bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling of Queue Length in Freeway Work Zones – Case Study Karaj-Tehran Freeway
Authors: Mousazadeh Gilandeh Mojtaba , Ali Sari Sharif , Goodarzi Mohammad Javad , Amini Nahid , Latifi Hassan
Published: February 2021

In this study, the traffic parameters were collected from three work zones in Iran in order to evaluate the queue length in the work zones. The work zones were observed at peak and non-peak hours. The results showed that abrupt changes in Freeway Free Speed (FFS) and arrival flow rate caused shockwaves and created a bottleneck in that section of the freeway. In addition, acceleration reduction, abrupt change in the shockwave speed, abrupt change in the arrival flow rate and increase in the percentage of heavy vehicles have led to extreme queue lengths and delay. It has been found that using daily traffic data for scheduling the maintenance and rehabilitation projects could diminish the queue length and delay. Also, by determining the bypass for heavy vehicles, the delay can be significantly reduced; by more than three times. Finally, three models have been presented for estimating the queue length in freeway work zones. Moreover, the procedure shown for creating a queue length model can be used for similar freeways.
Collaborative Optimization of Car-flow Organization for Freight Trains Based on Adjacent Technical Stations
Authors: Yang Yijing , Wu Xu , Li Haonan
Published: February 2021

This paper proposes a collaborative optimization model of car-flow organization for freight trains based on adjacent technical stations to minimize the average dwell time of train cars in a yard. To solve the car-flow organization problems, a priority-based hump sequence, which depends on the cars available in two adjacent technical stations, is adopted. Furthermore, a meta-heuristic algorithm based on the genetic algorithm and the taboo search algorithm is adopted to solve the model, and the introduction of the active scheduling method improves the efficiency of the algorithm. Finally, the model is applied to the car-flow organization problem of two adjacent technical stations, and the results are compared with those from a single technical station without collaboration. The results demonstrate that collaborative car-flow organization between technical stations significantly reduces the average dwell time at the stations, thereby improving the utilization rate of railroad equipment. In addition, the results indicate that the hybrid genetic algorithm can rapidly determine the train hump and marshalling schemes.
An Alternative Source of Development for Local Governments: Local Literacy
Authors: Guven Bulent
Published: February 2021

Local literacy could be defined as a process of gaining skills for the recognition of local assets, historical sites, places and literary works, which are important for countries in a national and spiritual sense (historical, cultural, touristic, economic, etc.) in the areas where citizens live, being aware of the basic characteristics of the local habitat, and when necessary, reporting the gained knowledge and skills to other people through presentations appropriately prepared (Güven, 2019). This conceptual article discusses opinions and suggestions about the introduction of local literacy skills, which are considered very necessary and profitable for local governments, education and training institutions. It also discusses the contributions provided with the gain of local literacy skills to local governments. The article presents ways in which students can be supported to learn about and adopt the material and spiritual items with a certain value, the individuals and institutions that provide community benefits, sites, natural resources, and the richness around them. Local governments are also provided with some considerations and suggestions about local literacy, which is considered necessary for local governments, and their contributions to local governments as an incentive to invest.
Evaluating Students’ Final Text Production in Polyphonic Critical Literacy Practices: Combining Appraisal Theory with Qualitative Data Sources
Authors: Sipitanos Konstantinos
Published: February 2021

Critical literacy practices have moved their interest from Freirean binary analyses (e.g. oppressor versus oppressed) to more complex perspectives, where in a text the author/speaker is (dis) aligned with different discourse communities. Despite the fact that these teaching practices that are based in multiple discources are gaining attention, little work has been done on the assessment of the teaching practices. During the last decades, the literacy activities researches have focused on the teacher-student interactions and the teacher talks (asking questions, types of questions), neglecting the final text production, which is also a significant factor in the evaluation of literacy practices. In this paper, after the implementation of polyphonic literacy practices in a rural junior high school in Crete, Greece, the teacher-researcher assessed the final student written products using the Appraisal Theory. Further qualitative methodological data gathering sources enhanced the identification of the contextual factors that can explain in depth the discourses the students (re)produced in their texts. These findings suggest that Appraisal Theory combined with such methodological choices, where the context is identified, is more supportive in the evaluation of these complex critical literacy practices and provides the teacher and students fruitful feedback concerning critical literacy awareness.
Effects of Instructional Materials used at the Community Learning Resource Centers on Adult Learners’ Participation in Community Development Activities in Nyamira North Sub-county Kenya
Authors: Bella Benjamin Obonyo , Koome Peter , Kamuru Susan
Published: February 2021

This research sought to investigate the effects of instructional materials used at community resource centers on adult literacy learners in community development activities with a specific focus on Nyamira North Sub–County, Kenya. The study was guided by the constructivism theory of learning. It employed the descriptive survey design where a sample of 254 learners was drawn from a population of 492 adult learners in the study area using the stratified random sampling method. Questionnaires were administered to elicit information from the respondents. The collected data were analyzed using descriptive statistical methods. From the findings, there was a clear indication that textbooks and sewing machines were more available and adequately utilized. Other resources like computers, projectors, ovens, banana ripening chambers, and videos were least available and inadequate. Results further showed that most of the adult learners were involved in small-scale farming as their main economic activity with most of their products was selling them to the market in raw form. Some learners were also involved in natural resource management activities with the majority of them planting trees, water resources management, bridges, and path construction. The study recommended that to diversify the livelihoods of the communities in the study area, the Directorate of Adult Education should provide diverse instructional materials such as ICT facilities and equipment that which will impart value addition skills to the learners.
An Evaluation of Pre-Service Teachers’ Competences and Views Regarding Inclusive Education
Authors: Şahan Gülsün
Published: February 2021

