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PubMed1997

Recreation and risk: potential exposure.

The Department of Energy and other federal facilities are reclaiming land through the process of remediation and restoration, and this land will eventually be turned over for future land uses that may involve recreation. Understanding the amount of recreation that is likely (and thus individual exposure) is an essential element in decisions about cleanup standards. In this article the number of days people engage in different recreational activities as a measure of potential exposure is examined. People attending a Mayfest celebration (n = 399) and the Palmetto Sportsmen's Classic (n = 285) in Columbia, SC, were interviewed regarding their recreational activities. In most cases reported in the literature, recreational activities are examined as the mean number of days people engage in each activity per year, but to determine risk it is essential to know the distribution of these activities. In descending order of frequency, people attending the Mayfest reported their activities as birdwatching, photographing, fishing, hiking, camping, and hunting. There were significant gender differences in the frequency of activities, with men spending more days in every activity except birdwatching and photography. There were ethnic differences in recreation, with whites engaging in higher levels of most recreational activities than blacks, but the percentage of black men who reported fishing more than 100 d per year was greater than for white men. Most people reported their participation in most activities less than 30 d per year; however, a higher percentage of people reported participating in photography, birdwatching, and fishing more than 30 d per year compared to the other activities. Further, individuals at the Sportsman's Classic reported far higher rates of hunting and fishing per year than the general public. These data can be used to examine potential exposure of recreationists on remediated and restored land. The data clearly indicate that over 25% of the people engage in at least one recreational activity over 20 d per year, and thus exceed the Department of Energy's 14-d recreation assumption in its future land use document.

Cohort Studies↗

PubMed2001

Trafficking and assembly of the cytoadherence complex in Plasmodium falciparum-infected human erythrocytes.

After invading human erythrocytes, the malarial parasite Plasmodium falciparum, initiates a remarkable process of secreting proteins into the surrounding erythrocyte cytoplasm and plasma membrane. One of these exported proteins, the knob-associated histidine-rich protein (KAHRP), is essential for microvascular sequestration, a strategy whereby infected red cells adhere via knob structures to capillary walls and thus avoid being eliminated by the spleen. This cytoadherence is an important factor in many of the deaths caused by malaria. Green fluorescent protein fusions and fluorescence recovery after photobleaching were used to follow the pathway of KAHRP deployment from the parasite endomembrane system into an intermediate depot between parasite and host, then onwards to the erythrocyte cytoplasm and eventually into knobs. Sequence elements essential to individual steps in the pathway are defined and we show that parasite-derived structures, known as Maurer's clefts, are an elaboration of the canonical secretory pathway that is transposed outside the parasite into the host cell, the first example of its kind in eukaryotic biology.

Amino Acid Sequence↗

PubMed2005

[Ulcus cruris venosum--therapeutic principles].

An essential element in the management of ulcus cruris venosum is the treatment of the cause applying compression. For this purposes, various systems are currently available, the application of which, however, must always be undertaken with consideration being given to the individual situation and possible contraindications. Topical treatment of chronic wounds, including ulcus cruris venosum, is performed stage-oriented, in accordance with the principles of moist wound care. The critical selection of the most appropriate dressing materials for the case presenting is essential for a treatment that is both medically and economically justifiable. An aim of the treatment continues to be the curtailment of the still too long treatment times, and to reduce the number of recurrences.

Animals↗

PubMed1999

Conversion of a reporter gene for mitochondrial gene expression using iterative mega-prime PCR.

Mammalian mitochondria possess their own multicopy genome, mtDNA. Although much is known about mtDNA replication and transcription, our knowledge of the mechanisms governing mt-RNA processing, stability and translation remains rudimentary. We have taken a step towards addressing these issues by altering the luciferase reporter gene to accommodate the variation in mitochondrial codon recognition. 19 essential substitutions have been generated by an iterative mega-primer PCR technique. To mimic mt-mRNA species and to optimise intramitochondrial translation, further engineering has produced a template which, when transcribed in vitro, generates an RNA species with only two nucleotides upstream from the initiation codon, an absence of a 3' untranslated region and a polyadenylated tail of 40 residues. It is intended that mt-luciferase (mt-luc) RNA will be an excellent reporter for revealing cis-acting elements essential for in organello RNA processing, maturation and expression. Additionally, the mt-luc gene can be readily incorporated into any novel mitochondrial transducing vectors to assess intra-organellar transcription and translation.

