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PubMed1999

Functional expression of rat thioredoxin reductase: selenocysteine insertion sequence element is essential for the active enzyme.

Mammalian thioredoxin reductase (TR) is a flavoprotein catalysing reduction of oxidized thioredoxin in an NADPH-dependent manner, and contains a selenocysteine (Sec) residue near the C-terminus. We observed that TR activity was decreased in A549 cells by the lowering of the fetal bovine serum content in the culture medium and was recovered by the addition of selenium. To study the role of Sec in TR activity, we have isolated a full-length clone of the rat TR cDNA (3.3 kb) and have expressed it in COS-1 cells in a transient-expression system. TR activities in COS-1 cells expressing rat TR were increased in accordance with supplemented sodium selenite concentrations, whereas levels of TR protein, examined by Western blotting, were not affected by sodium selenite concentrations. We introduced various deletions into the 3'-untranslated region of the TR cDNA to localize and examine the role of a Sec insertion-sequence (SECIS) element in the functional expression of TR. TR activities were observed only in COS-1 cells transfected with the TR cDNAs containing the putative SECIS element located between 1856 and 1915 bp in the correct orientation. We also carried out radiolabelling of proteins by incubation of the cDNA-transfected cells with sodium [75Se]selenite. 75Se was incorporated into the expressed TR protein of the cells transfected with the SECIS element-containing cDNAs, but not into those without the SECIS element or with an inverted SECIS element. These data clearly showed a requirement of selenium for the formation of functional TR protein.

3' Untranslated Regions↗
PubMed1990

Pregnancy-induced mobilization of copper and zinc bound to renal metallothionein in cadmium-loaded rats.

Our investigations undertook to examine whether copper (Cu) and zinc (Zn) bound to renal metallothionein (MT) along with cadmium (Cd) in Cd-loaded rats can be mobilized during pregnancy and lactation. Rats of the Wistar strain were injected with Cd. Synthesis of MT containing Cd, Cu and Zn was induced in the kidneys. Concentrations of Cd and essential elements in blood plasma and organs (liver and kidneys) were compared among non-pregnant and pregnant, and Cd-loaded and non-loaded rats at middle and late gestational days and after delivery. Cu bound to renal MT was decreased with gestational age, while Zn was slightly increased. The results indicate that Cu was mobilized and utilized even when the metal was bound to MT in the kidneys of dams. On the other hand, Zn bound to renal MT in Cd-loaded rats was retained and not mobilized during pregnancy. The elution profile of renal MT on an SW column was changed from a typical renal to a mixed profile of renal and hepatic MTs as a result of decreased Cu content in MT. Plasma essential elements changed similarly with gestational age in both concentrations and distributions in non-loaded and Cd-loaded rats. These results indicate that the 3 metals bound to renal MT are dealt with differently during gestation and lactation, and Cu but not Zn is transferred to the fetus, independently of the Cd status of the dam.

Animals↗
PubMed1998

Exposure to lead and other metals in children from Katowice district, Poland.

OBJECTIVES: To assess the exposure to toxic metals and to evaluate its possible association with essential elements and socioeconomic status in children from the town of Bytom in the Katowice area; this area is one of the most polluted industrialized regions in Poland. METHODS: Concentrations of lead, cadmium, mercury, selenium, magnesium, copper, and zinc were determined in whole blood of 211 children aged 9 years. The samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Information on socioeconomic factors was collected using questionnaires. Concentrations of trace elements in the blood of 24 Swedish children aged 9-10 years were used for comparisons. RESULTS: The concentrations of lead detected in the blood of the Polish children ranged from 0.09 to 1.9 mumol/l, with the median value being 0.27 mumol/l. Statistically significant associations were found between lead and such socioeconomic factors as the number of siblings, trips outside the region, maternal smoking, playing outdoors, and apartment standard. The average blood lead level was about 3 times higher in the Polish children than in the Swedish group. The median blood concentration of cadmium found in the Polish children was 3.4 nmol/l (range 1.1-41 nmol/l; almost 3 times higher than that detected in the Swedish children), and that of mercury was 3 nmol/l (range 0.5-11 nmol/l). The median blood levels and ranges of the essential elements were 1.1 (0.7-2.0) mumol/l for selenium, 1.5 (1.2-1.9) mmol/l for magnesium, 17 (13-22) mumol/l for copper, and 78 (54-104) mumol/l for zinc, respectively. The concentrations of selenium and magnesium were significantly lower in the Polish group as compared with the Swedish children. CONCLUSIONS: In all, 7% of the Polish children had blood lead levels exceeding 0.5 mumol/l, the concentration above which negative effects on mental development have been reported. However, the findings indicate a decrease in lead exposure during recent years among the Bytom children.

