bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of hypocholesterolaemic agents on the expression and activity of 3‐hydroxy‐3‐methylglutaryl‐CoA reductase in the fat body of the German cockroach
Authors: Zapata Rafael , Martín David , Piulachs Maria‐Dolors , Bellés Xavier 
Published: August 2002

AbstractIn the fat body of adult Blattella germanica females, the expression of 3‐hydroxy‐3‐methylglutaryl‐CoA reductase (HMG‐CoA reductase) during the first reproductive cycle is parallel to that of vitellogenin, suggesting a functional link between the mevalonate pathway, and vitellogenesis and reproduction. We have studied the effects of compactin and fluvastatin, two inhibitors of HMG‐CoA reductase, on the expression and activity of the enzyme in the fat body, and on the ootheca formation, ootheca viability, and number of larvae per viable ootheca. Short‐term assays showed that both compounds reduce the protein levels and enzymatic activity of HMG‐CoA reductase, and long‐term experiments revealed that fluvastatin impairs embryo development. Arch. Insect Biochem. Physiol. 49:177–186, 2002. © 2002 Wiley‐Liss, Inc.
Hydrogen peroxide detoxification in the midgut of the blood‐sucking insect, Rhodnius prolixus
Authors: Paes Marcia Cristina , Oliveira Mariana Borges , Oliveira Pedro L. 
Published: August 2002

AbstractHere we investigated H2O2 production and detoxification in the hematophagous hemiptera, Rhodnius prolixus. Superoxide dismutase (SOD) catalyzes the dismutation of superoxide radical (O2–). This reaction produces hydrogen peroxide, which is scavenged by antioxidant enzymes such as catalase (CAT). SOD and CAT activities were found in all tissues studied, being highest in the midgut. CAT was dose‐dependently inhibited in vivo by injections of 3‐amino‐1,2,4‐triazole (AT). Insects treated with AT showed a twofold increase in H2O2 levels. Injection of DL‐buthionine‐[S, R]‐sulfoximine (BSO), an inhibitor of glutathione synthesis, also resulted in a fourfold increase in H2O2, together with stimulation of CAT activity. Simultaneous administration of both AT and BSO had a synergistic effect on midgut H2O2 content. Taken all together, our results suggest that CAT and glutathione‐dependent mechanisms cooperate to control H2O2 concentration in the midgut cell and prevent hydroxyl radical generation by Fenton reaction in this tissue. Arch. Insect Biochem. Physiol. 48:63–71, 2001. © 2001 Wiley‐Liss, Inc.
Developmental variation in cytochrome P450 expression in Papilio polyxenes in response to xanthotoxin, a hostplant allelochemical
Authors: Harrison Terry L. , Zangerl Arthur R. , Schuler Mary A. , Berenbaum May R. 
Published: August 2002

AbstractAlthough developmental variation in activity and inducibility is typical of cytochrome P450 monooxygenases (P450s) in insects, the adaptive significance of such variation is often unclear, in part because the natural function of insect P450s is rarely known. In this study, we examined developmental variation in expression of CYP6B1 and CYP6B3 in Papilio polyxenes, the black swallowtail. Enzymes encoded by these genes have been implicated in the metabolism of xanthotoxin, a furanocoumarin characteristic of the apiaceous hostplants of P. polyxenes. In each life stage—egg, five larval instars, pupa, and adult—we examined individuals exposed to foliage with and without supplemental xanthotoxin. For each stage, we conducted enzyme assays to estimate xanthotoxin metabolism, Northern analysis to detect constitutive and induced mRNA levels, and RT‐PCR amplification and Southern analysis to differentiate among P450 genes expressed. Inducible xanthotoxin metabolism, previously reported in fifth instars, was observed in four of five larval stages but was absent or undetectable in all stages that do not feed on foliage; the highest levels of activity were in early larval instars. The same pattern was observed in both Northern and RT‐PCR gel blot analyses. In inducible larval stages, inducibility of CYP6B1 transcripts by xanthotoxin was greater than the inducibility of CYP6B3 transcripts. These findings support earlier suggestions that these two P450s contribute to xanthotoxin metabolism in this species and that expression of these P450 genes is regulated in an adaptive fashion with respect to probability of exposure to hostplant toxins over the course of development. Arch. Insect Biochem. Physiol. 48:179–189, 2001. © 2001 Wiley‐Liss, Inc.
The role of biomechanical factors and HLA‐B27 in magnetic resonance imaging‐determined bone changes in plantar fascia enthesopathy
Authors: McGonagle Dennis , Marzo‐Ortega Helena , O'Connor Philip , Gibbon Wayne , Pease Colin , Reece Richard , Emery Paul 
Published: August 2002