DNA Primers↗

PubMed1997

Mutational characterization of promoter regions recognized by the Salmonella dublin virulence plasmid regulatory protein SpvR.

The virulence plasmid-encoded spv regulon is essential for virulence of Salmonella dublin in mice. The spvR gene product belongs to the LysR family of transcriptional regulator proteins. SpvR induces the expression of the spvABCD operon and positively regulates its own expression. DNase I protection analysis with purified SpvR fusion proteins identified SpvR binding sites within the spvA and spvR promoters (P. Grob and D. G. Guiney, J. Bacteriol. 178:1813-1820, 1996). We have used PCR mutagenesis, combined with functional selection for reduced SpvR affinity, to define the DNA elements essential for SpvR binding. For the spvR promoter fragment, a screen for reduced expression was also applied. Sequence analysis of the resulting mutant fragments reveals that the base pair changes are clustered in distinct regions. Determination of the apparent dissociation constants of SpvR for the mutant promoters showed that the spvA LysR-type motif and the upstream palindromic sequences of both promoters play an important role in SpvR recognition.

Animals↗

PubMed1991

Properties of the promoter region of the T18d (T13c) Tla gene.

The T18d (formerly T13c) gene of BALB/c mice belongs to the category of Tla genes which is expressed by both thymocytes and TL+ T-cell leukemias. To elucidate the regulation of T18d, different restriction fragments of the 5' flanking region between -457 and +146 were linked to the chloramphenicol acetyltransferase (CAT) gene and transfected into TL+ and TL- cells. By comparison of transiently expressed CAT activity among cells transfected with different CAT constructs, the results suggest that determination of TL+ vs TL- phenotypes is located within the region -105 to -33, and that an element essential to T18d expression resides within the region -33 to +54. Putative DNA-binding factors characterizing particular cell types and displaying selective affinity for particular T18d restriction fragments were identified by electrophoretic mobility shift assays with nuclear extracts (NEs). Two factors (or complexes) which bound specifically to the T18d fragment -105 to -33 were expressed preferentially in TL+ cells and thus may be involved in determining the tissue-selective expression of T18d. The close proximity of negative and positive cis-acting elements within the promoter region is consistent with regulation of T18d gene expression by a variety of trans-acting factors whose production is attuned to development and differentiation. The data provided may serve as a guide to study the regulation of other categories of Tla genes that are normally silent in thymocytes but may become expressed by leukemia cells.

Animals↗

PubMedDate not supplied

Lactate as a pivotal element in neuron-glia metabolic cooperation.

Lactate has been considered for a long time as a metabolic waste and/or a sign of hypoxia in the central nervous system. Nevertheless, clear evidence that lactate can constitute an adequate energy substrate for brain tissue has been provided as early as in the 1950s with the pioneering work of McIlwain in brain slices. Over the years, several studies using different approaches have confirmed that lactate is efficiently oxidized by brain cells in vitro. Moreover, lactate has been shown under certain circumstances to have a neuroprotective effect and support neuronal activity. Similar confirmation of lactate utilization in vivo as well as putative neuroprotection in various excitotoxic models has been provided. Lactate was even shown to restore cognitive performance upon an hypoglycemic episode in humans. More recently, it was proposed that lactate could be produced by astrocytes and released in the extracellular space to form a pool readily available for neurons in case of high energy demands. Several elements support the concept of a lactate shuttle between astrocytes and neurons in the central nervous system. Among them, the description of specific monocarboxylate transporters found on both astrocytes and neurons is an important observation consistent with this concept. Interestingly, lactate shuttles between different cell types within the same organ have been described outside the central nervous system, notably in muscle and testis. Thus, lactate is emerging as a valuable intercellular exchange molecule in different systems including the brain where it might be an essential element of neuron-glia metabolic interactions.