Inclusive education is a form of education in which individuals with any disabilities receive education together with their peers. The education people with disabilities receive in special classrooms by expert teachers has begun to be conducted as inclusive education in normal classrooms by non-expert teachers. Senior class pre-service teachers take the special education course in education faculty and also primary school pre-service teachers receive the ınclusive education course in addition to this course. The aim of this research is to determine the opinions of the pre-service teachers who receive the special education courses about the adequacy of inclusive education and special education practices they observe at schools. The research was prepared in a mixed pattern and quantitative and qualitative techniques were used together. Therefore, Teacher Competence Scale in Inclusive Applications developed by Bayar (2015) was applied to 197 students who study science, mathematics, social studies, Turkish and, primary school teaching. Besides, views of 25 pre-service teachers who study in the same classes were collected and evaluated in written form. At the end of the study, it was determined that while Science pre-service teachers consider themselves more competent in inclusion, primary school pre-service teachers have higher classroom management competence. There is not any significant difference between pre-service teachers’ views about inclusive education according to gender. Furthermore, the pre-service teachers think that teachers lack knowledge and education, students’ disabilities are not recognized, there is a lack of equipment, and cooperation of school and family is not effective.
Effect of Teachers’ Self-Efficacy on their Attitude towards the Implementation of Multicultural Education literacy in Harari Government Secondary Schools
Authors: Tezera Debela , Bekele Gadissa
Published: February 2021

This study is aimed to investigate effect of teachers’ self-efficacy on their attitude towards the implementation of Multicultural Education literacy (MCEL) in Harari Region Secondary Schools. To realize this descriptive survey design with the quantitative approach is adopted. One hundred, teachers are selected by using stratified random sampling technique and then the simple random sampling technique. Data are collected through closed-ended questionnaires. Descriptive and inferential statistical data analysis is employed. The finding showed that the practice of MCEL in school was medium and teachers’ self-efficacy toward implementations of MCEL in the schools was found statistically significant. Self-efficacy in the implementation of MCEL was a statistically significant predictor of teacher’s attitude and practices toward the implementation of MCEL in the schools respectively. Self-efficacy contributed 17% on attitude and 26 % to practices in the implementation of MCEL had a positive impact. Self-efficacy of teachers toward MCEL had a statistically significant moderate positive relationship with teachers’ practices of MCEL. Self-efficacy had a positive impact on the attitude of teachers and practices of teachers in the implementation of MCEL. Based on the findings, it was concluded the study presented for further research in the field and policy action to prepare teachers in multicultural setting curricula and multicultural educators influencing the development of cultural tolerance, mutual understanding, and unity among diverse students. Hence, it was recommended that organizing panel discussion in order to improve self-efficacy and attitude of teachers from multicultural perspectives in line with implementation of multicultural education through media to build tolerance, mutual respect, build positive attitudes, and national building practices among student in the schools. Further implications and directions for future study are forwarded.
Determination of Reinforcement Usage Strategies during Literacy Education of Teachers Working with Students with Multiple Disabilities in Turkey
Authors: Çetin Müzeyyen Eldeni̇z
Published: February 2021

In this study, it is aimed to determine the opinions of teachers working with students with multiple disabilities about the way in which they determine and use reinforcements during literacy education. The research was designed based on the qualitative research design, and the data was collected from 5 male and 15 female teachers using the semi-structured interview technique. The data obtained from the interviews were analyzed using the descriptive analysis technique. As a result of the research, it was found that teachers working with students with multiple disabilities mostly stated that the use of reinforcers is important. They also emphasized that their use also motivates students, helps them to gain positive behavior, and makes education effective and permanent. Most of the teachers expressed that they make observations while determining the reinforcement suitable for their students. It was found that the teachers used the observations to take the interests, needs, likes and wishes of their students into account. It was discovered that they mostly determined the effect of the reinforcer they used for students through observation and that teachers preferred food and beverage, activity, symbol, toy and game reinforcers in general. It was revealed that teachers working with students with multiple disabilities use observation method in determining the reinforcers for their students and evaluate their effects and that they do not use other methods. Moreover, they do not give much room to use and diminish reinforcement tariffs.
Teacher Candidates’ Opinions about the Use of Museums as Educational Environments in Social Studies Lessons
Authors: Uslu Salih
Published: February 2021

The aim of this study is to determine the opinions of teacher candidates regarding the use of museums in social studies lessons as an educational environment. The study group of the research was determined through purposeful sampling method. The study group consists of 114 teacher candidates studying in the social sciences teaching department at the education faculty of a public university during the 2019-2020 academic year. In this case study, a personal information form and an open-ended question form developed by the researcher were used as data collection tools. The data obtained from the answers given by teacher candidates to the data collection tools were analysed by using content analysis method. When the research results were examined in general, it was seen that Social Studies Teacher Candidates mostly explained the benefits that using museums as an educational environment were “ensuring permanent learning”, “enabling students to learn better by seeing/living” and “providing information about the past”. According to another result obtained from the research, Social Studies Teacher Candidates based the problems that they might face while using museums as an educational environment on “the possibility that students may give harm to historical documents and objects”, “financial impossibilities” and “difficult to control the classroom”.
The Views of Turkish Language Teachers on Distance Education and Digital Literacy during Covid-19 Pandemic
Authors: Aydin Erkan , Erol Sedat
Published: February 2021