Child↗
PubMed2005

Schoenheimer effect explained--feedback regulation of cholesterol synthesis in mice mediated by Insig proteins.

End-product feedback inhibition of cholesterol synthesis was first demonstrated in living animals by Schoenheimer 72 years ago. Current studies define Insig proteins as essential elements of this feedback system in mouse liver. In cultured cells, Insig proteins are required for sterol-mediated inhibition of the processing of sterol regulatory element-binding proteins (SREBPs) to their nuclear forms. We produced mice with germline disruption of the Insig2 gene and Cre-mediated disruption of the Insig1 gene in liver. On a chow diet, these double-knockout mice overaccumulated cholesterol and triglycerides in liver. Despite this accumulation, levels of nuclear SREBPs and mRNAs for SREBP target genes in lipogenic pathways were not reduced. Whereas cholesterol feeding reduced nuclear SREBPs and lipogenic mRNAs in wild-type mice, this feedback response was severely blunted in the double-knockout mice, and synthesis of cholesterol and fatty acids was not repressed. The amount of HMG-CoA reductase protein was elevated out of proportion to the mRNA in the double-knockout mice, apparently owing to the failure of cholesterol to accelerate degradation of the enzyme. These studies indicate that the essential elements of the regulatory pathway for lipid synthesis function in liver as they do in cultured cells.

Alleles↗
PubMed1998

Quality assurance in aquatic biology--a user's perspective.

The essential elements of developing biological quality assurance systems are presented in terms of the 4M principles. These relate to methods, manpower, materials, and machines. The use of international or European standards is recommended where such standards exist. Users must be sure that these are appropriate to their specific needs as standardisation can require considerable compromise. Examples of limitations in international standards are given with reference to the coliform isolation by membrane filtration, Daphnia magna acute toxicity test and the luminescent bacteria test. The criteria for the selection and use of national methodologies are considered using macroinvertebrate, macrophytes, imposex, and the oyster embryo bioassay as examples. In recognising that the main resource in science is the skill, training, and dedication of the scientists themselves, the United Kingdom has developed a quality initiative aimed at best utilising the human resource, the so-called Investors in People (IIP) initiative. This contains the essential elements of any quality system: commitment, planning, action, and evaluation. Quality aspects of the materials and the machines used in biological analyses are briefly considered.

Environmental Monitoring↗
PubMed2006

The role of the consent document in informed consent for pediatric leukemia trials.

PURPOSE: To examine both the use of the consent document during the informed consent process for pediatric leukemia clinical trials, as well as relationships between the use of the document and parental understanding of essential elements of informed consent. METHODS: Participants included 140 parents of children diagnosed with pediatric leukemia. Informed consent conferences in which randomized clinical trials were discussed were observed, audiotaped, and coded for specific behaviors. Parents were also interviewed within 48 h of their participation in informed consent conferences. RESULTS: Observations revealed that 74% of cases included explanation of consent documents during consent conferences. Parents who reported that they read the consent document were more likely to understand differences between the clinical trial and off study therapy and were more likely to understand the right to withdraw. Reading of the consent document was not associated with understanding of voluntariness. In comparison to racial/ethnic majority parents, racial/ethnic minority parents were less likely to report that they read the consent document, understand voluntariness or the right to withdraw, and were less likely to be able to distinguish between the clinical trial and off study therapy. Low SES was associated with a lower probability of reading the consent document and being able to distinguish between clinical trials and off study therapy. CONCLUSIONS: Attention to the importance of reading the consent document and improving communication during consent conferences is likely to enhance understanding of essential elements of informed consent.