Central Nervous System↗

PubMed1997

Zona pellucida glycoprotein mZP3 bioactivity is not dependent on the extent of glycosylation of its polypeptide or on sulfation and sialylation of its oligosaccharides.

During fertilization in mice, free-swimming sperm bind to mZP3, one of three egg zona pellucida glycoproteins. Sperm recognize and bind to specific serine/threonine-linked (O-linked) oligosaccharides located at the mZP3 combining site for sperm. Shortly after binding to mZP3, sperm undergo the acrosome reaction, a form of cellular exocytosis. Here, we examined the influence of extent of glycosylation, sulfation, and sialylation of mZP3 (M(r) approximately 65,000-100,000) on its bioactivity; i.e. its ability to inhibit binding of sperm to eggs and to induce the acrosome reaction in vitro. Low (av. M(r) approximately 70,000), medium (av. M(r) approximately 82,000), and high (av. M(r) approximately 94,000) M(r) fractions of mZP3 were purified and shown to vary in extent of asparagine-linked (N-linked) glycosylation. All three size-fractions exhibited bioactivity, suggesting that the ability of mZP3 to inhibit binding of sperm to eggs is not related to the extent of glycosylation of its polypeptide (M(r) approximately 44,000). Digestion of mZP3 by neuraminidase decreased its average M(r) from approximately 83,000 to approximately 77,000 and increased its average pI from approximately 4.7 to approximately 6.0, but did not significantly affect mZP3 bioactivity. Terminal sialic acid largely accounts for the glycoprotein's acidic nature, but is not an essential element of the mZP3 combining site for sperm. Experiments with stably transfected embryonal carcinoma (EC) cells that secrete bioactive EC-mZP3 revealed that, of the sulfate present, approximately 70-75% was located on N-linked and approximately 25-30% on O-linked oligosaccharides. EC-mZP3 devoid of sulfate inhibited binding of sperm to eggs and induced the acrosome reaction to the same extent as sulfated EC-mZP3. These results suggest that sulfation of EC-mZP3 oligosaccharides is not essential for bioactivity. Overall, these findings contrast with those reported for certain other glycoproteins involved in cellular adhesion that require sulfate and/or sialic acid for bioactivity.

Animals↗

PubMed2002

Planning youth violence prevention efforts: decision-making across community sectors.

PURPOSE: To identify practical components of decision-making for youth violence prevention program planning and to identify differences in decision-making across various provider sectors of the community. METHODS: Data were collected in seven focus groups (n = 82) representing seven key sectors of the community involved in youth violence prevention activities (e.g., educators, law enforcement officers, and healthcare providers). Discussion was guided by a series of open-ended questions that we developed. Transcript-based content analysis using NVivo software identified common themes among and across sectors. RESULTS: Similarities and differences in planning and selecting prevention efforts were found across sectors. Educators targeted behaviors that disrupt the school process, while other sectors focused on precursors and concurrent factors of violent behavior and the development of desirable behaviors. Public health and public policy participants underscored outcome measures, benchmarks, and a match between funding and effective programs as essential elements. Youth identified the need for respect from adults and the recognition of positive youth behaviors. All groups noted the lack of a systematic method of considering potential programs, the importance of youth and parental involvement in efforts, the lack of a scientific base for many programs, concerns about exposure to violence, and inappropriate role models in multiple environments. CONCLUSIONS: Healthcare providers often participate in the development of youth violence prevention programs. Understanding similarities and differences in focus among key sectors of the community is essential in developing coordinated interdisciplinary approaches.

Adolescent↗

PubMed2005

Time dependent study to evaluate the efficacy of zinc on hepatic marker enzymes and elemental profile in serum and liver of protein deficient rats.