Distance education, which provides flexibility in the learning environment, is an important learning model that complements face-to-face education. However, during the unanticipated Covid-19 pandemic, the distance education model was employed as an alternative instruction model, albeit temporarily, and certain problems were experienced in this process. In this context, the views of the Turkish language teachers on distance education and digital literacy in Turkey, where average population is quite young and the impact of the pandemic was substantial, was investigated in the present study. The study was conducted with the phenomenological design, a qualitative research method, and the study group included middle school Turkish language teachers who conducted distance education during the four months of the pandemic process. In the study, a semi-structured interview form, developed by the authors, was employed as the data collection instrument, and the collected data were analyzed with content analysis. The study findings revealed problems such as student attendance; digital problems such as Internet connectivity, infrastructure, and system; interaction, interest and commitment; literacy problems such as inability of distance education to improve written expression skills of the students; inadequate synchronous/online class count and duration, and poor parent-student-teacher cooperation. Based on these findings, it was recommended to design multimedia material that allow bidirectional interaction and improve inter-institutional cooperation to solve digital problems.
Literacy: Gateway to a World of Exploits
Authors: Zua Biale
Published: February 2021

The importance of literacy to the personal development of an individual and existence of any nation cannot be overemphasized. Literacy is the foundation for meaningful development of any nation. It is not a single entity but an interconnection of several fields―education, health, agriculture, and more. For example, a literate individual can have access to information relating to her career or business. However, not every individual in the society is literate enough to contribute to national development. Thus, strong literacy skills are necessary to function in today’s contemporary society. This research examines literacy across African countries with a view of determining countries with high literacy rates. Countries in sub-Saharan Africa have low literacy rates with gender and regional disparity. Therefore, sub-Saharan Africa national governments need to develop strong literacy skills in their countries to participate effectively in the globalized society.
Anaplerotic reactions in Anabaena cylindrica
Authors: Neuer Gabriele , Bothe Hermann
Published: July 2002

Anaplerotic reactions occur in heterocysts and vegetative cells of Anabaena cylindrica. This cyanobacterium possesses phosphoenolpyruvate carboxylase and malic enzyme, but no pyruvate carboxylase and isocitrate lyase. Heterocysts contain all the enzymes for the conversion of glucose 6‐phosphate to oxoglutarate and may not be dependent on a supply with glutamate from vegetative cells.
Target size analysis of skeletal muscle Ca2+ channels
Authors: Goll A. , Ferry D.R. , Glossmann H.
Published: July 2002

[3H]PN 200‐110, a potent chiral benzoxadiazol 1,4‐dihydropyridine Ca2+ antagonist was used to label guinea pig skeletal muscle Ca2+ channels. [3H]PN 200‐110 binds with a K
d of ∼1 nM to a homogeneous population of non‐interacting binding sites; d‐cis‐diltiazem, but not 1‐cis‐diltiazem increases the B
max of [3H]PN 200‐110 by 25% and slows the dissociation rate 3‐fold at 37°C. Target size analysis of the [3H]PN 200‐110‐labelled Ca2+ channels with 10 MeV electrons gave an M
r of 136 000 which was reduced to 75 000 by d‐cis‐diltiazem treatment of membranes. It is concluded that positive heterotropic allosteric regulation by d‐cis‐diltiazem is accompanied by channel oligomer dissociation.
Primary structure of a high Mr form of rat atrial natriuretic factor
Authors: Thibault G. , Garcia R. , Cantin M. , Genest J. , Lazure C. , Seidah N.G. , Chrétien M.
Published: July 2002

During the purification of rat atrial natriuretic factor (ANF), low, intermediate and high M
r forms were observed. In this report we describe the purification and amino acid sequence of a 73 residue peptide containing at its C‐terminus the previously sequenced 33 amino acid ANF peptide. The cleabage necessary to produce the 33 amino acid ANF from the 73 amino acid precursor occurs at a LeuLeu bond. We also report the amino acid composition of an even longer form of ANF containing about 103 residues, in which the extension is amino terminal to the 73 peptide. A computer data bank search showed that the determined sequence is a novel one and is not homologous to any known proteins or segment thereof. The natriuretic activity of the 73 amino acid form when compared to that of a synthetic ANF peptide, comprising the sequence of the last 26 amino acids of ANF, was found to be slightly lower.
Phosphoinositide breakdown in isolated rat parotid membranes
Authors: Nadler E. , Nijjar M.S. , Oron Y.
Published: July 2002

Parotid gland membranes labelled with [3H]inositol were challenged with the cholinergic agonist, carbamylcholine, or with epinephrine in the presence of propranolol. Both agonists caused a significant breakdown of labelled phosphoinositides (17.5%) in membranes suspended in Krebs‐Ringer bicarbonate buffer. This effect was abolished by the respective antagonists, atropine or phentolamine. The carbamylcholine‐induced breakdown of labelled phosphoinositides did not require cytosol. The addition of cytosol alone, or the exposure of membranes to a medium of low ionic strength caused a significant breakdown of phosphoinositides (10–40%). No further breakdown due to the addition of carbamylcholine was observed under these conditions. It is suggested that neurotransmitter‐induced breakdown of phosphoinositides is effected by membrane‐associated enzyme(s) and can be observed only in a medium of high ionic strength.
Evidence from peptide mapping for a human renin zymogen
Authors: McIntyre Gordon D. , Chaudhuri Subhendu , Coggins John R.
Published: July 2002