Adolescent↗
PubMed1997

The structure of an essential splicing element: stem loop IIa from yeast U2 snRNA.

BACKGROUND: Eukaryotic genes are usually transcribed as precursor mRNAs which are then spliced, removing introns to produce functional mRNAs. Splicing is performed by the spliceosome and provides an important level of post-translational control of gene expression. Stem loop IIa from U2 small nuclear (sn)RNA is required for the efficient association of the U2 small nuclear ribonuclear protein (snRNP) with the nascent spliceosome in yeast. Genetic analysis suggests that stem loop IIa is involved in RNA-protein interactions early in splicing, and it may also interact with other RNA sequences in U2. The sequence of loop IIa is well conserved, consistent with the idea that this loop is important for function. RESULTS: We have solved the structure of U2A, a 20-base analogue of stem loop IIa from Saccharomyces cerevisiae, using NMR and restrained molecular dynamics. In the process, we have demonstrated the efficacy of a new structure calculation protocol, torsion angle molecular dynamics. The structure that has emerged, which is consistent with the in vivo chemical protection data available for stem loop IIa in the context of intact U2 snRNA, contains a sheared GA pair followed by a U-turn in the loop. The U-turn conformation, which resembles the U-turns in tRNA anticodon loops, makes this stretch of U2 snRNA an obvious target for interactions with proteins and/or other RNA sequences. CONCLUSIONS: The phenotypes of many stem loop IIa mutants can be rationalized assuming that the U-turn conformation in the loop must be preserved for efficient splicing. This observation, combined with the phylogenetic conservation of its sequence, suggests that the conformation of the loop of stem loop IIa is essential for its function in pre-mRNA splicing.

Base Sequence↗
PubMed2006

Incidence and predictors of difficult and impossible mask ventilation.

BACKGROUND: Mask ventilation is an essential element of airway management that has rarely been studied as the primary outcome. The authors sought to determine the incidence and predictors of difficult and impossible mask ventilation. METHODS: A four-point scale to grade difficulty in performing mask ventilation (MV) is used at the authors' institution. They used a prospective, observational study to identify cases of grade 3 MV (inadequate, unstable, or requiring two providers), grade 4 MV (impossible to ventilate), and difficult intubation. Univariate and multivariate analyses of a variety of patient history and physical examination characteristics were used to establish risk factors for grade 3 and 4 MV. RESULTS: During a 24-month period, 22,660 attempts at MV were recorded. 313 cases (1.4%) of grade 3 MV, 37 cases (0.16%) of grade 4 MV, and 84 cases (0.37%) of grade 3 or 4 MV and difficult intubation were observed. Body mass index of 30 kg/m or greater, a beard, Mallampati classification III or IV, age of 57 yr or older, severely limited jaw protrusion, and snoring were identified as independent predictors for grade 3 MV. Snoring and thyromental distance of less than 6 cm were independent predictors for grade 4 MV. Limited or severely limited mandibular protrusion, abnormal neck anatomy, sleep apnea, snoring, and body mass index of 30 kg/m or greater were independent predictors of grade 3 or 4 MV and difficult intubation. CONCLUSIONS: The authors observed the incidence of grade 3 MV to be 1.4%, similar to studies with the same definition of difficult MV. Presence of a beard is the only easily modifiable independent risk factor for difficult MV. The mandibular protrusion test may be an essential element of the airway examination.

Adult↗
PubMed2001

The impact and management of cancer-related fatigue on patients and families.