AbstractObjectiveTo study the role of biomechanical factors and HLA‐B27 in plantar fasciitis.MethodsT1‐weighted and T2 spectral presaturation with inversion recovery (fat suppressed) magnetic resonance imaging (MRI) sequences of the plantar fascia insertion and adjacent bone were performed on 28 patients with plantar fasciitis; 17 had spondylarthropathy (SpA)‐associated disease, and 11 had mechanically induced disease. The relationship between the degree of bone edema, scored on a semiquantitative scale (from absent to severe), and the patient's HLA‐B27 status was determined.ResultsOn MRI, edema within the soft tissue at the enthesis was evident in both groups. Bone edema in the adjacent calcaneum was evident in 64.7% (11 of 17) of patients with SpA and in 45% (5 of 11) of those with mechanically induced disease (P = 0.441). HLA‐B27 was identified in 9 (53%) of the patients with SpA but in none (0%) of those with mechanically induced disease. All 6 of the SpA patients with extensive bone edema but none of the 5 SpA patients with mild bone edema were HLA‐B27 positive (P = 0.002).ConclusionThe association of HLA‐B27 with bone pathology in early enthesitis may have implications for a better understanding of the pathogenesis of SpA.
Intranasal absorption of sumatriptan and naratriptan: no evidence of local transfer from the nasal cavities to the brain arterial blood in male rats
Authors: Einer‐Jensen Niels , Larsen Lise , Deprez Stephanie , Starns Elaine , Schwartz Sheila 
Published: August 2002

AbstractNasal administration to rats of small molecules (tritiated water, tyrosine, and propanol) results in a higher concentration in the brain arterial blood than in other arteries. The preferential distribution is based on a counter current transfer, which takes place between nasal vein blood and brain arterial blood in the cavernous sinus‐carotid artery complex. This model was used to investigate whether the antimigraine 5HT1B/1D receptor agonists sumatriptan and naratriptan may also be transferred by the system. The ratio of ‘head’:‘heart’ plasma concentrations obtained from two carotid catheters after intranasal administration was not different from 1.00 for either compound, and thus, there was no experimental evidence of a preferential local transfer of drug from the nose to the carotid artery circulation. However, plasma concentrations increased from the first minute after intranasal dosing suggesting that sumatriptan and naratriptan are absorbed into the general systemic circulation from the nasal cavity in rats in a first‐order fashion with no lag time. This is consistent with the clinical onset of efficacy of sumatriptan after an intranasal dose which occurs as early as 15 min post dose. Copyright © 2001 John Wiley & Sons, Ltd.
The effect of enzyme inhibitor and absorption site following [D‐ala2, D‐leu5]enkephalin oral administration in rats
Authors: Lee Hye J. , Amidon Gordon L. 
Published: August 2002

AbstractThe effects of enzyme inhibitor, amastatin, and absorption site following intravenous (i.v.) oral (p.o.), jejunal and ileal administration of [D‐ala2, D‐leu5]enkephalin (YdAGFdL) were investigated in rats. Model dependent and independent pharmacokinetic parameters were obtained and compared. Linear pharmacokinetics of YdAGFdL were evaluated at 0.28 and 500 µg doses for i.v. and at 1, 500, and 1000 µg for p.o. and ileal routes. Plasma samples were collected and assayed for intact YdAGFdL using a radiometric thin layer chromatography. The clearance (CL) and half lives of the distribution and elimination phases following the 0.28 µg (n=6) i.v. dose were 42.7±26.2 (S.D.) ml/min, 0.48±0.17 min, and 3.98±0.92 min, while those of the 500 µg dose (n=6) were 48.0±23.3 ml/min, 0.59±0.25, and 6.81±3.12 min, respectively, suggesting apparent linear kinetics. The CL values were close to the cardiac output of rats (50 ml/min) indicating very rapid elimination from the body. Mean bioavailability (F) values following p.o. (n=15), jejunal (n=4), and ileal (n=16) administration were 0.40±0.24% (S.E.), 1.25±0.39, and 1.78±0.40, respectively, and were not significantly different (p<0.05) among three doses (1, 1000, 5000 µg). The F value of YdAGFdL following ileal administration in the presence of amastatin was 8.76±4.47% (n=6), a 22 fold increase over po administration and a five fold increase over ileal administration without an inhibitor. These results indicate that ‘effective’ oral delivery of small peptides may be achievable. Copyright © 2002 John Wiley & Sons, Ltd.
Study of thermal effects of ultrasound stimulation on fracture healing
Authors: Chang Walter Hong‐Shong , Sun Jui‐Sheng , Chang Su‐Pei , Lin James C. 
Published: August 2002