Data obtained from peptide mapping of the active and inactive forms of human renin show that there are extensive regions of common sequence in the two forms of the enzyme, and are consistent with the hypothesis that inactive renin is a renin zymogen.
Primary culture, cellular stress and differentiated function
Authors: Wolffe Alan P. , Tata Jamshed R.
Published: July 2002

Isolation of specialized cell types for the analysis of tissue‐specific gene function often results in loss of the differentiated phenotype. Examples of this type of phenotypic change following tissue disaggregation are reviewed together with possible explanations. Close similarities between the effects of cell isolation with those of other cellular stresses such as heat or anoxia point to common biochemical mechanisms being involved. This suggests that the study of freshly isolated cells will contribute significantly to out understanding of the nature of cellular stress and its consequences for the maintenance of phenotype and induction of tissue specific gene expression.
Xanthine oxidase induced depolymerization of hyaluronic acid in the presence of ferritin
Authors: Carlin Gunnar , Djursater Richard
Published: July 2002

Oxygen free radicals generated by xanthine oxidase are able to depolymerize hyaluronic acid in the presence of ferritin‐bound iron. This suggests that ferritin can catalyse the Haber‐Weiss reaction, leading to the formation of highly damaging hydroxyl radicals.
Evidence for the presence of tropomyosin in the cytoskeletons of ADP‐ and thrombin‐stimulated blood platelets
Authors: Pho D.B. , Vasseur C. , Desbruyeres E. , Olomucki A.
Published: July 2002

Stimulation of porcine platelets with ADP or thrombin and subsequent analyses of their cytoskeletons by SDS‐polyacrylamide gel electrophoresis have shown the presence of a 30.5‐kDa polypeptide in the cytoskeletons of activated as well as aggregated platelets. This polypeptide comigrates with pure porcine platelet tropomyosin in SDS gels, their mobilities being similarly and markedly decreased in the presence of 6 M urea. One‐dimensional peptide mapping after limited proteolysis by Staphylococcus aureus protease gives the same pattern for pure tropomyosin and the 30.5‐kDa polypeptide. This latter may thus be identified as the porcine platelet tropomyosin subunit, the role of which may not be solely structural.
Calmodulin may mediate 1,25‐dihydroxyvitamin D‐stimulated intestinal calcium transport
Authors: Bikle Daniel D , Munson Scott , Chafouleas James
Published: July 2002

1,25‐Dihydroxyvitamin D (1,25(OH)2D) stimulated an increase in calmodulin content in chick duodenal brush border membranes in parallel with an increase in duodenal calcium transport in vivo and calcium uptake by brush border membrane vesicles (BBMV) in vitro. The increase in calcium uptake by BBMV was blocked by specific calmodulin antagonists. These results suggest that calmodulin mediates 1,25(OH)2D‐stimulated calcium movement across the brush border membrane.
A specific translocator for oxaloacetate transport in chloroplasts
Authors: Hatch M.D. , Dröscher L. , Flügge U.I. , Heldt H.W.
Published: July 2002

Evidence is provided that oxaloacetate is taken up by chloroplasts from maize and spinach leaves by a high‐affinity carrier. Apparent K
m values for oxaloacetate are about 45 and 9 μM, respectively. Uptake was measured by following [4‐14C]oxaloacetate reduction in illuminated chloroplasts. With maize chloroplasts the rates of uptake were sufficient to account for photosynthesis. This carrier had a very low affinity for malate and 2‐oxoglutarate. Ratios of the K
i, for malate or 2‐oxoglutarate to the K
m for oxaloacetate were about 150 and 50, respectively.
The calmodulin fraction responsible for contraction in an intestinal smooth muscle
Authors: Rüegg J.C. , Pfitzer G. , Zimmer M. , Hofmann F.
Published: July 2002

Freeze‐dried fibers of smooth muscle from Taenia coli were used to determine the concentration of calmodulin responsible for contraction. About 10% of the total intracellular calmodulin (12.6 μmol/kg wet wt) is directly involved in initiation of smooth muscle contraction.
Effect of polyethylene glycol on the kinetic behaviour of pyruvate kinase and other potentially regulatory liver enzymes
Authors: Medina Ruth , Aragón Juan J. , Sols Alberto
Published: July 2002

Assay in the presence of 10% polyethylene glycol has been systematically used with potentially regulatory liver enzymes as an indirect way to induce aggregation of enzymes corresponding to that which could occur at their physiological concentrations. Pyruvate kinase L was markedly affected by polyethylene glycol, as was muscle phosphorylase a, while pyruvate kinase M as well as glucokinase, fructose‐1,6‐bisphosphatase and other liver enzymes examined were not affected.
GTP enhances inositol trisphosphate‐stimulated Ca2+ release from rat liver microsomes
Authors: Dawson A.P.
Published: July 2002

Low concentrations of GTP (10–50 μM) greatly enhance the inositol 1,4,5‐trisphosphate stimulated Ca2+ release from rat liver microsomal vesicles. The effect of GTP depends on the presence of low concentrations of polyethylene glycol in the incubation medium. Guanylyl imidodiphosphate is ineffective at mimicking the GTP effect and inhibits the action of GTP added subsequently.
Light‐driven uptake of pyruvate into mesophyll chloroplasts from maize
Authors: Flügge Ulflngo , Stitt Mark , Heldt Hans Walter
Published: July 2002