Fatigue has been identified as both a chronic and recurrent problem for individuals diagnosed with and treated for cancer, yet there is little information on how to manage the impact of fatigue. Describing what happens to individuals and their families as a result of fatigue and identifying what individuals do to manage or reduce the impact of fatigue are essential elements in determining multidimensional nursing interventions. The purpose of this pilot study was to examine the impact of fatigue on individuals with cancer of the lung and their families, and explore how they managed as a result of the fatigue. A semi-structured interview guide was used with 22 lung cancer patients and 14 family members six weeks post completion of radiation therapy. Results indicated that fatigue was not reported as a major concern by many of the participants in this study. For those who did experience fatigue, it was considered an inconvenience and a frustration that had to be dealt with for a limited time period. Some patients appeared to gradually adjust and accommodate to the fatigue and were not really aware of the changes that took place over time. Over half of the family members felt more of the impact of fatigue than did their loved ones. Family subtly assumed or took over responsibilities and activities the patient could no longer perform. The symptom of fatigue has been well documented in the cancer experience as both a chronic and recurrent problem for individuals diagnosed with and treated for cancer. The emphasis of previous work has been on deriving a conceptual definition of fatigue, achieving consensus on a definition, and developing theoretical frameworks to guide further study of this complex construct. Fatigue has been conceptualized as a multidimensional phenomenon, attributable to multiple causes and having a negative effect on quality of life (Piper, 1993; Tiesinga, Dasson, & Halfens, 1996). Describing what happens to individuals and their families as a result of fatigue and identifying what individuals do to manage or reduce the effects caused by the fatigue are essential elements in determining multidimensional nursing interventions.

Adaptation, Psychological↗
PubMed2001

A novel upstream RNA polymerase III promoter element becomes essential when the chromatin structure of the yeast U6 RNA gene is altered.

The Saccharomyces cerevisiae U6 RNA gene, SNR6, possesses upstream sequences that allow productive binding in vitro of the RNA polymerase III (Pol III) transcription initiation factor IIIB (TFIIIB) in the absence of TFIIIC or other assembly factors. TFIIIC-independent transcription of SNR6 in vitro is highly sensitive to point mutations in a consensus TATA box at position -30. In contrast, the TATA box is dispensable for SNR6 transcription in vivo, apparently because TFIIIC bound to the intragenic A block and downstream B block can recruit TFIIIB via protein-protein interactions. A mutant allele of SNR6 with decreased spacing between the A and B blocks, snr6-Delta42, exhibits increased dependence on the upstream sequences in vivo. Unexpectedly, we find that in vivo expression of snr6-Delta42 is much more sensitive to mutations in a (dT-dA)(7) tract between the TATA box and transcription start site than to mutations in the TATA box itself. Inversion of single base pairs in the center of the dT-dA tract nearly abolishes transcription of snr6-Delta42, yet inversion of all 7 base pairs has little effect on expression, indicating that the dA-dT tract is relatively orientation independent. Although it is within the TFIIIB footprint, point mutations in the dT-dA tract do not inhibit TFIIIB binding or TFIIIC-independent transcription of SNR6 in vitro. In the absence of the chromatin architectural protein Nhp6, dT-dA tract mutations are lethal even when A-to-B block spacing is wild type. We conclude that the (dT-dA)(7) tract and Nhp6 cooperate to direct productive transcription complex assembly on SNR6 in vivo.

AT Rich Sequence↗
PubMed1998

Anatomical comparison of the macaque and marsupial visual cortex: common features that may reflect retention of essential cortical elements.

This study identifies fundamental anatomical features of primary visual cortex, area V1 of macaque monkey cerebral cortex, i.e., features that are present in area V1 of phylogenetically distant mammals of quite different lifestyle and features that are common to other regions of cortex. We compared anatomical constituents of macaque V1 with V1 of members of the two principal marsupial lines, the dunnart and the quokka, that diverged from the eutherian mammalian line over 135 million years ago. Features of V1 common to both macaque and marsupials were then compared with anatomical features we have previously described for macaque prefrontal cortex. Despite large differences in overall area and thickness of V1 cortex between these animals, the absolute size of pyramidal neurons is remarkably similar, as are their specific dendritic branch patterns and patterns of distribution of intrinsic axons. Pyramidal neuron patchy connections exist in the supragranular V1 in both the marsupial quokka and macaque as well as in macaque prefrontal cortex. Several specific types of aspinous interneurons are common to area V1 in both marsupial and macaque and are also present in macaque prefrontal cortex. Spiny stellate cells are a common feature of the thalamic-recipient, mid-depth lamina 4 of V1 in all three species. Because these similarities exist despite the very different lifestyles and evolutionary histories of the animals compared, this finding argues for a highly conserved framework of cellular detail in macaque primary visual cortex rather than convergent evolution of these features.