This study was designed to determine the time dependent protective effects of zinc sulfate on the serum and liver marker enzymes along with elemental profile in protein deficient Sprague Dawley (S.D.) female rats. Zinc sulfate in the dose of 227 mg/l in drinking water was administered to normal control as well as protein deficient rats for a total duration of 8 weeks. The effects of different treatments were studied on enzymes like alkaline phosphatase (ALP), aspartate aminotransferases (AST) and alanine aminotransferases (ALT) in rat serum at different time intervals of 1, 2, 4 and 8 weeks and in the rat liver at the end of study. The status of different essential elements in liver was also studied. The serum ALP activity got significantly depressed when estimated at the intervals of 4 and 8 weeks. Activity of serum ALT was significantly increased after 4 weeks interval in protein deficient rats and the increasing trend continued upto 8 weeks of protein deficiency. On the other hand, activity of AST showed a significant increase just after 2 weeks and activity continued to be increased up to 8 weeks. Moreover activities of all the hepato marker enzymes showed a significant increase in liver of protein deficient rats. Interestingly, supplementation of Zn to protein deficient rats helped in regulating the altered activities of ALP, AST and ALT both in serum and liver. However, zinc treatment alone to normal rats did not indicate any significant change in the activities of all the enzymes in liver as well serum except at the interval of 2 weeks where a marginal increase in the activity of AST was seen. It has also been observed that concentrations of zinc, copper, iron and selenium were found to be decreased significantly in protein deficient animals. However, the levels of these elements came back to within normal limits when zinc was administered to protein deficient rats.

Alanine Transaminase↗

PubMed1982

A new concept for quality control of clinical laboratory investigations in the light of clinical requirements and based on reference method values.

Quality control is an essential element in clinical laboratory investigations. In the basic programs for quality control used in recent years accuracy control has been carried out through a comparison with method-dependent assigned values. With this system the "accuracy" of results from different laboratories is relative, and comparability is assured only when the laboratories use the same analytical method. Considering the steadily increasing variety of methods and equipment, a meaningful exchange of information in patient care, teaching and research is becoming more and more difficult; but clinical requirements make such an exchange essential. In this paper a new concept for quality control is presented for discussion. In the basic program incorporating the new concept the method-dependent assigned values are replaced by reference method values, which are method-independent. In addition to accuracy control, an ongoing monitoring procedure using a Shewhart control chart is also carried out. The maximum allowable day-to-day imprecision and the maximum allowable deviation from the reference method value are fixed on the basis of clinical requirements. This means that the ratio of biological variation to analytical between-day imprecision should be greater than or equal to 2. If the biological variation is unknown, then the reference interval is used in its place; the quotient, reference interval/analytical between-day imprecision, should then be greater than or equal to 8. The decision limits for the interlaboratory surveys should be fixed in an analogous manner independent of the analytical method. After the introduction of quality control based on the new concept the results from different laboratories would be comparable to the extent dictated by clinical requirements. The main principles underlying the new concept and the effects of using the new approach are presented for discussion, and the reader is invited to submit comments in writing.

Blood Glucose↗

PubMed1991

Inhibition of pre-mRNA splicing by antisense RNA in vitro: effect of RNA containing sequences complementary to introns.

The objective of the experiments described in this paper was to test the potential of antisense RNAs complementary to the internal portion of an intron to inhibit the splicing process and to determine the mechanism of such inhibition. The results obtained indicate that RNA fragments complementary to the internal portion of an intron can effectively inhibit the splicing of pre-mRNA. Inhibition was observed only with antisense RNA complementary to pre-mRNA suggesting that the inhibitory effect was due to the formation of a hybrid with the corresponding portion of the pre-mRNA's intron. The observed inhibition was not due to interference with possible intron elements essential for the splicing process, for the deletion of the sequences complementary to inhibitory antisense RNA from the corresponding pre-mRNA molecule did not affect the efficiency of a splicing reaction, and the addition of antisense RNA to pre-mRNA mutants carrying such deletions did not result in any inhibition. Our results indicate that the observed inhibition is a function of the length of the antisense RNA expressed as a fraction of an intron with which it interacts when antisense RNA is modified by incorporation of a "hinge" element, it loses its inhibitory potential suggesting that the inhibitory effect is probably due to limitation of conformational flexibility of an intron.