(i) Photosynthesis in maize, a C4 species, involves a movement of pyruvate from the bundle sheath to the mesophyll, which has been suggested to occur by symplastic diffusion. (ii) Measurement ofmetabolite distribution in maize leaves revealed that the bulk of the pyruvate in the mesophyll was not in diffusion equilibrium with pyruvate in the bundle sheath, indicating that most of the mesophyll pyruvate was not located in the cytosol but accummulated in a subcellular compartment. (iii) In concurrence with these results, transport measurements revealed a light‐dependent active transport of pyruvate into maize mesophyll chloroplasts, probably driven by a proton gradient. This active transport of pyruvate may be regarded as an important factor in driving a malate‐pyruvate shuttle in C4 photosynthesis.
Agents that elevate platelet cAMP stimulate the formation of phosphatidylinositol 4‐phosphate in intact human platelets
Authors: de Chaffoy de Courcelles D. , Roevens P. , van Belle H.
Published: July 2002

The present study investigates the effect of compounds that are known to elevate cAMP on the phospholipid metabolism of platelets. Prostaglandin E1, forskolin and isobutylmethylxanthine induce an increase in [32P]‐phosphatidylinositol 4‐phosphate (PIP) in platelets prelabelled with [32P]orthophosphate. Possible roles of this phenomenon are discussed in view of the inhibitory effect of cAMP elevation on platelet activation.
Effect of the integrity of the myofibrillar structure on the tryptic accessibility of a hinge region of the myosin rod
Authors: Assulin Olga , Werber Moshe M. , Muhlrad Andras
Published: July 2002

Limited proteolysis has been used to study the influence of actin, in the absence or presence of regulatory proteins of the thin filament (tropomyosin and troponin), as well as that of the myofibrillar structure on the tryptic cleavage of the heavy meromyosin (HMM)/light meromyosin (LMM) hinge region in myosin heavy chain. Cleavage at the HMM/LMM hinge is almost absent in myofibrils, whereas this hinge is accessible to tryptic digestion in actomyosin, in native thin filaments attached to myosin and in myosin heavy chain alone. This observation indicates that it is the myofibrillar structure which profoundly affects the tryptic accessibility of this specific hinge region of myosin. This provides a good example of the manner by which a highly organized supramolecular structure might affect the chemical properties of a specific site in a macromolecule.
Light‐induced Fourier transform infrared (FTIR) spectroscopic investigations of primary reactions in photosystem I and photosystem II
Authors: Tavitian B.A. , Nabedryk E. , Mäntele W. , Breton J.
Published: July 2002

Light‐induced Fourier transform infrared (FTIR) difference spectroscopy has been applied for the first time to primary reactions in green plant photosynthesis. Photooxidation of the primary electron donor (P700) in photosystem I‐enriched particles as well as in thylakoids, and photoreduction of the pheophytin (Pheo) intermediary electron acceptor in photosystem II‐enriched particles, have led to reproducible difference spectra. In the spectral range investigated (between 1800 and 1000 cm−1) several bands are tentatively attributed to changes in intensity and position of the keto and ester carbonyl vibrations of the chlorophyll or Pheo molecule(s) involved. For some of these groups, possible interpretations in terms of changes of their environment or type of bonding to the protein are given. The intensity of the differential features in the amide I and amide II spectral region allows the exclusion of the eventuality of large protein conformational changes occurring upon primary charge separation.
Avidin as a probe of the conformational changes induced in pyruvate carboxylase by acetyl‐CoA and pyruvate
Authors: Attwood Paul V. , Mayer Frank , Wallace John C.
Published: July 2002

Sheep liver pyruvate carboxylase was mixed with avidin at a molar ratio of 1:1 in the presence of various combinations of the components of the assay systems required for either the acetyl‐CoA‐dependent or the acetyl‐CoA‐independent activity and negatively stained samples were examined by electron microscopy. Significant numbers of chain‐like polymers of enzyme‐avidin complexes were evident only when acetyl‐CoA or high levels of pyruvate were present in the media. Similar results were also obtained for chicken liver pyruvate carboxylase despite this enzyme's almost complete lack of acetyl‐CoA‐independent activity. Thus, although acetyl‐CoA and high concentrations of pyruvate may induce pyruvate carboxylase to adopt a ‘tight’ tetrahedron‐like conformation which can interact with avidin to form chains, this structural change alone does not result in an enzymic form that is maximally active. This suggests that the allosteric activation of pyruvate carboxylase by acetyl‐CoA is attributable, at least in part to more subtle conformational changes, especially in the case of the chicken enzyme.
Ferritin, a physiological iron donor for microsomal lipid peroxidation
Authors: Koster J.F. , Slee R.G.
Published: July 2002

In the process of lipid peroxidation of microsomes induced either by oxygen radicals generated by xanthine oxidase or by NADPH, ferritin is able to donate the necessary iron. The amount of ferritin necessary to catalyze the process of lipid peroxidation is in the physiological range. In contrast to the finding with phospholipid liposomes, catalase hardly stimulates the lipid peroxidation of microsomes.
The catalytic mechanism of aspartic proteinases
Authors: Pearl Laurence H.
Published: July 2002