AbstractLow intensity ultrasound stimulation has been used as a strategy to promote fracture healing. This study investigated the mechanism of ultrasound stimulation in enhancing fracture healing. Forty‐five adult New Zealand White rabbits were divided into control, microwave treated, and ultrasound stimulation groups. After anesthesia, transverse osteotomy was created at midportion of the fibula bone. Intravital staining followed by fluorescence microscopic examination of new bone formation in the osteotomy site and biomechanical tests on torsional stiffness of the osteotomy site were performed. The difference between each examination was evaluated and analyzed. After ultrasound stimulation, new bone formation in the osteotomy site of the stimulated limb was 23.1–35.8% faster than that of the sham treated limb; the torsional stiffness of the stimulated limb was 44.4–80.0% higher than that of the sham treated limb. In the group of microwave hyperthermia treatment, the new bone formation was higher than that of the sham treated limb, but the difference was not statistically significant. The difference in torsional stiffness between the microwave hyperthermia treated limbs and the sham treated limb was not quite statistically significant. We demonstrated that low intensity ultrasound stimulation could increase the new bone formation and torsional stiffness. These effects probably are not mediated via hyperthermia. Bioelectromagnetics 23:256–263, 2002. © 2002 Wiley‐Liss, Inc.
Human electrophysiological and cognitive effects of exposure to ELF magnetic and ELF modulated RF and microwave fields: A review of recent studies
Authors: Cook C.M. , Thomas A.W. , Prato F.S. 
Published: August 2002

AbstractThe investigation of weak (<500 μT), extremely low frequency (ELF, 0–300 Hz) magnetic field (MF) exposure upon human cognition and electrophysiology has yielded incomplete and contradictory evidence that MFs interact with human biology. This may be due to the small number of studies undertaken examining ELF MF effects upon the human electroencephalogram (EEG), and the associated analysis of evoked related potentials (ERPs). Relatively few studies have examined how MF exposure may affect cognitive and perceptual processing in human subjects. The introduction of this review considers some of the recent studies of ELF MF exposure upon the EEG, ERPs and cognitive and perceptual tasks. We also consider some of the confounding factors within current human MF studies and suggest some new strategies for further experimentation. Bioelectromagnetics 23:144–157, 2002. © 2002 Wiley‐Liss, Inc.
Chromosomal aberrations in peripheral lymphocytes of train engine drivers
Authors: Nordenson Ingrid , Mild Kjell Hansson , Järventaus Hilkka , Hirvonen Ari , Sandström Monica , Wilén Jonna , Blix Nils , Norppa Hannu 
Published: August 2002

AbstractStudies of Swedish railway employees have indicated that railroad engine drivers have an increased cancer morbidity and incidence of chronic lymphatic leukemia. The drivers are exposed to relatively high magnetic fields (MF), ranging from a few to over a hundred μT. Although the possible genotoxic potential of MF is unclear, some earlier studies have indicated that occupational exposure to MF may increase chromosome aberrations in blood lymphocytes. Since an increased level of chromosomal aberrations has been suggested to predict elevated cancer risk, we performed a cytogenetic analysis on cultured (48 h) peripheral lymphocytes of Swedish train engine drivers. A pilot study of 18 engine drivers indicated a significant difference in the frequency of cells with chromosomal aberrations (gaps included or excluded) in comparison with seven concurrent referents (train dispatchers) and a control group of 16 office workers. The engine drivers had about four times higher frequency of cells with chromosome‐type aberrations (excluding gaps) than the office workers (P < 0.01) and the dispatchers (P < 0.05). Seventy‐eight percent of the engine drivers showed at least one cell per 100 with chromosome‐type aberrations compared with 29% among the dispatchers and 31% among the office workers. In a follow‐up study, another 30 engine drivers showed an increase (P < 0.05) in the frequency of cells with chromosome‐type aberrations (gaps excluded) as compared with 30 referent policemen. Sixty percent of the engine drivers had one or more cells (per 100 cells) with chromosome‐type aberrations compared with 30% among the policemen. In conclusion, the results of the two studies support the hypothesis that exposure to MF at mean intensities of 2–15 μT can induce chromosomal damage. Bioelectromagnetics 22:306–315, 2001. © 2001 Wiley‐Liss, Inc.
Measurement of the individual exposure to 50 and 16 2/3 Hz magnetic fields within the Bavarian population
Authors: Brix J. , Wettemann H. , Scheel O. , Feiner F. , Matthes R. 
Published: August 2002