Animals↗

PubMed1996

Requirement of distal and proximal promoter sequences for chromatin organization of the osteocalcin gene in bone-derived cells.

The osteocalcin (OC) gene encodes a 10 Kda bone-specific protein which is expressed with the onset of mineralization during the differentiation of normal diploid osteoblasts. We have previously reported that transcriptional activation of this gene is accompanied by the presence of two DNase I hypersensitive sites, both located in the promoter region spanning key basal (proximal site, -170 to -70) and steroid-dependent enhancer (distal site, -600 to -400) elements. Here, we have examined stably transfected ROS 17/2.8 cell lines carrying OC promoter-reporter transgenes which contain a series of 5'-deletions and determined the effects of these truncations on the chromatin organization. It has been found that: (1) DNase I hypersensitivity at -600 is not a requirement for vitamin D-dependent transcriptional upregulation; (2) basal transcriptional activity and proximal nuclease hypersensitivity depend exclusively on protein-DNA interactions occurring within the proximal promoter region, and (3) within the chromatin context, the proximal 100 bp promoter fragment, containing essential elements such as the OC box (-99 to -76) and TATA box (-44 to -31), is insufficient to support formation of the proximal nuclease hypersensitive site and transcriptional activity.

Animals↗

PubMed1995

Characterization of protein complexes formed on the repressor elements of the human tumor necrosis factor alpha gene.

Human tumor necrosis factor alpha (TNF-alpha) is an important cytokine responsible for pleiotropic effects in vivo. The expression of TNF-alpha is under both positive and negative regulation. Previously we showed that a 108 bp region (-280 to -172) in the TNF-alpha promoter represses TNF-alpha transcription in U937 cells. We also demonstrated that a smaller region of the promoter spanning base pairs -254 and -230 is sufficient for repressor function. This 25 bp TNF-alpha repressor site (TRS) contains a 10 bp sequence homologous to the binding site of activator protein AP-2, yet it does not bind the AP-2 protein. In this study, we demonstrate that this 10 bp core sequence is an essential element for the repressor function of the TRS. Using gel retardation analysis with the 108 bp repressor element and the TRS as probes, multiple specific DNA binding complexes have been identified from U937 nuclear extracts. The complexes B, C, and D on the 108 bp probe and the three major complexes on the 25 bp TRS probe are also present in Jurkat and Mono Mac 6 cells, and their abundance in these cell lines seems to correlate with their postulated repressor function. We have demonstrated that the major TRS binding proteins, with estimated MWs of 30-60 kD, copurify on a heparin agarose column and on a DNA affinity column conjugated with the 10 bp core sequence.

Base Sequence↗

PubMed2005

Transcriptional regulation of the circadian clock operon kaiBC by upstream regions in cyanobacteria.

In the cyanobacterium, Synechococcus elongatus PCC 7942, the kaiBC operon is upregulated by the KaiA protein and downregulated by the KaiC protein to generate circadian oscillation. We investigated the regulation of kaiBC transcription. A primer extension and deletion analyses of the upstream region mapped the sufficient promoter region (SPR) to base pairs -55 to +1 (the transcription start site, TSS) and identified a constitutive negative regulatory region upstream of the SPR (base pairs -897 to -56) that extended into the coding sequence of kaiA. Base-pair substitution within the SPR identified a sequence from -52 to -28 that was the essential element for transcription. Most of the examined sequences drove rhythmic expression of a luxAB reporter that was similar to the expression driven by the kaiBC promoter (PkaiBC) and responded to the overexpression of kaiA or kaiC, even in a promoter activity range of 1-8000%. These results indicate that circadian feedback regulation by KaiA and KaiC is addressed to a global step preceding transcription driven by PkaiBC. However, increasing or decreasing the intrinsic activity of PkaiBC greatly affected the rhythm, suggesting that constitutive adjustment of PkaiBC activity by the sequences identified here is essential for the oscillator.

Bacterial Proteins↗

PubMed1994

The cadmium toxicity hypothesis of aging: a possible explanation for the zinc deficiency hypothesis of aging.