The highly symmetric active site of an aspartic proteinase, endothiapepsin, binds a water molecule ideally situated for nucleophilic attack on a substrate peptide bond whose distortion from planarity is stabilised by interactions of the substrate with the extended binding cleft. The apparent electrophilicity of the catalysis results from this distortion. The scissile peptide bond is orientated with the carbonyl oxygen hydrogen bonding to the tip of the β‐hairpin ‘flap’ which lies over the cleft. Nucleophilic attack by the bound water leads to a tetrahedral intermediate similar to observed complexes with hydroxyl inhibitors and stabilised by hydrogen bonds with the flap.
The common structure and activities of four subspecies of rat brain protein kinase C family
Authors: Kikkawa Ushio , Ogita Kouji , Ono Yoshitaka , Asaoka Yoshinori , Shearman Mark S. , Fujii Tomoko , Ase Katsuhiko , Sekiguchi Kazuo , Igarashi Koichi , Nishizuka Yasutomi
Published: July 2002

Elucidation of the complete sequences of four cDNA clones (α, βI, βII, and γ) of the rat brain protein kinase C family has revealed their common structure composed of a single polypeptide chain with four constant (C1‐C4) and five variable (V1‐V5) regions. Although these sequences are highly homologous and closely related to one another V3‐, V4‐, and V5‐regions of γ‐subspecies are slightly bigger than the corresponding regions of the other three subspecies. The first constant region, C1, contains a tandem repeat of cysteine‐rich sequence (6, total 12 cysteine residues). The third constant region, C3, has an ATP‐binding sequence which is found in many protein kinases. In adult rat whole brain, the relative activities of α‐, βI, βII, and γ‐subspecies are roughly 16, 8, 55, and 21%, respectively. γ‐Subspecies is expressed after birth apparently only in the central nervous tissue, implying its role in the regulation of specific neuronal functions.
Synthetic diacylglycerols induce a rise of quin2‐detectable free intracellular calcium in human platelets
Authors: Bruns Christian , Schächtele Christoph , Marmé Dieter
Published: July 2002

The two activators of protein kinase C, oleoylacetylglycerol (OAG) and dioctanoylglycerol (DOG), are able to induce a concentration‐dependent rise in cytoplasmic free Ca2+ concentration in gel‐filtered human platelets, detected as an increase in quin2 fluorescence. The phorbol ester phorbol‐12‐myristate‐13‐acetate (PMA) has no effect. The OAG‐induced increase of intracellular Ca2+ is not influenced by forskolin, in contrast to the effect of the diterpene on the thrombin‐stimulated increase in cytoplasmic Ca2+. It is concluded that the increase in intracellular free Ca2+ concentration induced by synthetic diacylglycerols and their activation of protein kinase C are two different and independent processes.
Highly potent and specific inhibitors of human renin
Authors: Sham Hing L. , Stein Herman , Rempel Cheryl A. , Cohen Jerome , Plattner Jacob J.
Published: July 2002

We have designed and synthesized a series of small peptides containing a perfluoroalkyl ketone group at the C‐terminal position of the angiotensin I sequence as inhibitors of human renin. From this series of compounds, 8 and 10 showed strong inhibition of human renin (IC50 = 3 × 10−9, 7 × 10−9 M, respectively). Compound 10 did not inhibit pepsin and cathepsin D at 10−4 M. Comparison of the IC50 of compound 8 and compound 11 (8.7 × 10−7 M) demonstrated the marked effect of the perfluoropropyl group on the potency of inhibition on renin, presumably due to the strong electron‐withdrawing effect causing the ketone in 8 to exist predominantly as the hydrate — thus mimicking the tetrahedral transition state during hydrolysis of the scissile Leu10—Val11 amide bond.
Distinct functions of down‐regulation‐sensitive and ‐resistant types of protein kinase C in rabbit aortic smooth muscle cells
Authors: Kariya Ken-ichi , Takai Yoshimi
Published: July 2002

In quiescent cultures of rabbit aortic smooth muscle cells, 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) induced DNA synthesis to some extent in the presence of rabbit plasma‐derived serum but inhibited the rabbit whole blood serum (WBS)‐induced DNA synthesis and increase in cytoplasmic free Ca2+ concentration ([Ca2+]i). Prolonged treatment of the cells with phorbol‐12,13‐dibutyrate (PDBu) caused the partial down‐regulation of protein kinase C to a level of 25–35% of that in control cells. In these PDBu‐pretreated cells, TPA neither induced DNA synthesis nor inhibited the WBS‐induced DNA synthesis, but still inhibited the WBS‐induced increase in [Ca2+]i. These results suggest (i) that there are down‐regulation‐sensitive and ‐resistant types of protein kinase C in rabbit aortic smooth muscle cells; (ii) that the down‐regulation‐sensitive type has the proliferative and antiproliferative actions whereas the down‐regulation‐resistant type lacks them; and (iii) that the down‐regulation‐resistant type has the activity to inhibit the WBS‐induced increase in [Ca2+]i.
Plasmalogen content and distribution in the sarcolemma of cultured neonatal rat myocytes
Authors: Post J.A. , Verkleij A.J. , Roelofsen B. , de Kamp J.A.F.Op
Published: July 2002

Phospholipids are believed to play an important role in pathology and physiology of the myocardium. Because of the distinct physico‐chemical properties of plasmalogens we studied the plasmalogen content and distribution in the sarcolemma of cultured rat myocytes. Treatment with phospholipase A2 degraded all glycerophospholipids in the outer monolayer. The hydrolysis products were analyzed for plasmalogen content. It is shown that the inner sarcolemmal leaflet is highly enriched in phosphatidylcholine and ethanolamine plasmalogen. This distribution of the plasmalogens might affect bilayer stability and thereby be involved in the destruction of the sarcolemma upon ischemia and reperfusion.
Identification of [hydroxyproline3]‐lysyl‐bradykinin released from human kininogens by human urinary kallikrein
Authors: Maier Manfred , Reissert Guenther , Jerabek Ingrid , Lottspeich F. , Binder Bernd R.
Published: July 2002

