Hsp110 Is a Bona Fide Chaperone Using ATP to Unfold Stable Misfolded Polypeptides and Reciprocally Collaborate with Hsp70 to Solubilize Protein Aggregates

Structurally and sequence-wise, the Hsp110s belong to a subfamily of the Hsp70 chaperones. Like the classical Hsp70s, members of the Hsp110 subfamily can bind misfolding polypeptides and hydrolyze ATP. However, they apparently act as a mere subordinate nucleotide exchange factors, regulating the ability of Hsp70 to hydrolyze ATP and convert stable protein aggregates into native proteins. Using stably misfolded and aggregated polypeptides as substrates in optimized in vitro chaperone assays, we show that the human cytosolic Hsp110s (HSPH1 and HSPH2) are bona fide chaperones on their own that collaborate with Hsp40 (DNAJA1 and DNAJB1) to hydrolyze ATP and unfold and thus convert stable misfolded polypeptides into natively refolded proteins. Moreover, equimolar Hsp70 (HSPA1A) and Hsp110 (HSPH1) formed a powerful molecular machinery that optimally reactivated stable luciferase aggregates in an ATP- and DNAJA1-dependent manner, in a disaggregation mechanism whereby the two paralogous chaperones alternatively activate the release of bound unfolded polypeptide substrates from one another, leading to native protein refolding.     

Analysis of bone tissue mechanical properties

This paper deals with the torsional moment depending on the angle of torsion of the compact bone in laboratory animals and humans. Based on the data from laboratory animals, obtained by measurement, the data on dependence of the torsional moment and the angle of torsion were assumed for humans. Measurements were carried out on four groups of compact bone in laboratory animals. One was the control group, and three other groups were treated by various vitamin D3 metabolites. Equal measurements were performed in only one group of compact bone in humans, due to the impossibility to treat humans with vitamin D3 metabolites. Functional relations between the angle of torsion and the torsional moment for all groups of animal body tissue were determined by measurements, and the results were used to assume the reaction of human compact bone tissue if treated by vitamin D3 metabolites.     

Stenotic occlusive lesions of internal carotid artery in diabetic patients

Diabetes deteriorates atherosclerotic changes in the arteries. The aim of the study was to assess the prevalence and localization of stenotic atherosclerotic lesions of the internal carotid artery (ICA) in patients with diabetes. A prospective analysis of angiography findings was carried out in 150 diabetic and 150 non-diabetic patients with symptoms of cerebral ischemia using double-blind angiogram readings by two independent investigators. The degree of stenosis was determined using the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. Stenoses of the proximal arterial segment accounted for the majority of extracranial ICA stenoses, being more frequent in diabetic (left ICA 50.7%, right ICA 58.0%) than in the non-diabetic patients (left ICA 29.3%, right ICA 32.7%). Diabetic patients revealed a more significant rate of unilateral tandem ICA stenoses (14.0-21.3%), as well as a statistically significantly higher prevalence of intracranial ICA stenoses (left ICA 24.0% and right ICA 17.3%) than did non-diabetic patients (left and right ICA 3.3% each). Our results confirm that there is a morphological basis in ICA for increased incidence of ICA lesions in patients with diabetes as compared to those without it. Data on the incidence of stenotic ICA lesions in diabetes suggest the importance of assessing overall ICA status using digital subtraction angiography. Such an assessment is a precondition for an optimal therapeutic approach, especially in diabetic patients who are at an increased risk of cerebrovascular disease.     

Essential oil composition of Hypericum L. species from Southeastern Serbia and their chemotaxonomy

The essential oils of the aerial parts of nine species of Hypericum (Hypericum barbatum, Hypericum hirsutum, Hypericum linarioides, Hypericum maculatum, Hypericum olympicum, Hypericum perforatum, Hypericum richeri, Hypericum rumeliacum and Hypericum tetrapterum), collected from different locations in Southeast Serbia, were obtained by steam distillation and analyzed by GC and GC–MS. The essential oils investigated were characterized by a high content of non-terpene compounds and a low content of monoterpenes. The contents of non-terpenes, monoterpenes and sesquiterpenes in oils of the species H. barbatum, H. richeri and H. rumeliacum (section Drosocaprium) were similar and these oils were characterized by high contents of fatty acids. The oils of H. hirsutum and H. linarioides (section Taeniocarpium) contained a high percentage of n-nonane. There were similarities in contents of non-terpenes and sesquiterpenes in oils of species that belong to the section Hypericum (H. maculatum, H. perforatum and H. tetrapterum). The oil of H. olympicum differed from others by higher terpene content. A comparison was also carried out of the chemical composition of the essential oils from flower, leaf and stem of H. perforatum and it revealed that the highest concentration of non-terpene compounds was found in the flower and stem oil, while a high concentration of sesquiterpenes was characteristic for leaf oil. There were significant differences in the concentrations of the same compounds in the essential oils of H. maculatum, H. olympicum and H. perforatum, collected in different years from the same location which could be explained by seasonal differences. All data were statistically processed with principal component analysis and cluster analysis. The main conclusion from the above data is that genetic and environmental factors both play a role in determining the composition of essential oils of the Hypericum species studied.     