Although cadmium and zinc have similar chemical properties, they affect living organisms diversely: while zinc is an essential element for growth, development and functioning of all living cells, cadmium is a highly toxic material. Cadmium has an extremely long biological half-life and may be considered a cumulative toxin. It has been shown to have sterilizing, teratogenic and carcinogenic effects and most of these effects could be reduced or even prevented by zinc administration. An increase in cadmium concentration with age has been proven in various species and in different tissues and these facts led some investigators to the assumption that cadmium accumulation might play an important role in senescence. Zinc essentiality and the lack of a reliable index of intracellular zinc status, formed the rationale for the zinc deficiency hypothesis of aging. This hypothesis suggests a gradual time related zinc deficiency occurring in each living cell, making zinc less available for its metalloenzymes. The sum of all deleterious effects resulting from the distorted function of different zinc enzymes, is later manifested as aging processes. When cadmium concentration increases, zinc concentration in various tissues decreases. Cadmium may inhibit zinc activities at many stages, interfering with zinc absorption, distribution to different tissues and transport into cells or into several intracellular structures. Therefore, it is reasonable to assume that a slowly developing cadmium toxicity may result in a gradual time related zinc deficiency.

Aging↗

PubMed1990

[Principles and indications of electrostimulation of the urinary bladder].

Neurostimulation to restore the essential elements of lower urinary tract function is a very promising approach in the management of the neuropathic bladder. The goal of neurostimulation is to restore the three main functions of the lower urinary tract: the reservior capacity of the bladder, the sphincteric activity of the continence mechanism, and the ability of the bladder to evacuate completely. In extensive experimental studies conducted over the past 18 years, the physiological foundations of micturition and sphincteric control were investigated, which made the clinical application of neurostimulation in the management of the neurogenic bladder possible. In human studies, the essential experimental model of ventral root stimulation after dorsal rhizotomy and selective peripheral neurotomy proved to be the most successful. To date, over 220 patients have been treated, of whom 35 have spinal cord injury or severe neuropathy and received multiple sacral root implants. 25 of the 35 patients are evaluable, 15 (60%) of these achieved the three goals of the study: complete continence, restoration of reservoir function with adequate capacity, and voiding to neurostimulation with minimal residual urine or none. The remaining 185 patients with a variety of voiding dysfunctions classified under four main headings: 1) urge incontinence; 2) post-prostatectomy incontinence; 3) pelvic dysfunction syndrome in the male; 4) pelvic dysfunction syndrome in the female were treated by single electrode implantation in order to modulate spastic voiding dysfunction and pelvic floor activity. Success rates (improvement of 50% or more) were 72%, 38%, 46%, and 47% in the four groups, respectively.

Animals↗

PubMed2006

The effect of modified citrus pectin on urinary excretion of toxic elements.

This study was undertaken to evaluate the effect of modified citrus pectin (MCP) on the urinary excretion of toxic elements in healthy individuals. MCP is a reduced molecular weight pectin (weight-average molar mass = 15,400) that is mostly linear homogalacturonan with a 3.8% degree of esterification and approximately 10% rhamnogalacturonan II based on the presence of 2-keto-3-deoxy-octonic acid. Subjects ingested 15 g of MCP (PectaSol, EcoNugenics Inc., Santa Rosa, California 95407) each day for 5 days and 20 g on day 6. Twenty-four hour urine samples were collected on day 1 and day 6 for comparison with baseline. The urine samples were analysed for toxic and essential elements. In the first 24 h of MCP administration the urinary excretion of arsenic increased significantly (130%, p < 0.05). On day 6, urinary excretion was increased significantly for cadmium (150%, p < 0.05). In addition, lead showed a dramatic increase in excretion (560%, p < 0.08). This pilot trial provides the first evidence that oral administration of MCP increases significantly the urinary excretion of toxic metals in subjects with a 'normal' body load of metals. It is suggested that systemic chelation of toxic metals by MCP may in part be attributable to the presence of rhamnogalacturonan II, which has been shown previously to chelate metals.

Adult↗