AbstractThis study investigates the individual magnetic field exposures at 16 2/3 and 50 Hz of 1952 people, selected from the Bavarian population. Personal flux density meters (“Field Watcher FW2A”) were worn by the participants for 24 h. Every second, the flux density was recorded for both frequencies and for the three spatial axes (dynamic range per axis: several nT up to 100 μT at 50 Hz, 150 μT at 16 2/3 Hz). For 50 Hz fields, the mean of the 1,952 individual means was 0.101 μT and that of the individual medians was 0.047 μT. High level exposures occurred mainly during working hours. Only 2.4% of the subjects showed individual medians higher than 0.2 μT. About 53% of all volunteers were working on the day of recording. Levels for craftsmen (n = 148; mean individual mean: 0.166 μT) were generally higher than those for office workers (n = 624; mean individual mean: 0.107 μT). Flux densities exceeding 100 μT at 50 Hz were measured in 31 persons. The total time with such extreme exposures amounts to nearly 21 min, less than 0.001% of the total time for all measurements (5.3 years). To our knowledge, this is the first exposure study where 16 2/3 Hz magnetic fields (caused by electrified railways) have additionally been monitored over 24 h. For persons living next to railway lines, the mean individual mean (0.156 μT) and mean individual median (0.102 μT) were calculated. Over all, the mean exposures are only 0.1% of the magnetic flux density limit for 50 Hz (100 μT) and about 0.05% of the limit (300 μT) for 16 2/3 Hz recommended by the International Commission on Non‐Ionizing Radiation Protection. Bioelectromagnetics 22:323–332, 2001. © 2001 Wiley‐Liss, Inc.
Intracellular effect of ultrashort electrical pulses
Authors: Schoenbach Karl H. , Beebe Stephen J. , Buescher E. Stephen 
Published: August 2002

AbstractA simple electrical model for biological cells predicts an increasing probability for electric field interactions with cell substructures of prokaryotic and eukaryotic cells when the electric pulse duration is reduced into the sub‐microsecond range. The validity of this hypothesis was verified experimentally by applying electrical pulses with electric field intensities of up to 5.3 MV/m to human eosinophils in vitro. When 3–5 pulses of 60 ns duration were applied to human eosinophils, intracellular granules were modified without permanent disruption of the plasma membrane. In spite of the extreme electrical power levels applied to the cells thermal effects could be neglected because of the ultrashort pulse duration. The intracellular effect extends conventional electroporation to cellular substructures and opens the potential for new applications in apoptosis induction, gene delivery to the nucleus, or altered cell functions, depending on the electrical pulse conditions. Bioelectromagnetics 22:440–448, 2001. © 2001 Wiley‐Liss, Inc.
Histone ubiquitination: a tagging tail unfolds?
Authors: Jason Laure J.M. , Moore Susan C. , Lewis John D. , Lindsey George , Ausió Juan 
Published: August 2002

AbstractDespite the fact that histone H2A ubiquitination affects about 10–15% of this histone in most eukaryotic cells, histone ubiquitination is among one of the less‐well‐characterized post‐translational histone modifications. Nevertheless, some important observations have been made in recent years. Whilst several enzymes had been known to ubiquitinate histones in vitro, recent studies in yeast have led to the unequivocal identification of the enzyme responsible for this post‐translational modification in this organism. A strong functional co‐relation to meiosis and spermiogenesis has also now been well documented, although its participation in other functional aspects of chromatin metabolism, such as transcription or DNA repair, still remains rather speculative and controversial. Because of its nature, histone ubiquitination represents the most bulky structural change to histones and as such it would be expected to exert an important effect on chromatin structure. Past and recent structural studies, however, indicate a surprising lack of effect of (H2A/H2B) ubiquitination on nucleosome architecture and of uH2A on chromatin folding. These results suggest that this modification may serve as a signal for recognition by functionally relevant trans‐acting factors and/or operate synergistically in conjunction with other post‐translational modifications such as for instance acetylation. BioEssays 24:166–174, 2002. © 2002 Wiley Periodicals, Inc.
A fresh look at the role of CaMKII in hippocampal synaptic plasticity and memory
Authors: Rongo Christopher 
Published: August 2002

