradiology. Two completely different techniques of investigation dominate the field of magnetic resonance angiography (MRA) - "Time of Flight" (TOF) and "Phase Contrast" (PC), being more complementary than competitive. Basic principles and applications of TOF MRA is the topic of the first of the series of articles on MRA. The theory known from hardly accessible and expensive books comes with author's comment, own experience and images that have been done on Philips Gyroscan NT 15 (1,5 T).
Konzumace konopných drog má individuální vliv na kognitivní a psychomotorické schopnosti řidičů. Přitom pravidla, na jejichž základě by bylo možno posuzovat způsobilost či nezpůsobilost řidiče k jízdě s ohledem na hladiny kanabinoidů, nejsou jasně stanovena. V naší studii jsme se pokusili přispět k této diskuzi vlastními daty získanými od uživatelů v České republice. Předmětem studie bylo sledování hladin delta-9-tetrahydrokanabinolu (THC) v séru u rekreačních a chronických uživatelů kanabisu. Interval sledování byl bezprostředně po užití běžné dávky vlastní drogy (1 cigarety/jointa) až do 24 hodin po užití. Naše pilotní měření prokázala, že zatímco u rekreačních uživatelů prakticky nejsou detekovatelné hladiny již za 4 hodiny po užití běžné dávky, u chronických uživatelů měřitelné hladiny přetrvávají déle. V některých případech byli navíc chroničtí uživatelé prakticky permanentně pozitivní na THC. Současně však chroničtí uživatelé užili výrazně vyšší dávky, nežli uživatelé rekreační. Naše nálezy navíc dokládají velkou individuální variabilitu kinetického průběhu psychotropní látky THC v krvi díky složitým redistribučním dějům. Praktickou forenzní otázkou je, jak dlouho mohou přetrvávat psychotropní efekty THC po poslední dávce drogy. U chronických uživatelů jsou navíc literárně dobře dokumentovány indicie dlouhodobého nepříznivého ovlivnění neurokognitivních funkcí. Krevní hladina THC u řidiče sama o sobě tedy nemusí přímo dokumentovat míru ovlivnění. Řada zemí proto z preventivních důvodů ve snaze snížit rizika v dopravě přechází na „per se“ legislativu založenou na analytickém principu s minimální tolerancí k nálezu drog v krvi řidičů při jízdě.
Cannabis consumption has individual influence to cognitive and psychomotor functions of drivers and it has been generally accepted that driving under influence is risky in the perspective of traffic safety. However, rules how to assess fitness to drive are not quite clear. The psychoactive compound delta-9-tetrahydrocannabinol (THC) impairs cognition, psychomotor behaviour and driving performance in a dose-related manner approximately. After a single drug dose, THC blood concentration peaks within minutes, before the end of smoking, with a subsequent rapid decrease to the analytical limit of detection. Peak euphoria is delayed compared to THC peak blood concentration and physiological and behavioural effects return to baseline within 3-5 hours. In chronic users, the lipophilic THC accumulates in fat tissues, where its slow redistribution into blood is the rate limiting process in its terminal elimination. In our experimental study we have attempted to contribute to this discussion with results obtained from human volunteers – cannabis consumers in Czech Republic. Aim of our study was to document the time profile of serum THC level in occasional and chronic cannabis users. The observational interval covered the time immediately after the drug consumption (an own cigarette/joint) till 24 hours after. Our preliminary results have shown that in occasional users, THC serum levels cannot be detected already 4 hours after usual cannabis dose, whereas in chronic users measurable THC concentrations in serum persist longer. Moreover, some chronic consumers were practically with permanent THC detection during our observation period and also the chronic users consumed higher THC doses significantly related to doses in occasional ones. Presented results of the experimental study with human volunteers confirm a great individual variability of the kinetic profile of THC in blood due to complicated redistribution. The practical forensic question is how long the psychotropic effects of THC can persist after the last drug dose. In chronic users there are well documented indications of long term adverse effects to neurocognitive functions. THC blood level itself can not directly document the intensity of impairment of a driver. Moreover, the concentration of THC in blood at the time of driving is probably substantially higher than at the time of blood sampling. Therefore due to the prevention of traffic risk, some countries adopted per se traffic legislation based on analytical principle with minimum tolerance to illegal drugs in blood of drivers at driving. Low blood concentrations of THC close to the limit of detection of a specific toxicological method (GC-MS or LC-MS) are justified in an effective traffic legislation.
- MeSH
- Marijuana Abuse * MeSH
- Blood Chemical Analysis MeSH
- Time MeSH
- Cannabinoids * pharmacokinetics blood MeSH
- Humans MeSH
- Substance-Related Disorders MeSH
- Psychomotor Performance drug effects MeSH
- Automobile Driving * standards MeSH
- Serum MeSH
- Statistics as Topic MeSH
- Dronabinol analysis diagnostic use MeSH
- Drug Users classification MeSH
- Check Tag
- Humans MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
AIM: Platelet derivatives serve as an efficient source of natural growth factors. In the current study, α-granules were incorporated into coaxial nanofibers. MATERIALS & METHODS: A nanofiber scaffold containing α-granules was prepared by coaxial electrospinning. The biological potential of the nanofiber scaffold was evaluated in chondrocyte and mesenchymal stem cell cultivation studies. Additionally, the concentration of TGF-β1 was determined. RESULTs: Microscopy studies showed that intact α-granules were incorporated into the coaxial nanofibers. The cultivation tests showed that the novel scaffold stimulated viability and extracellular matrix production of chondrocytes and mesenchymal stem cells. In addition, the concentration of growth factors necessary for the induction of cell proliferation significantly decreased. CONCLUSION: The system preserved α-granule bioactivity and stimulated cell viability and chondrogenic differentiation of mesenchymal stem cells. Core/shell nanofibers incorporating α-granules are a promising system for tissue engineering, particularly cartilage engineering.
