Effects of Hyperbaric Hypoxia on Some Enzyme Systems in the Mammalian Liver

The metabolic effects of hypobaric hypoxic stress on the mammalian liver were studied. The lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) activity of mouse liver homogenates were measured after exposure to an equivalent altitude of 36,000 feet and compared to controls kept at zero altitude. After six and twelve hour incubation periods, the altitude exposed samples demonstrated a significantly higher LDH activity than controls. SDH activity remained unchanged from controls after six hours but was significantly lower than controls after a 12 hour exposure to altitude. It is concluded that the changes in enzyme activity reflect a metabolic control mechanism attempting to maintain adequate energy production during periods of exposure to hypobaric hypoxic stress

Oxygen Toxicity in the Mammalian Liver

The effect of hyperbaric oxygen tensions on the oxygen consumption of mouse liver homogenates was investigated. It was found that hyperbaric oxygen rapidly inhibits the oxidative metabolism of the mammalian liver. Mouse liver homogenate exposed to an oxygen tension of 3837.8 mm Hg for 30 minutes demonstrated a 50.6% reduction in oxygen consumption compared to controls exposed to nitrogen at ambient pressure. The effects of reduced glutathione as a protective agent against hyperbaric oxygen toxicity were also examined. Liver homogenates pretreated with reduced glutathione and exposed to hyperbaric oxygen tensions demonstrated greater activity than untreated controls. It is concluded that: (1) Reduced glutathione protects important enzymes associated with oxidative metabolism by keeping them in a reduced and viable state, and (2) Reduced glutathione can stimulate oxygen consumption by increasing succinate formation through a reduced glutathione - succinate shunt

The Dutch version of the Behavior Rating Inventory of Executive Function-2 (BRIEF-2)

The BRIEF-2 (Gioia et al., 2015) is a widely used questionnaire to measure daily behavior related to executive function behaviors in the home and school environment of children between 5 and 18 years old. The current study was conducted to investigate the psychometric properties of the Dutch version of the BRIEF-2 in a representative Dutch-speaking norm sample. Using methods from classical test theory and network theory, we examined the reliability and validity of the BRIEF-2. The results indicated that the BRIEF-2 can be considered as a valid and reliable questionnaire that provides information on the role of executive function in the child’s and adolescent’s functioning in the home and school environment.</p

Determination of atmospheric mercury during the North Sea experiment

Total gaseous mercury (TGM) and rainwater were collected on board of two research vessels (F. S. ALKOR and R.V. BELGICA) positioned 200 km apart in the center of the North Sea during the North Sea Experiment, September 1991. On the F. S. ALKOR (up-wind ship) TGM concentrations ranged from 0.7 to 2.6 ng.m(-3) with an average of 1.5 ng.m(-3) and on the R. V. BELGICA (down-wind ship) TGM ranged from 0.7 to 1.9 ng.m(-3) with an average of 1.2 ng.m(-3). An average 20% decrease is observed from the up-wind to the downwind ship. which may largely be affected by entrainment into the free troposphere. An overall removal (entrainment) velocity of 0.95 cm.s(-1) was calculated for the whole experiment. The average removal velocity was 0.5 cm.s(-1) for dry periods and varied between 1 to 5 cm.s(-1) during rain events. Rainwater concentrations varied between 5 and 25 ng.l(-1). Based on these data an annual wet deposition flux of 1.08 ng Hg cm(-2) yr(1-) was estimated for the North Sea

Connectivity between migrating and landlocked populations of a diadromous fish species investigated using otolith microchemistry

Smelt Osmerus eperlanus has two different life history strategies in the Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has been in severe decline since 1990, and has strongly negatively impacted the numbers of piscivorous water birds relying on smelt as their main prey. The lakes that were formed after the dike closure, IJsselmeer and Markermeer have been assigned as Natura 2000 sites, based on their importance for (among others) piscivorous water birds. Because of the declining fresh water smelt population, the question arose whether this population is still supported by the diadromous population. Opportunities for exchange between fresh water and the sea are however limited to discharge sluices. The relationship between the diadromous and landlocked smelt population was analysed by means of otolith microchemistry. Our interpretation of otolith strontium (88Sr) patterns from smelt specimens collected in the fresh water area of Lake IJsselmeer and Markermeer, compared to those collected in the nearby marine environment, is that there is currently no evidence for a substantial contribution from the diadromous population to the spawning stock of the landlocked population

The impact of trust on private equity contracts

This paper adresses the impact of trust on private equity contracts. Trust between investor and entrepreneur is essential to help overcome control problems, especially in an environment with severe agency risks and incomplete contracts. In this study, information about the effects of trust is collected using a simulation with 144 entrepreneurs and investors. We find that trust has an impact on the desired contracts of entrepreneurs, but not on that of investors. Our findings suggest that for parties, faced with potentially large agency problems (investors), trust and control seem to play complementary roles. On the other hand, for parties faced with smaller agency problems (entrepreneurs), trust seems to be a substitute for control

Erratum to: Design of pharmaceutical products to meet future patient needs requires modification of current development paradigms and business models

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Chromosomal radiosensitivity of lymphocytes in South African breast cancer patients of different ethnicity: An indirect measure of cancer susceptibility

Background. Breast cancer is the leading cancer among South African (SA) women. SA has citizens from diverse ethnic groups, and the lifetime risk of breast cancer differs according to ethnicity. Candidate genes for increased breast cancer risk are those involved in DNA damage repair pathways, and mutations in these genes are characterised by increased chromosomal radiosensitivity. Several European studies have shown that breast cancer patients are more sensitive to ionising radiation than healthy individuals.Objectives. To investigate the in vitro chromosomal radiosensitivity of SA women with breast cancer and the possible influence of ethnicity and clinical parameters on chromosomal radiosensitivity.Methods. Chromosomal radiosensitivity was analysed with the micronucleus assay using lymphocytes of breast cancer patients and healthy individuals of different ethnic groups. Lymphocytes were irradiated in vitro with 2 Gy or 4 Gy, and micronuclei (MN) were scored 70 hours after irradiation. These MN frequencies were correlated with the ethnicity and clinical parameters of the breast cancer patients.Results. MN values were higher in breast cancer patients than in healthy controls. This was noted for black and white breast cancer patients at the different radiation doses. No correlations could be demonstrated between MN values and clinical parameters of the breast cancer, except that MN values were significantly higher in oestrogen receptor (ER)-positive breast cancers.Conclusion. SA breast cancer patients have elevated chromosomal radiosensitivity compared with healthy controls. ER positivity also influences chromosomal radiosensitivity