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At least 793 records · Page 44Linked to original sources
PubMed2006

Serine/arginine-rich splicing factors belong to a class of intrinsically disordered proteins.

Serine/arginine-rich (SR) splicing factors play an important role in constitutive and alternative splicing as well as during several steps of RNA metabolism. Despite the wealth of functional information about SR proteins accumulated to-date, structural knowledge about the members of this family is very limited. To gain a better insight into structure-function relationships of SR proteins, we performed extensive sequence analysis of SR protein family members and combined it with ordered/disordered structure predictions. We found that SR proteins have properties characteristic of intrinsically disordered (ID) proteins. The amino acid composition and sequence complexity of SR proteins were very similar to those of the disordered protein regions. More detailed analysis showed that the SR proteins, and their RS domains in particular, are enriched in the disorder-promoting residues and are depleted in the order-promoting residues as compared to the entire human proteome. Moreover, disorder predictions indicated that RS domains of SR proteins were completely unstructured. Two different classification methods, the charge-hydropathy measure and the cumulative distribution function (CDF) of the disorder scores, were in agreement with each other, and they both strongly predicted members of the SR protein family to be disordered. This study emphasizes the importance of the disordered structure for several functions of SR proteins, such as for spliceosome assembly and for interaction with multiple partners. In addition, it demonstrates the usefulness of order/disorder predictions for inferring protein structure from sequence.

Amino Acids↗
PubMed1995

Gene therapy of rheumatoid arthritis via cytokine regulation: future perspectives.

Following many years of research using isolated human tissues and animal models, sufficient knowledge concerning rheumatoid arthritis has accumulated so that novel immunotherapies have been proposed. Biological agents are being tested in clinical trials and include antibodies to T cells and cytokines. Currently the most promising of these is intravenously administered neutralizing anti-TNF antibody. In order to establish disease modification, however, therapy needs to be delivered continuously over the long term. The prospect of delivering cytokine inhibitors as genetic material (naked DNA), viruses or in engineered autologous cells is considered as one option for achieving this goal. We compare two strategies, firstly, using immobile cells such as fibroblasts, myoblasts or keratinocytes, and secondly, the migratory cells of the immune system. The former provides a reservoir of systemic delivery of the therapeutic protein whereas the latter provides targeted delivery determined by the antigen specificity of the immune cells. Early validation has begun in animal models of rheumatoid arthritis.

Animals↗
PubMed1997

Osmoregulation and glycerol metabolism in the yeast Saccharomyces cerevisiae.

Glycerol is the main compatible solute in Saccharomyces cerevisiae. It is accumulated intracellularly when cells are exposed to decreased extracellular water activity. In general, increased intracellular accumulation of a solute may be caused by enhanced production, restricted dissimilation, increased retention by the plasma membrane and increased uptake from the medium. In this review, we evaluate current knowledge concerning mechanisms leading to the accumulation of glycerol in osmotically stressed cells of S. cerevisiae at the molecular and metabolic levels. An overview of glycerol metabolism in S. cerevisiae is provided.

Biological Transport↗
PubMed1995

T lymphocyte chemotaxis and skin diseases.

Recent advances in our understanding of the mechanisms of T lymphocyte motility and chemotaxis, particularly in aspects of lymphocyte-endothelial adhesion, transendothelial cell migration, and T-lymphocyte response to chemotactic gradients have contributed to our knowledge of how T lymphocytes accumulate during the initiation, the development and the control of inflammatory skin responses. In this review, we will summarize the present situation of studies on T lymphocyte adhesion and chemotaxis. The 3 major steps in T lymphocyte chemotaxis, e.g., recognition of extracellular chemotactic gradients, transduction into appropriate intracellular signals, and generation of motion, will be outlined. Skin-homing T lymphocytes, chemokines and other chemoattractants will also be discussed in relation to skin diseases.

Animals↗
PubMed2004

Cofilin 1 is revealed as an inhibitor of glucocorticoid receptor by analysis of hormone-resistant cells.

Significant knowledge about glucocorticoid signaling has accumulated, yet many aspects remain unknown. We aimed to discover novel factors involved in glucocorticoid receptor regulation that do not necessarily require direct receptor interaction. We achieved this by using a functional genetic screen: a stable cell line which cannot survive hormone treatment was engineered, randomly mutated, and selected in the presence of glucocorticoid. A hormone-resistant clone was analyzed by two-dimensional gel electrophoresis. Differentially expressed proteins were identified and tested as candidates for regulation of the glucocorticoid receptor. An unexpected candidate, cofilin 1, inhibited receptor activity. Cofilin is known to promote actin depolymerization and filament severing. Several experiments suggest that this feature of cofilin is involved in its inhibitory action. Both its actin depolymerization activity and its inhibitory action on the receptor are dependent on its phosphorylation state. Treatment of cells with a cytoskeleton-disrupting agent decreased receptor activity, as did overexpression of actin, particularly a mutant actin that does not polymerize. In addition, overexpression of cofilin and actin as well as chemical cytoskeleton disruption changed the subcellular receptor distribution and upregulated c-Jun, which could constitute the inhibitory mechanism of cofilin. In summary, cofilin represents a novel factor that can cause glucocorticoid resistance.

