Exploring the role of galectin 3 in kidney function: a genetic approach

Galectin 3 belongs to a family of glycoconjugate-binding proteinsthat participate in cellular homeostasis by modulating cellgrowth, adhesion, and signaling. We studied adult galectin 3null mutant (Gal 3–/–) and wild-type (WT) mice togain insights into the role of galectin 3 in the kidney. Byimmunofluorescence, galectin 3 was found in collecting duct(CD) principal and intercalated cells in some regions of thekidney, as well as in the thick ascending limbs at lower levels.Compared to WT mice, Gal 3–/– mice had ~11% fewerglomeruli (p < 0.04), associated with kidney hypertrophy(p < 0.006). In clearance experiments, urinary chloride excretionwas found to be higher in Gal 3–/– than in WT mice(p < 0.04), but there was no difference in urinary bicarbonateexcretion, in glomerular filtration, or urinary flow rates.Under chronic low sodium diet, Gal 3–/– mice hadlower extracellular fluid (ECF) volume than WT mice (p <0.05). Plasma aldosterone concentration was higher in Gal 3–/–than in WT mice (p < 0.04), which probably caused the observedincrease in -epithelial sodium channel (-ENaC) protein abundancein the mutant mice (p < 0.001). Chronic high sodium dietresulted paradoxically in lower blood pressure (p < 0.01)in Gal 3–/– than in WT. We conclude that Gal 3–/–mice have mild renal chloride loss, which causes chronic ECFvolume contraction and reduced blood pressure levels.     

Development of captive bongos (Tragelaphus eurycerus): Activity budgets and developmental milestones

The development of changes in visual orientation, posture, activity budgets, and behavioral milestones was examined in five bongo calves which were observed from birth to 4 or 6 months of age. The only significant change in the calves' visual orientation was an increase in orientation to food. Reclining declined significantly over weeks, while standing increased and moving did not change. Overall, stationary behaviors dominated the activity budget, but decreased significantly over the study. The category that included locomotion, object exploration, and auto-play did not change, while forage and rumination increased significantly. Contrary to expectation, the decline in suckling was not significant. Affiliative interactions with the dam decreased significantly during the study, but increases in affiliation with other bongos were not significant. Levels of agonistic behavior between the calves and their dams and other herd members were low throughout the study, and did not change significantly. One female calf achieved several developmental milestones later than the others. It is suggested that these differences may have been influenced by the dominance status of her dam. The results conform to the general developmental pattern of “hider” bovids. Bongos, however, show somewhat different patterns of social development than eland, which are reported to be more precocial in expression of aggressive and sexual behaviors. © 1992 Wiley-Liss, Inc.     

Omgaan met somberheid op oudere leeftijd: een kwalitatieve studie

Background

To gain new insights for support for older people with low mood, we explored the perceptions of ‘screenpositive’ older people on underlying causes and possible solutions.

Design and method

We conducted two in-depth interviews with 38 participants (≥77 years) who screened positive for depressive symptoms in general practice. To investigate the influence of the presence of complex health problems, we included 19 persons with and 19 without complex problems. Complex problems were defined as a combination of functional, somatic, psychological or social problems.

Results

All participants used several cognitive, social or practical coping strategies. Four patterns emerged: mastery, acceptance, ambivalence, and need for support. Some participants, especially those with complex problems, were ambivalent about possible interventions.

Conclusion

Most older participants perceived their coping strategies as sufficient. General practitioners can support self-management by exploring the (effectiveness of) personal coping strategies, providing information, elaborating on perceptions of risks and discussing alternative options with older persons.

     

Oligomerization and phase transitions in aqueous solutions of native and truncated human beta B1-crystallin

Human betaB1-crystallin is a major eye-lens protein that undergoes in vivo truncation at the N-terminus with aging. By studying native betaB1 and truncated betaB1DeltaN41, which mimics an age-related in vivo truncation, we have determined quantitatively the effect of truncation on the oligomerization and phase transition properties of betaB1 aqueous solutions. The oligomerization studies show that the energy of attraction between the betaB1DeltaN41 proteins is about 10% greater than that of the betaB1 proteins. We have found that betaB1DeltaN41 aqueous solutions undergo two distinct types of phase transitions. The first phase transition involves an initial formation of thin rodlike assemblies, which then evolve to form crystals. The induction time for the formation of rodlike assemblies is sensitive to oligomerization. The second phase transition can be described as liquid-liquid phase separation (LLPS) accompanied by gelation within the protein-rich phase. We refer to this process as heterogeneous gelation. These two phase transitions are not observed in the case of betaB1 aqueous solutions. However, upon the addition of poly(ethylene glycol) (PEG), we observe heterogeneous gelation also for betaB1. Our PEG experiments allow us to estimate the difference in phase separation temperatures between betaB1 and betaB1DeltaN41. This difference is consistent with the increase in energy of attraction found in our oligomerization studies. Our work suggests that truncation is a cataractogenic modification since it favors protein condensation and the consequent formation of light scattering elements, and highlights the importance of the N-terminus of betaB1 in maintaining lens transparency.