The types of kinins released from purified native, single chain human high and low molecular mass kininogens (HMMKs and LMMKS, respectively) by purified human urinary kallikrein were separated by reverse‐phase HPLC and quantitated by the rat uterus bioassay. [Hyp3]‐ysyl‐bradykinin, a recently discovered kinin, represented up to 58% of the biological activity released from 4 individual HMMK preparations purified from 4 different healthy volunteers. In contrast, the majority of the biological activity released from LMMKs purified from pooled plasma was identified as Lys‐bradykinin and [Hyp3]‐lysyl‐bradykinin represented only 6.4 ± 3.8%. These findings indicate posttranslational hydroxylation of human kininogens and suggest a preference of HMMKs for this modification.
(Ca2+ + Mg2+)‐dependent ATPase mRNA from smooth muscle sarcoplasmic reticulum differs from that in cardiac and fast skeletal muscles
Authors: de la Bastie Diane , Wisnewsky Claudine , Schwartz Ketty , Lompré Anne-Marie
Published: July 2002

We have investigated some characteristics of the sarcoplasmic reticulum (Ca2+ + Mg2+)‐dependent ATPase (Ca2+‐ATPase) mRNA from smooth muscle using specific cDNA probes isolated from a rat heart cDNA library. RNA blot analysis has shown that the Ca2+‐ATPase mRNA expressed in smooth muscle is identical in size to the cardiac mRNA but differs from that of fast skeletal muscle. S1 nuclease mapping has moreover shown that the cardiac and smooth muscle isoforms possess different 3′‐end sequences. These results indicate that a distinct sarcoplasmic reticulum Ca2+‐ATPase mRNA is present in smooth muscle.
The effect of inhibition of cholesterol esterification on the fate of cholesterol derived from HDL in rat hepatocyte monolayers
Authors: Sampson William J. , Botham Kathleen M. , Jackson Brian , Suckling Keith E.
Published: July 2002

Rat HDL2 is known to stimulate bile acid synthesis in rat hepatocyte monolayers. The intracellular fate of the cholesterol derived from the HDL2 was studied using the inhibitor of cholesterol esterification, Sandoz compound 58‐035. Rat HDL2 added to rat hepatocyte monolayers caused a stimulation of cholesterol esterification of 32%. This stimulation could be inhibited by 58‐035. A small significant increase in bile acid synthesis was also observed in cells in the presence of HDL2, confirming our earlier observations. 58‐035 prevented this increase. These observations imply that cholesterol entering the cell from HDL2 is first esterified and can only enter the substrate pool for bile acid synthesis after subsequent intracellular hydrolysis.
Endogenous inhibitor of the ADP‐ribosylation of (a) G‐protein(s) as catalyzed by pertussis toxin is present in rat liver
Authors: Hara-Yokoyama Miki , Furuyama Shunsuke
Published: July 2002

The inhibitor activity of the ADP‐ribosylation of (a) G‐protein(s) as catalyzed by pertussis toxin was found in the membrane extract of rat liver. The inhibitor activity was found in the fractions of DEAE‐Sephacel column chromatography at 50–120 mM NaCl. The inhibitor activity is not due to the degradation of NAD nor to the reverse reaction of pertussis toxin (removal of incorporated ADP‐ribose). The present result suggests the presence of an endogenous inhibitor of the ADP‐ribosylation reaction of (a) G‐protein(s).
Regulation of the β2‐adrenergic receptor and its mRNA in the rat ventral prostate by testosterone
Authors: Collins Sheila , Quarmby Valerie E. , French Frank S. , Lefkowitz Robert J. , Caron Marc G.
Published: July 2002

To investigate the regulation of β2AR expression in rat ventral prostate the effects of castration and testosterone replacement on the β2AR were studied by ligand binding and Northern blot analysis. Orchidectomy depressed β2AR number by 50% within 4 days and testosterone administration to 4‐day castrates produced a rapid and complete recovery of β2AR number within 24 h. In contrast to receptor number, β2AR mRNA levels did not change relative to total RNA following castration. However, during the testosterone replacement period β2AR mRNA levels rose transiently, reaching a maximum (3.5‐fold) between 8 and 12 h, and this increase in mRNA preceded the recovery in β2AR number in the membrane. Regulation of β2AR gene expression by testosterone in the ventral prostate is thus complex and probably involves both transcriptional and post‐transcriptional components.
Cyclic AMP inhibits mitogen‐induced DNA synthesis in hamster fibroblasts, regardless of the signalling pathway involved
Authors: Magnaldo Isabelle , Pouysségur Jacques , Paris Sonia
Published: July 2002