Actin Depolymerizing Factors↗
PubMed2000

Metabolic engineering of Saccharomyces cerevisiae.

Comprehensive knowledge regarding Saccharomyces cerevisiae has accumulated over time, and today S. cerevisiae serves as a widley used biotechnological production organism as well as a eukaryotic model system. The high transformation efficiency, in addition to the availability of the complete yeast genome sequence, has facilitated genetic manipulation of this microorganism, and new approaches are constantly being taken to metabolicially engineer this organism in order to suit specific needs. In this paper, strategies and concepts for metabolic engineering are discussed and several examples based upon selected studies involving S. cerevisiae are reviewed. The many different studies of metabolic engineering using this organism illustrate all the categories of this multidisciplinary field: extension of substrate range, improvements of producitivity and yield, elimination of byproduct formation, improvement of process performance, improvements of cellular properties, and extension of product range including heterologous protein production.

Biotechnology↗
PubMed2004

Echolocation clicks of two free-ranging, oceanic delphinids with different food preferences: false killer whales Pseudorca crassidens and Risso's dolphins Grampus griseus.

Toothed whales (Odontoceti, Cetacea) navigate and locate prey by means of active echolocation. Studies on captive animals have accumulated a large body of knowledge concerning the production, reception and processing of sound in odontocete biosonars, but there is little information about the properties and use of biosonar clicks of free-ranging animals in offshore habitats. This study presents the first source parameter estimates of biosonar clicks from two free-ranging oceanic delphinids, the opportunistically foraging Pseudorca crassidens and the cephalopod eating Grampus griseus. Pseudorca produces short duration (30 micro s), broadband (Q=2-3) signals with peak frequencies around 40 kHz, centroid frequencies of 30-70 kHz, and source levels between 201-225 dB re. 1 micro Pa (peak to peak, pp). Grampus also produces short (40 micro s), broadband (Q=2-3) signals with peak frequencies around 50 kHz, centroid frequencies of 60-90 kHz, and source levels between 202 and 222 dB re. 1 micro Pa (pp). On-axis clicks from both species had centroid frequencies in the frequency range of most sensitive hearing, and lower peak frequencies and higher source levels than reported from captive animals. It is demonstrated that sound production in these two free-ranging echolocators is dynamic, and that free-ranging animals may not always employ biosonar signals comparable to the extreme signal properties reported from captive animals in long-range detection tasks. Similarities in source parameters suggest that evolutionary factors other than prey type determine the properties of biosonar signals of the two species. Modelling shows that interspecific detection ranges of prey types differ from 80 to 300 m for Grampus and Pseudorca, respectively.

Animal Communication↗
PubMed2001

[DNA arrays: technological aspects and applications].

The Human Genome Project has allowed considerable progress in the construction of physical and genetic maps and the identification of genes involved in human sicknesses. The accelerated accumulation of biological information and knowledge is due in large part to the sequencing projects of other organisms, which in fact paved the way for the Human Genome Project. In parallel, recently developed techniques which take advantage of genomic sequences allow large scale molecular analyses resulting in the functional annotation of many of the proteins represented by these genes. This is the goal of functional genomics. These progresses are at the origin of the present revolution in biomedical research. DNA microarrays are playing a dominant role compared to the other developing technologies since they are relatively easy to make and use and are applicable to numerous scientific inquiries. They allow the simultaneous analysis of several thousands of genes in biological samples from sick or healthy tissues, at the genome or transcriptome level. The data obtained is expected to result in major advances in the health sciences. In addition to an improved understanding of the complex molecular interaction networks of healthy cells and tissues, a more precise genetic characterization of the molecular mechanisms involved in pathology should result in the identification of new therapeutic targets and the development of new medicines. The genetic profiles thus obtained should also permit the definition of new pathologic subclasses not recognizable by traditional clinical factors, as well as new markers for susceptibility to certain illnesses, and new prognostic markers or methods of predicting responses to treatment. In this article, we present the different approaches and potential applications of DNA microarray technology, in particular as applied to cancer research.