AbstractAdvances in molecular, genetic, and cell biological techniques have allowed neuroscientists to delve into the cellular machinery of learning and memory. The calcium and calmodulin‐dependent kinase type II (CaMKII) is one of the best candidates for being a molecular component of the learning and memory machinery in the mammalian brain. It is present in abundance at synapses and its enzymatic properties and responsiveness to intracellular Ca2+ fit a model whereby Ca2+ currents activate the kinase and lead to changes in synaptic efficacy. Indeed, such plastic properties of synapses are thought to be important for memory formation. Genetic analysis of the alpha isoform of CaMKII in mice support the hypothesis that CaMKII signaling is required to initiate the formation of new spatial memories in the hippocampus. CaMKII is also required for the correct induction of long‐term potentiation (LTP) in the hippocampus, consistent with the widely held belief that LTP is a mechanism for learning and memory. Recent cell biological, genetic, and physiological analyses suggest that one of the cellular explanations for LTP and CaMKII function might be the trafficking of AMPA‐type receptors to synapses in response to neural activity. BioEssays 24:223–233, 2002. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/bies.10057
Braking the silence: How heterochromatic gene repression is stopped in its tracks
Authors: Donze David , Kamakaka Rohinton T. 
Published: August 2002

AbstractEukaryotic DNA is assembled into nucleosomes, which are further packaged into higher order chromatin structures containing many non‐histone chromosomal proteins. The details of this packaging have profound effects on gene expression and other cellular processes involving the genetic material. Heterochromatic domains of the genome are usually transcriptionally repressed, while euchromatic regions are transcriptionally competent. Current models of gene activation postulate the existence of boundary elements that either prevent inappropriate activation of genes by distal enhancers (enhancer blockers), or sequences that block the propagation of heterochromatin into euchromatic regions (barriers). While numerous boundary sequences have been identified, little is known with regard to the molecular mechanisms used to punctuate the genome. This review will focus on recent data that provide insight into the mode of action of barrier elements. BioEssays 24:344–349, 2002. ©2002 Wiley Periodicals, Inc.
Muscular dystrophies, the cytoskeleton and cell adhesion
Authors: Spence Heather J. , Chen Yun‐Ju , Winder Steven J. 
Published: August 2002

AbstractMuscular dystrophies are associated with mutations in genes encoding several classes of proteins. These range from extracellular matrix and integral membrane proteins to cytoskeletal proteins, but also include a heterogeneous group of proteins including proteases, nuclear proteins, and signalling molecules. Muscular dystrophy phenotypes have also become evident in studies on various knockout mice defective in proteins not previously considered or known to be mutated in muscular dystrophies. Some unifying themes are beginning to emerge from all of these data. This review will consider recent advances in our understanding of the molecules involved and bring together data that suggest a role for the cytoskeleton and cell adhesion in muscular dystrophies. BioEssays 24:542–552, 2002. © 2002 Wiley Periodicals, Inc.
Checking in on Cds1 (Chk2): A checkpoint kinase and tumor suppressor
Authors: McGowan Clare H. 
Published: August 2002

AbstractTogether, DNA repair and checkpoint responses ensure the integrity of the genome. Coordination of cell cycle checkpoints and DNA repair are especially important following genotoxic radiation or chemotherapy, during which unusually high loads of DNA damage are sustained. In mammalian cells, the checkpoint kinase, Cds1 (also known as Chk2) is activated by ATM in response to DNA damage. The role of Cds1 as a checkpoint kinase depends on its ability to phosphorylate cell cycle regulators such p53, Cdc25 and Brca1. A role for Cds1 in repair is suggested by the finding that it interacts with the Holliday junction resolving activity Mus81. This review focuses on the many questions generated by recent progress in understanding the function and regulation of human Cds1. BioEssays 24:502–511, 2002. © 2002 Wiley Periodicals, Inc.