Anatomy, Artistic↗
PubMed1980

[Supply of some essential trace elements to the Hungarian population].

The authors determined the copper, zinc, chromium, cobalt, manganese, iron and nickel contents in 703 samples of animal foods (meat, offals, milk, eggs) from different parts of Hungary and of 370 samples of fruits and vegetables. Calculations based on consumption data from the Central Board of Statistics showed that the copper and iron intakes of the population are lower than those suggested the FAO/WHO. When infants are given exclusively ready-to-use baby foods produced on a milk-only basis (Hungarian products and products imported from western countries), their supply is still less favourable than that to adults. Whereas human milk meets also the requirements of trace elements optimally, ready-to-use baby foods produced on a milk-only basis supply not more than 10--15% on the required copper and 20--35% of the required iron. The authors focus attention on the risk of inadequate supply of trace elements in childhood, the negative implications of which will still manifest themselves in adulthood for a long time.

Animals↗
PubMed1984

[Supplying various age groups with certain essential trace elements].

Investigations revealed a very good correspondence of the intake of trace elements, calculated from per capita food consumption, with the analytically determined values of the full daily diet. It is above all the copper intake and, to a lesser degree, the zinc and iron intake, which deviate from the generally recommended values. The results obtained for the different age groups indicate the copper intake to be sufficient only with children up to six years old. The iron supply of adolescent girls and old people should be improved. As is well known, the utilization of trace elements is influenced by many dietetic and individual factors. Therefore, further investigations must be carried out to decide whether the analytically determined intake of trace elements guarantees an adequate supply or whether disturbances often occurring with a slight under-supply must be taken into consideration.

Adult↗
PubMed2001

Interaction of chemical species with biological regulation of the metabolism of essential trace elements.

Variations in the chemical speciation of dietary trace elements can result in the provision of different amounts of these micronutrients to the organism and might thus induce interactions with trace-element metabolism. The chemical species of Zn, Fe, Cu, and Mn can interact with other components of the diet even before reaching the site of absorption, e.g. by formation of poorly soluble complexes with phytic acid. This might considerably modify the amount of metabolically available trace elements; differences between absorptive capacity per se toward dietary species seems to be less important. Homeostasis usually limits the quantities of Zn, Fe, Cu, and Mn transported from the gut into the organism, and differences between dietary species are largely eliminated at this step. There is no homeostatic control of absorption of Se and I, and organisms seem to be passively exposed to influx of these micronutrients irrespective of dietary speciation. Inside the organism the trace elements are usually converted into a metabolically recognizable form, channeled into their biological functions, or submitted to homeostatically controlled excretion. Some dietary species can, however, be absorbed as intact compounds. As long as the respective quantities of trace elements are not released from their carriers, they are not recognized properly by trace element metabolism and might induce tissue accumulation, irrespective of homeostatic control.

Animals↗
PubMed2004

Regional distribution of manganese, iron, copper, and zinc in the rat brain during development.

Manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn) concentrations were determined in the brain regions of normal 1-, 3-, 5-, 7-, 14-, 21-, 42-, 77-, and 147-day-old Wistar rats using inductively coupled plasma mass spectrometry (ICP-MS), and their maps were illustrated in color to visually compare the distribution of the elements at various stages of the growth process. Sagittal slices (1-mm thickness) sectioned at the level of the substantia nigra were divided into 18 regions, and the small slice samples were digested in microwave-assisted closed vessels for ICP-MS measurement. Mn, Fe, Cu, and Zn concentrations increased region-specifically with age, and their distributional maps showed some characteristics. These findings are discussed in terms of needs for these trace elements in the normal brain. Among new findings about their brain distribution, it is especially noteworthy that higher concentrations of Mn, Fe, and Zn were observed in the substantia nigra compared with those in neighboring regions. The mapping method in this work is expected to open up possibilities for screening of the in vivo element-element interrelationships among these essential elements.

Age Factors↗