Chromosome Mapping↗
PubMed2000

[Spectrum and methods of detection of mutations in a phenylalanine hydroxylase gene from patients with phenylketonuria from the Novosibirsk region].

Phenylketonuria (PKU) is a widespread autosome recessive hereditary disease caused by a deficiency of the liver enzyme phenylalanine hydroxylase, which results in the distortion of phenylalanine metabolism and accumulation of toxic metabolites. The knowledge of molecular bases of PKU is of a high social importance as it enables phenotypic correction of the disease in the case of its early diagnostics. This disease is known to be associated with mutations in the phenylalanine hydroxylase gene, the distribution and mutation spectrum having pronounced ethnic and regional features. We studied the spectrum of mutations in the phenylalanine hydroxylase gene in a group of patients with PKU from the Novosibirsk region to reveal 10 missense point mutations, 1 mutation in the splice donor site, and 1 microdeletion. For these mutations, most widely distributed in the region, we used straightforward detection methods based on the restriction fragment length polymorphism (RFLP), artificial constructed restriction sites (ACRS) PCR, and denaturing gradient gel electrophoresis (DGGE).

Humans↗
PubMed2002

Asia-Pacific mussel watch: monitoring of butyltin contamination in coastal waters of Asian developing countries.

Butyltin compounds (BTs) including mono-, di-, and tributyltin and total tin (sigmaSn), were determined in green mussels (Perna viridis) from various Asian developing countries, such as Cambodia, China (Hong Kong and southern China), Malaysia, India, Indonesia, the Philippines, and Vietnam, to elucidate the contamination status, distribution, and possible sources and to assess the risks on aquatic organisms and humans. Butyltin compounds were detected in green mussels collected from all the sampling location investigated, suggesting widespread contamination of BTs along the coastal waters of Asian developing countries. Among butyltin derivatives, tributyltin (TBT) was the predominant compound, indicating its ongoing usage and recent exposures in Asian coastal waters. Higher concentrations of BTs were found in mussels collected at locations with intensive maritime activities, implying that the usage of TBT as a biocide in antifouling paints was a major source of BTs. In addition, relatively high concentrations of BTs were observed in mussels from aquaculture areas in Hong Kong and Malaysia, as it has been reported in Thailand. With the recent improvement in economic status in Asia, it is probable that an increase in TBT usage will occur in aquaculture. Although contamination levels were generally low in mussel samples from most of the Asian developing countries, some of those from polluted areas in Hong Kong, India, Malaysia, the Philippines, and Thailand revealed levels comparable to those in developed nations. Furthermore, the concentrations of TBT in some mussels from polluted areas exceeded the threshold for toxic effects on organisms and estimated tolerable average residue levels as seafoods for human consumption. A significant correlation was observed between the concentrations of sigmaBTs and sigmaSn in mussels, and sigmaBTs were made up mostly 100% of sigmaSn in mussels taken from locations having intensive maritime/human activities. This suggests that anthropogenic BTs represent the major source of tin accumulation in mussels. To our knowledge, this is a first comprehensive report on butyltin pollution monitoring in developing countries in the Asia-Pacific region.

Animals↗
PubMed2003

Protein p53--structure, function, and possible therapeutic implications.

Cell cycle is driven by a number of positive and negative regulatory phosphorylation and dephosphorylation events that ultimately influence the activity of transcription factors. Normal skin architecture depends on the regulation mechanisms of cell proliferation and differentiation and on apoptosis. Complex interaction of different factors in the regulation of these mechanisms, aimed at maintaining constant desquamation, is often changed in skin diseases. The main difference between normal cells and tumor cells results from discrete changes in specific genes important for cell proliferation control mechanisms and tissue homeostasis. These genes are mainly proto-oncogenes or tumor-suppressor genes, and their mutation could play a role in cell hyperproliferation and carcinogenesis. Tumor-suppressor genes normally function as a physiological barrier against clonal expansion or mutation accumulation in the genome. They also control and arrest growth of the cells that hyperproliferate due to oncogene activity. Alteration or DNA damage in tumor-suppressor genes and oncogenes are considered key events in human carcinogenesis. Tumor-suppressor protein p53 is an important transcription factor, which plays a central role in the cell cycle regulation mechanisms and cell proliferation control, and its inactivation is considered a key event in human carcinogenesis. The role of p53 protein in the cell cycle, high proportion of tumors with mutated p53 gene, and accumulation of significant amount of knowledge on molecular biology of this protein make this molecule especially attractive for development of new therapeutic approaches. Main strategies for development of new antineoplastic therapies are based on "wild-type" p53 protein acting as a tumor suppressor, selective apoptosis inductor, and a protein able to arrest cell cycle.