- MeSH
- Chondrocytes cytology drug effects MeSH
- Cytoplasmic Granules chemistry MeSH
- Microscopy, Confocal MeSH
- Cells, Cultured MeSH
- Drug Delivery Systems methods MeSH
- Humans MeSH
- Mesenchymal Stem Cells cytology drug effects MeSH
- Nanofibers chemistry MeSH
- Tissue Scaffolds chemistry MeSH
- Transforming Growth Factor beta1 MeSH
- Cell Survival drug effects MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
AIM: The rates of HIV acquired through heterosexual contact are increasing in the Czech Republic. This study explored potential HIV risk associa-tions with alcohol, illicit drugs and sexual behaviours among adults from a community-based sample attending gay- and non-gay venues in Prague. METHODS: Women attending bars, cafes and beer gardens in central Prague responded to the self-administered, time-site survey. Alcohol use was measured by the AUDIT-C and CAGE questionnaires. Sexual network structuring identified number, gender and coital frequency with current and recent sexual partners. Statistical analysis included central tendency, chi-square and logistic regression. Female participants (n=124) ranged from 18 to 67 years of age (mean 29 years); 25% self-identified as non-heterosexual. RESULTS: We found alcohol to be the preferred drug of choice. Younger heterosexual women with new and casual sexual partners were more likely to use alcohol excessively. Women with children reported the least alcohol use. Sixty percent of the sample had never used condoms; condom-use was associated with longer relationship duration and discussions about HIV status with a sexual partner; non-use tended to occur among unmarried women with multiple male partners in short, serial sexual relationships. Women who sought HIV testing tended to be younger and more self-identified as non-heterosexual. Protective practices were rarely reported even when HIV transmission increases via heterosexual sexual partnering. CONCLUSION: Further research is recommended regarding cultural and contextual influences on HIV risk behaviours among Czech women.
- MeSH
- Adult MeSH
- HIV Infections diagnosis transmission MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Alcohol Drinking epidemiology MeSH
- Substance-Related Disorders epidemiology MeSH
- Surveys and Questionnaires MeSH
- Risk-Taking MeSH
- Risk Factors MeSH
- Aged MeSH
- Sexual Behavior statistics & numerical data MeSH
- Social Behavior * MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, N.I.H., Extramural MeSH
- Geographicals
- Czech Republic MeSH
In recent years, the focus of activity behavior research has shifted away from univariate paradigms (e.g., physical activity, sedentary behavior and sleep) to a 24-h time-use paradigm that integrates all daily activity behaviors. Behaviors are analyzed relative to each other, rather than as individual entities. Compositional data analysis (CoDA) is increasingly used for the analysis of time-use data because it is intended for data that convey relative information. While CoDA has brought new understanding of how time use is associated with health, it has also raised challenges in how this methodology is applied, and how the findings are interpreted. In this paper we provide a brief overview of CoDA for time-use data, summarize current CoDA research in time-use epidemiology and discuss challenges and future directions. We use 24-h time-use diary data from Wave 6 of the Longitudinal Study of Australian Children (birth cohort, n = 3228, aged 10.9 ± 0.3 years) to demonstrate descriptive analyses of time-use compositions and how to explore the relationship between daily time use (sleep, sedentary behavior and physical activity) and a health outcome (in this example, adiposity). We illustrate how to comprehensively interpret the CoDA findings in a meaningful way.
- MeSH
- Adiposity MeSH
- Data Analysis * MeSH
- Activities of Daily Living MeSH
- Exercise * MeSH
- Child MeSH
- Cohort Studies MeSH
- Humans MeSH
- Longitudinal Studies MeSH
- Sedentary Behavior * MeSH
- Sleep MeSH
- Check Tag
- Child MeSH
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Australia MeSH
BACKGROUND: Substance abuse is considered one of the most serious society-wide problems. In our paper, we focus on leisure and the individual leisure activities which are either protective or risky in terms of substance abuse. AIMS AND OBJECTIVES: To identify the typology of users of selected addictive substances in Slovak adolescents. Another objective is to determine the differences between the identified types of substance users in their leisure time, risk activities, demographic characteristics, and family environment. METHOD: The data set was obtained through our own questionnaire to determine the frequency of substance abuse, leisure activities, demographic characteristics, and family environment of the adolescents in the target group. STATISTICAL ANALYSIS: The data was analyzed using descriptive statistics and cluster analysis. RESULTS: We identified three types of adolescents. Nearly 50% of them were non-users, approximately one third of them used all the addictive substances under study, mostly cigarettes, followed by alcohol and occasionally marijuana, and the last group was characterized by the occasional use of alcohol. Subsequently, we identified the differences between the groups in the ways they spend their leisure time. CONCLUSIONS: Occasional users of addictive substances go to discos/entertainment events, but also have temporary jobs, they use addictive substances while with their friends, and are involved in illegal activities significantly more frequently than the AS non-users. The AS non-users, in contrast, are more frequently engaged in activities such as reading books or playing board games with their parents, and they do not use addictive substances while with their friends and nor do they get involved in illegal/illicit activities.