Mitogen‐induced initiation of DNA synthesis in quiescent Chinese hamster lung fibroblasts (CCL39) is strongly inhibited by 8‐Br cAMP and cAMP‐elevating agents (prostaglandin E1, cholera toxin, isobutylmethylxanthine). This inhibition is reversible and occurs very early in G0/G1. As exponential growth is much less affected by increased cAMP, we propose that cAMP inhibits an early signal essential for the exit from G0. CCL39 cells can be stimulated by α‐thrombin, which activates phosphoinositide (PI) ]breakdown, as well as by mitogens (FGF or FGF+serotonin) which do not involve the PI pathway. Here we show that the action of both classes of mitogens is likewise inhibited by cAMP. Therefore, although PI breakdown is inhibited by cAMP in CCL39 cells, this effect cannot entirely account for the antimitogenic activity of cAMP. Other early steps of the mitogenic response must be also affected.
Down‐regulation of fast‐twitch skeletal muscle fiber with cardiac troponin‐C and recombinant mutants Structure/function studies with site‐directed mutagenesis
Authors: Gulati Jagdish , Babu Árvind , Putkey John A.
Published: July 2002

Structure/function relationships in troponin C are studied with vertebrate fast‐twitch fibers by exchanging the skeletal troponin C with two bacterially synthesized recombinant proteins designed by site‐directed mutagenesis of cardiac troponin C. One mutant (CBM1) contained an additional active site, by deleting Val‐28 and converting Leu‐29, Gly‐30, Ala‐31 and Glu‐32 to Asp, Ala, Asp and Gly, respectively, in the normally inactive trigger site 1 in the N‐terminus. In another mutant (CBM2A), the normally active site 2 was inactivated by conversion of Asp‐65 to Ala. The fibers were found to be down‐regulated with recombinant cardiac troponin C (CTnC3), as with tissue‐cardiac‐troponin‐C. With mutants, in one case (CBM1) the regulation was unmodified despite Ca2+ coordination by all sites. In contrast, regulation was found to be completely blocked with the mutant (CBM2A) where both trigger sites were inactive. The results provide the first indication that structural specification of the entire EF‐hand motif of site 1, and not just Ca2+ coordination, is needed to operate fully the Ca2+ switch in fast‐twitch fibers.
Kinetic β‐deuterium isotope effects suggest a covalent mechanism for the protein folding enzyme peptidylprolyl cis/trans‐isomerase
Authors: Fischer Gunter , Berger Edith , Bang Holger
Published: July 2002

The cis/trans interconversion of Glt‐Ala‐Ala‐Pro‐Phe‐4‐nitroanilide and Glt‐Ala‐Gly‐Pro‐Phe‐4‐nitroanilide was studied both enzymatically and nonenzymatically by measuring kinetic β‐deuterium isotope effects. The hydrogen atom at the α‐carbon atom of the Xaa residue within the Xaa‐Pro moiety was substituted by deuterium. In the nonenzymatic case the transition state of rotation is reflected by k
H/k
D > 1. When catalysed by 17 kDa PPIase the same bond rotation is characterized by k
H/k
D < 1. This suggests a covalent mechanism of catalysis which involves an approximately tetravalent carbon of the prolyl imidic bond for the transition state of reaction.
Angiotensinogen production by rat hepatoma cells is stimulated by B cell stimulatory factor 2/interleukin‐6
Authors: Itoh Norio , Matsuda Toshie , Ohtani Remiko , Okamoto Hiroshi
Published: July 2002

Angiotensinogen has been identified as one of the acute‐phase reactants. In vitro studies were carried out using the Reuber H35 hepatoma cell line to identify the species of cytokines contributing to the increased synthesis of angiotensinogen in the liver. Angiotensinogen secretion by H35 cells was maximally increased 4‐fold by the addition of 10−7 M dexamethasone. Under this condition, angiotensinogen secretion was further stimulated by B cell stimulatory factor 2/interleukin‐6 (IL‐6, 50 U/ml), but not by interleukin‐1 or interferon‐α. In the absence of glucocorticoid, IL‐6 did not affect angiotensinogen secretion by H35 cells, indicating that the presence of glucocorticoid is required for the stimulatory activity of IL‐6. These suggest that IL‐6 is a mediator responsible for the increased synthesis of angiotensinogen in the liver during acute inflammation.
Protein synthesis in rat cardiac myocytes is stimulated at the level of translation by phorbol esters
Authors: Fuller Stephen J. , Sugden Peter H.
Published: July 2002

12‐O‐Tetradecanoylphorbol 13‐acetate acutely stimulated the rate of protein synthesis maximally by about 43% in terminally differentiated myocytes freshly isolated from adult rat hearts. Stimulation was rapidly expressed (within 20 min). The relative effects of four phorbol esters on protein synthesis was consistent with a specific effect on protein kinase C. Inhibition of transcription with actinomycin D had no effect on the absolute stimulation of the protein synthesis rate by 12‐O‐tetradecanoylphorbol 13‐acetate. We conclude that protein kinase C may be involved in the regulation of the translational process.
The cDNA of the two isoforms of bovine cGMP‐dependent protein kinase
Authors: Wernet W. , Flockerzi V. , Hofmann F.
Published: July 2002

cDNAs encoding the isoform Iα of the cGMP‐dependent protein kinase were isolated from a bovine trachea smooth muscle cDNA library constructed in λgt10. The deduced protein sequence is identical with the protein sequence obtained by Edman degradation of the bovine lung enzyme [(1984) Biochemistry 23, 4207–4218]. Alternate cDNA clones were isolated which code for a protein slightly different within the aminoterminal part from the known amino acid sequence. These alternate cDNAs contain the sequence of a peptide identified in the isoform 1β of cGMP‐dependent protein kinase. Northern blot analysis of poly(A)+ RNA from bovine trachea smooth muscle indicated the presence of two different mRNA species of about 6.2 kb.