Genes, p53↗
PubMed1991

Application of ecopathological methods to the investigation of health problems on farms.

Application of the techniques of ecopathology to the investigation of health problems on farms has allowed a specific methodology for the study of enzootic diseases of multiple aetiology, dominant under intensive husbandry, to be developed. New knowledge about such diseases has accumulated for various species of animals. Finally, a procedure for regulating and managing the health risks of livestock farming is proposed.

Agriculture↗
PubMed1991

Setting the optimal erythrocyte protoporphyrin screening decision threshold for lead poisoning: a decision analytic approach.

Erythrocyte protoporphyrin (EP) was introduced in the 1970s as an inexpensive screening test for lead poisoning. As greater knowledge of lead poisoning has accumulated, the recommended EP level at which further evaluation for lead poisoning should be initiated has been lowered from greater than or equal to 50 micrograms/dL to greater than or equal to 35 micrograms/dL. The purpose of this study was to evaluate the utility of this EP threshold. A receiver operator characteristic curve was constructed to assess the relationship between the true-positive rate and false-positive rate of EP at various decision thresholds. The receiver operator characteristic curve was constructed with data from the second National Health and Nutrition Examination Survey from 1976 to 1980, which included 2673 children 6 years of age or younger who had both blood lead and EP level determinations. Decision analysis was then used to determine the optimal EP decision threshold for detecting a blood lead level greater than or equal to 25 micrograms/dL. The receiver operator characteristic curve demonstrated that EP is a poor predictor of a blood lead level greater than or equal to 25 micrograms/dL. At the currently recommended EP decision threshold of 35 micrograms/dL, the true-positive rates and false-positive rates of EP are 0.23 and 0.04, respectively. As a result of the inadequate performance of EP screening for lead poisoning, when the prevalence of lead poisoning is greater than 8%, there is no EP decision threshold that optimizes the relationship between the cost of screening normal children and the benefit of detecting lead-poisoned children. Erythrocyte protoporphyrin measurement is not sufficiently sensitive to be recommended uniformly as a screening test for lead poisoning.

Child↗
PubMed1990

The molecular genetics of retinoblastoma.

Retinoblastoma is a potentially hereditary cancer. Refinement of the genetic and epidemiological analysis of the disease has uncovered two distinct classes of retinoblastoma. Sporadic retinoblastoma is generally unilateral and unifocal, and is diagnosed at the late age of about two years. A few of these sporadic cases are probably due to a germ cell mutation inherited from a parent and hence can be classified as hereditary. Familial retinoblastoma is generally diagnosed at an earlier age, at 11 months, and is typically bilateral and/or multifocal. These observations have been incorporated into a 'two hit' mutational inactivation hypothesis of the origin of retinoblastoma. The molecular cloning and characterization of a candidate retinoblastoma susceptibility gene and its gene product has allowed a critical testing of this hypothesis. All of the predications of the model have been confirmed by experiment. These include inheritance of one mutated retinoblastoma susceptibility (RB) allele as the origin of hereditary retinoblastoma, subsequent loss of the remaining allele upon the genesis of the tumour, the involvement of the same RB gene in both sporadic and hereditary retinoblastoma, the somatic mutation of both RB alleles in sporadic retinoblastoma, the lack of evidence for expression of a normal RB gene product in any retinoblastoma yet examined, the inactivational nature of RB mutations and the recessiveness of these mutated alleles. The RB gene also exhibits suppression of neoplastic properties when introduced into retinoblastoma cells and also into some other tumour cells. These results mutually reinforce the two hit inactivation hypothesis as well as the cloned gene's correct identification as the retinoblastoma susceptibility locus. The confirmation of this hypothesis is, therefore, nearing completion. The definitive proof is achievable with the advent of chimeric mouse technology, which will allow construction of mice with one or both RB alleles that have been inactivated by mutation. Analysis of such mice may allow us to determine if inactivation of both RB alleles is necessary and sufficient for the development of retinoblastoma and possibly other tumour types. The molecular isolation of the RB gene is an important achievement in research on cancer. For the first time, it has become possible to examine, at the molecular level, genes which suppress the tumorigenicity of cancer cells. Analysis of such cloned genes should yield insight into mechanisms of oncogenesis, gene regulation and cellular differentiation complementary to the knowledge which has long been accumulating from the study of oncogenes.

Chromosome Mapping↗
PubMed1986

The pathologic findings of the fetal membranes in very prolonged amniotic fluid leakage.