Parkinson Patients’ Initial Trust in Avatars: Theory and Evidence

Parkinson’s disease (PD) is a neurodegenerative disease that affects the motor system and cognitive and behavioral functions. Due to these impairments, PD patients also have problems in using the computer. However, using computers and the Internet could help these patients to overcome social isolation and enhance information search. Specifically, avatars (defined as virtual representations of humans) are increasingly used in online environments to enhance human-computer interaction by simulating face-to-face interaction. Our laboratory experiment investigated how PD patients behave in a trust game played with human and avatar counterparts, and we compared this behavior to the behavior of age, income, education and gender matched healthy controls. The results of our study show that PD patients trust avatar faces significantly more than human faces. Moreover, there was no significant difference between initial trust of PD patients and healthy controls in avatar faces, while PD patients trusted human faces significantly less than healthy controls. Our data suggests that PD patients’ interaction with avatars may constitute an effective way of communication in situations in which trust is required (e.g., a physician recommends intake of medication). We discuss the implications of these results for several areas of human-computer interaction and neurological research.     

A 10-year experience in the treatment of intraabdominal cerebrospinal fluid pseudocysts

The aim of this retrospective study was to assess a ten-year experience in the treatment of rare complications of ventriculoperitoneal shunting--intraabdominal cerebrospinal fluid pseudocysts. At this time there are no data about incidence, clinical course and treatment of these complications in Croatia. Cerebrospinal fluid (CSF) abdominal pseudocyst is an uncommon but important complication of ventriculoperitoneal shunts. Retrospective data were obtained from 5 children with abdominal CSF pseudocysts, treated between 1996 and 2007. The incidence of intraabdominal CSF pseudocysts in our study is 2.9%. All patients were girls ranged in age from 4 to 12 years old (mean 8.8 years). In most cases etiology of hydrocephalus was congenital, idiopathic. Abdominal pain and distension were the most frequent clinical finding (4/5). Although infection has been reported as responsible for pseudocyst formation, we did not found it in our series. Laparotomy with cyst wall excision and catheter replacement was performed in 2/5 cases, and only cyst fluid aspiration with catheter replacement in 3/5 cases. Recurrence of the abdominal cyst was observed in one girl who was in terminal stadium of anaplastic ependymoma. It is our opinion that only catheter replacement and cyst fluid evacuation, as one of the treatment modalities, may be successful, even in large CSF intraperitoneal pseudocysts.     

The yeast Ccr4-Not complex controls ubiquitination of the nascent-associated polypeptide (NAC-EGD) complex

In this work, we determine that the Saccharomyces cerevisiae Ccr4-Not complex controls ubiquitination of the conserved ribosome-associated heterodimeric EGD (enhancer of Gal4p DNA binding) complex, which consists of the Egd1p and Egd2p subunits in yeast and is named NAC (nascent polypeptide-associated complex) in mammals. We show that the EGD complex subunits are ubiquitinated proteins, whose ubiquitination status is regulated during cell growth. Egd2p has a UBA domain that is not essential for interaction with Egd1p but is required for stability of Egd2p and Egd1p. Ubiquitination of Egd1p requires Not4p. Ubiquitination of Egd2p also requires Not4p, an intact Not4p RING finger domain, and all other subunits of the Ccr4-Not complex tested. In the absence of Not4p, Egd2p mislocalizes to punctuate structures. Finally, the EGD complex can be ubiquitinated in vitro by Not4p and Ubc4p, one of the E2 enzymes with which Not4p can interact. Taken together our results reveal that the EGD ribosome-associated complex is ubiquitinated in a regulated manner, and they show a new role for the Ccr4-Not complex in this ubiquitination.     

The knock-out of ARP3a gene affects F-actin cytoskeleton organization altering cellular tip growth, morphology and development in moss Physcomitrella patens

The seven subunit Arp2/3 complex is a highly conserved nucleation factor of actin microfilaments. We have isolated the genomic sequence encoding a putative Arp3a protein of the moss Physcomitrella patens. The disruption of this ARP3A gene by allele replacement has generated loss-of-function mutants displaying a complex developmental phenotype. The loss-of function of ARP3A gene results in shortened, almost cubic chloronemal cells displaying affected tip growth and lacking differentiation to caulonemal cells. In moss arp3a mutants, buds differentiate directly from chloronemata to form stunted leafy shoots having differentiated leaves similar to wild type. Yet, rhizoids never differentiate from stem epidermal cells. To characterize the F-actin organization in the arp3a-mutated cells, we disrupted ARP3A gene in the previously described HGT1 strain expressing conditionally the GFP-talin marker. In vivo observation of the F-actin cytoskeleton during P. patens development demonstrated that loss-of-function of Arp3a is associated with the disappearance of specific F-actin cortical structures associated with the establishment of localized cellular growth domains. Finally, we show that constitutive expression of the P. patens Arp3a and its Arabidopsis thaliana orthologs efficiently complement the mutated phenotype indicating a high degree of evolutionary conservation of the Arp3 function in land plants.     

Comfort evaluation as the example of anthropotechnical furniture design

Human health is becoming an increasingly important issue in contemporary hectic lifestyle imposed at work and by struggle to save time and money. Sitting comfort and quality of chairs which we use for the most of our time have, thus, become essential for healthy lifestyle. Sitting discomforts arise from prolonged sitting on the inappropriate chairs, which failing to provide sufficient support to the body cause discomfort and tiring. The studies of the office chair constructions have identified differences in perception of comfort provided by different types of seats. Four seat constructions and the comfort they provide to the sitters were compared by means of subjective indicators. After a two-day sitting on each of the studied chairs the subjects scored their perception of comfort and discomfort, using the questionnaire with 17 statements. Constructional forms and materials which contributed more to the sense of comfort by minimizing fatigue and pains developed by sitting were determined.