Feedback inhibition of bile acid synthesis in cultured pig hepatocytes

Bile acid synthesis by cultured pig hepatocytes, as measured by conversion of [14C]cholesterol to bile acids, increased during the second and third day of culture. This rise was inhibited after addition of various conjugated and unconjugated bile acids in a concentration of 100 microM. It could be completely prevented by cycloheximide, indicating that de novo protein synthesis is required for the increase in bile acid formation. No effect of exogenous bile salts on LDH release to the medium or on cellular ATP content was observed, demonstrating that hepatocyte viability was not affected. During the period in which bile acid synthesis was inhibited, pig hepatocytes were able to accumulate taurocholic acid (100 microM) up to 7-18 nmol per mg cell protein (decreasing during culture time). It is concluded that feedback regulation of bile acid synthesis is exerted by direct action of bile acids on the hepatocyte.     

Binding of low-density lipoprotein to heparin-Sepharose: characterization and inhibition by serum high-molecular-weight components

In this study, the interaction of human serum low-density lipoprotein (LDL) with heparin immobilized on Sepharose was reinvestigated. Binding of isolated LDL (stabilized with human serum albumin (HSA] was compared with that of LDL in full serum. (1) Binding of isolated LDL was slightly decreased by CaCl2 and was not affected by MgCl2. In contrast, with full serum LDL binding was increased by these divalent cations. (2) In both situations, binding of LDL was saturable, but the maximum degree of binding that could be reached was much higher with isolated LDL than with LDL in full serum. This could be ascribed to an inhibitory action of a factor found in the d greater than 1.24 fraction of serum. (3) The effect of this factor was diminished in the presence of CaCl2 or MgCl2, which suggests that the stimulation of LDL binding by these cations in full serum is due to suppression of the inhibitory activity of this factor. (4) The inhibitory factor in the d greater than 1.24 fraction can be partially purified by absorption to heparin-Sepharose, followed by elution with 6 M guanidine chloride. The resulting preparation had a 30- to 50-fold higher specific activity. Attempts to purify the factor further resulted in loss of activity. (5) The activity is decreased upon treatment with trypsin and also upon acetylation or reduction with dithiothreitol, indicating that free amino groups and S-S bridges are essential.     

Quantitative determination of phenolsulfotransferase using 4-methylumbelliferone

The method presented here offers a rapid and reproducible technique for assay of the enzymic formation of MUS from MU, as use is made of the extremely intensive fluorescence of MU and of the possibility of quantitative separation of the product formed from the substrate by use of ion-exchange chromatography.     

Gas exchange patterns of Pterostichus niger (Carabidae) in dry and moist air

Gas exchange patterns of adult male Pterostichus niger Schaller after hydration (i.e. given access to food and water) are compared in dry air [5–7% relative humidity (RH)] and moist air (90–97% RH) by means of flow‐through CO₂ respirometry combined with infrared probe actography. Of thirty beetles examined, slightly more than 50% showed continuous gas exchange and are not considered further. Of the remaining beetles, the majority (approximately 71%) display a pattern of cyclic gas exchange in both dry and moist air (i.e. CO₂ gas is released in bursts, with a low level of CO₂ release during the interburst periods). A minority of the beetles (four out of 30) are found to exhibit discontinuous gas exchange in both dry and moist air; this is characterized by three clearly separated states of the spiracles: closed (C), flutter (F) and open (O) phases. The pattern of cyclic gas exchange is associated with weak abdominal pulsations. After switching from moist to dry air, a small modulation of the discontinuous gas exchange cycles (maximum mean CO₂ production rate) occurs, providing no clear support for the hygric theory of discontinuous gas exchange in this species (i.e. that it serves to restrict respiratory water loss).     

Protandrous migration and variation in morphological characters in Emberiza buntings at an East Asian stopover site

The effect of the timing of spring migration on reproductive success differs between the sexes. As a consequence, various sex‐specific tactics relating to the timing of migration have evolved in migratory avian groups. Various hypotheses have been proposed to explain differential migration to breeding or wintering grounds, and inter‐ and intrasexual size differences are often considered one of the proximate mechanisms. We investigated arrival patterns in the spring by individuals of each sex, sexual size dimorphism and related morphological variables, and the relationship between size variation and arrival date in five bunting species that passed through an East Asian migratory flyway stopover site in 2006–08. Males of all the study species arrived before females, and significant sexual dimorphism was observed. Several morphological characters, including total length, wing‐length and tail‐length, contributed to the size variation. Although larger males arrived earlier, there was no relationship between arrival date and size in females. Our study confirmed that East Asian buntings display a discriminated protandrous migration pattern at the stopover site as well as at the breeding grounds. This is consistent with the view that larger body size in males is favoured due to its association with early arrival to help ensure access to the best resources and hence enhanced mating success.     

Het verklaren van verschillen in ervaren kwaliteit van leven van kwetsbare ouderen: een ‘mixed-method’ onderzoek

Most research on (multidimensional) frailty focuses on deficits and risks of adverse outcomes. However, frail older people can still report positive outcomes, such as a relatively high QoL. In order to develop more positively oriented prevention strategies, this exploratory study aimed (a) to identify characteristics related to QoL among frail older people; and (b) to explain discrepancies between higher and lower levels of QoL, with a specific focus on strengths frail older people with a higher QoL still may have. Quantitative and qualitative data was gathered by means of semi-structured interviews with Flemish community-dwelling, frail older people with higher (n?=?16) and lower QoL levels (n?=?18). Quantitative analyses showed that frail older people with a higher QoL were older, had lower levels of psychological frailty, and reported higher meaning in life compared to those with a lower QoL. Outcomes of qualitative analysis showed that participants in the high QoL subgroup adapted more effectively to difficulties, had more things in prospect, performed more activities, and were more satisfied with their social network compared to the low QoL subgroup. To conclude, this exploratory study suggests possibilities to promote and improve QoL by strengthening specific resources among frail older people.Please note that an English version of this article has been published in BMC Geriatrics: van der Vorst A, Zijlstra GAR, De Witte N, Vogel RGM, Schols JMGA, Kempen GIJM, D?SCOPE Consortium. Explaining discrepancies in self-reported quality of life in frail older people: a mixed-methods study. BMC Geriatr. 2017;17(1): 251.  https://doi.org/10.1186/s12877-017-0641-y.     

Telefonisch Interview Cognitieve Status (TICS): psychometrische aspecten

The psychometric properties of the Dutch version of the Telephone Interview Cognitive Status (TICS). The Telephone Interview Cognitive Status (TICS) is an instrument to screen for dementia in older persons by telephone. Although the psychometric properties of the TICS have been studied in various countries, the quality of the Dutch version of the TICS was yet unknown. This paper presents the Dutch version of the TICS and reports on its reliability and validity among 51 patients of Maastricht University Hospital, the Netherlands. The Pearson and intra-class correlations for test-retest reliability were 0,93 and 0,92, respectively. The Pearson and intra-class correlations for inter-rater reliability were 0,91 and 0,90, respectively. Sensitivity and specificity were studied in relation to the Mini Mental State Examination (MMSE, cut-off point 23/24) and the diagnosis of dementia as assessed according to DSM-IV criteria. When using the TICS cut-off point of 26/27, the coefficients for sensitivity and specificity were at least 0,80. The percentages ROC under the curve were 90% and 93% with the MMSE and the diagnosis dementia as criterion, respectively. We conclude that the Dutch version of the TICS is an acceptable instrument for screening for dementia in older persons, particularly when face-to-face contact is not possible.