We examined the fetal membranes in five patients with prolonged amniotic fluid leakage. Four patients had a clinical history of fluid leakage of at least six weeks' duration, while, in the fifth patient, prolonged leakage was only an inferred diagnosis. Four of the infants died within the first two days of life, while one infant survived. The pathologic findings were varied. Two cases showed, to our knowledge, a previously unreported subchorionic accumulation of squames, which were presumably from cells that were shed into amniotic fluid. One other case showed a subchorionic foreign-body reaction. The two remaining cases showed only necrosis and hemorrhage.

Amnion↗
PubMed1993

[A case of interferon-alpha-induced pneumonitis].

We report a case of interferon-alpha-induced pneumonitis. A 61-year-old man was diagnosed as having recurrence of renal cell carcinoma and treated with 3 x 10(6) unit of interferon-alpha daily for 8 weeks. On the 55th injection, he presented with a high fever and mild dyspnea, and his chest CT films revealed diffuse reticulonodular shadows in both lung fields. We suspected interstitial pneumonitis due to interferon-alpha, and started steroid therapy. He showed rapid improvement of symptoms and diffusing capacity, and the pulmonary infiltrates in his chest CT were markedly reduced. Transbronchial lung biopsy (TBLB) revealed slightly thickened alveolar walls and small granulomatous-like lesions. These granulomatous-like lesions showed marked accumulation of macrophages. To our knowledge, this is the first report of interferon-alpha-induced pulmonary injury in Japan.

Carcinoma, Renal Cell↗
PubMed2000

Fuel selection in human skeletal muscle in insulin resistance: a reexamination.

For many years, the Randle glucose fatty acid cycle has been invoked to explain insulin resistance in skeletal muscle of patients with type 2 diabetes or obesity. Increased fat oxidation was hypothesized to reduce glucose metabolism. The results of a number of investigations have shown that artificially increasing fat oxidation by provision of excess lipid does decrease glucose oxidation in the whole body. However, results obtained with rodent or human systems that more directly examined muscle fuel selection have found that skeletal muscle in insulin resistance is accompanied by increased, rather than decreased, muscle glucose oxidation under basal conditions and decreased glucose oxidation under insulin-stimulated circumstances, producing a state of "metabolic inflexibility." Such a situation could contribute to the accumulation of triglyceride within the myocyte, as has been observed in insulin resistance. Recent knowledge of insulin receptor signaling indicates that the accumulation of lipid products in muscle can interfere with insulin signaling and produce insulin resistance. Therefore, although the Randle cycle is a valid physiological principle, it may not explain insulin resistance in skeletal muscle.

Animals↗
PubMed2006

Human blood monitoring program in Japan: contamination and bioaccumulation of persistent organochlorines in Japanese residents.

Concentrations of persistent organochlorines (OCs)-such as polychlorinated biphenyls (PCBs), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene, and tris(4-chlorophenyl)methane [TCPMe]-were determined in plasma samples from residents of three sub-metropolitan locations in Japan (Miyako, Saku, and Tottori) for the purpose of studying the geographic variation and specific accumulation of OCs. Residue concentrations of PCBs and DDTs were the highest in samples collected in Saku (400 and 370 ng/g lipid wt, respectively) whereas samples from Miyako contained greater CHL residues (70 ng/g lipid wt) than those from the other two locations. This contamination pattern reflects the historic use of OCs in each area. For the first time, tris (4-chlorophenyl) methane (TCPMe) concentrations were detected in most of the plasma sample analyzed. Concentrations of TCPMe which ranged from <0.1 to 8.1 ng/g lipid wt eight, were lower than those previouly reported in other human tissue. Larger geographic differences in OC accumulation were observed for PCBs and CHLs, whereas DDTs and HCHs exhibited little variability. PCB concentrations in samples from Saku residents were higher than those from residents of countries in the circumpolar Arctic region but lower than those reported for some populations in the United States and Western European countries. Interestingly, CHL residue concentrations in human blood from Japan are among the highest values reported for the countries examined, suggesting continued increased exposure to CHLs of the Japanese population. Time-trend analysis of CHLs in human blood samples from Miyako (Okinawa prefecture) showed that CHL residues have decreased substantially during the last decade, indicating the effect of the official ban of CHLs in 1986 in Japan. Isomer-specific analysis of PCBs revealed lower proportions of higher chlorinated congeners such as hepta- and octachlorobiphenyls in women than in men, suggesting the possibility of preferential elimination of higher chlorinated biphenyls in women. The difference in sex-dependent accumulation of OC compounds in healthy and ill persons was suggested. To our knowledge, this is the first report on the specific accumulation of persistent QCs, including TCPMe, in human blood samples from Japan.

Adult↗