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At least 1,783 records · Page 99Linked to original sources
PubMed1985

Altered Cro repressors from engineered mutagenesis of a synthetic cro gene.

A portion of the gene coding for the Cro repressor protein of bacteriophage lambda has been chemically synthesized, incorporating base pair changes that generate restriction endonuclease sites without altering the amino acid coding sequence. These restriction endonuclease sites were used to remove small segments of the synthetic cro gene and the segments were replaced with duplexes carrying desired mutations. Altered Cro proteins produced by mutants constructed in this manner were then assayed for binding to lambda operator OR3 in vivo. Mutations directed into the region of the cro gene encoding the alpha-3 helix produced altered Cro proteins with a range of affinities for operator DNA. These changes suggest which amino acids play an important role in Cro-OR3 complex formation.

Bacteriophage lambda↗
PubMed1991

Construction of interleukin-1 alpha mutants using unequal contamination of synthetic oligonucleotides.

Proteins without readily available three-dimensional structural data present a difficult problem in the exploration of structure/function relationships. Saturation mutagenesis using contaminated oligonucleotides can identify potentially interesting regions of such a protein. This technique, in which synthesized oligonucleotides contain low-level base substitutions, allows random mutations to be placed throughout a gene sequence. Using double-stranded cassettes, a region of the human interleukin-1 alpha gene has been altered using such mutagenic oligonucleotides. However, instead of contaminating both strands of the gene sequence at the same level, each strand of the insert was contaminated at a different level. Several recombinants were sequenced and the effects of the mutations on the activity of the proteins were examined. Contaminating the two oligonucleotides at different levels produced a significantly different distribution of nucleotide changes from that seen if both strands were contaminated at the same level. The observed distribution followed the average of the distributions for each of the two contamination levels. This resulted in roughly equal frequencies of 1 to 5 nucleotide changes per clone with very few clones containing the wild-type nucleotide sequence. This helped overcome the redundancy in the genetic code, resulting in a high frequency of amino acid changes, and allowed changes at every amino acid to be sampled in a small number of mutants. This procedure can allow a gene sequence to be screened rapidly by removing most wild-type sequences from analysis while making sure that there are many amino acid changes in the resultant mutants.

Amino Acid Sequence↗
PubMed2000

Home care and hospice ethics: using the code for nurses as a guide.

In today's rapidly changing healthcare environment, home care and hospice nurses face complex ethical dilemmas. Many result from situations with two opposing, but equally reasonable, solutions. Understanding how and why ethical dilemmas arise helps nurses recognize the potential for an ethical dilemma and formulate justifiable solutions. This article, the first of a new ethics column in Home Healthcare Nurse, sets the foundation for the nurse's understanding of these dilemmas by applying the American Nurses Association's Code for Nurses with Interpretive Statements to real case studies.

Confidentiality↗
PubMed2003

Effects of habitat fragmentation and changes of dispersal behaviour after a recent population decline on the genetic variability of noncoding and coding DNA of a monogamous Malagasy rodent.

While interactions among demography, behaviour and genetic structure are well-documented for neutral genetic markers, the role of these parameters and the effects of genetic drift and selection are considerably less well understood in functional genes, such as the major histocompatibility complex (MHC). In this study, the consequences of habitat fragmentation and the effects of a current population decline on noncoding (mitochondrial DNA) and two coding MHC loci (DQA, DRB) with different functional importance were investigated in the small remnant subdivided population of the endangered Malagasy giant jumping rat (Hypogeomys antimena). Both neutral and selective markers revealed a significant genetic differentiation between the two remnant subpopulations. The FST values were much lower in the MHC DQA and DRB genes than in the mitochondrial data. The MHC DRB loci display the effects of both balancing selection (high sequence diversity, four times higher nonsynonymous than synonymous substitutions in the functionally important antigen-binding site positions, twice the average heterozygosity of individual amino acids at the positions identified as part of the antigen-binding site (ABS) than those outside the ABS and nonselective forces including genetic drift. Simultaneously with a current population decline offspring reduced their dispersal distances. No substantial effects were detected within the first 6 years of reduced gene flow in either mitochondrial or MHC markers.

Animals↗
PubMed1983

Modifications of dynamic and static behavior by small-length perturbations in crayfish stretch receptor organs.

To investigate whether static and dynamic sensitivities of slowly and rapidly adapting stretch receptor organs (SAO and RAO, respectively) or crayfish are different when perturbed compared with those in conventional laboratory experiments, receptors were submitted to ramplike length changes of different velocities separated by long-duration, constant lengths of different values. They were perturbed at random by fast, small-amplitude length variations called "jitter." First-order afferent discharges were recorded extracellularly. Quantifications involved the separate estimation of static and dynamic response components. In the SAO, jitter (1) augmented the static sensitivity, (2) decreased the dynamic sensitivity, (3) simplified response profiles by decreasing nonlinearities and increasing transduction fidelity in terms of coding length. In the RAO, jitter (1) changed the behavior from phasic to tonic with length sensitivity, (2) decreased the dynamic sensitivity to values close to those of the unperturbed SAO, (3) increased transduction fidelity for stimulus length and decreased nonlinearities. Perturbation effects suggest that differences between SAO and RAO are more quantitative than qualitative. Moreover, they have general implications and are relevant to other mechanoreceptors at other levels in the CNS.

Animals↗
PubMed1988

Changes in telomere length associated with antigenic variation in Trypanosoma brucei.

In the IsTaR 1 serodeme, we have identified variant surface glycoprotein (VSG) genes in nine different telomeric sites. We have measured the distance from the 3' end of these VSG genes to the end of the chromosome (the 'telomere length') in 20 variant antigen types (VATs) of the serodeme. Analyses of the changes in telomere length during 19 antigenic switches involving eight telomeric sites indicate a median increase in telomere length of 0.6 kilobase pairs during each switch. This may be accounted for by the 6-10 bp increase in telomere length per generation associated with DNA replication described by others. The changes in telomere lengths do not form a normal distribution since a substantial fraction show unusually large increases in telomere length or decreases in telomere length during an antigenic switch. These changes are probably caused by recombinations 3' to the VSG gene. No significant differences were detected in the behavior of telomeres at each of the eight different telomeric sites, nor were changes in telomere lengths significantly different between different antigenic switches. However, it was found that those telomeres where transcription was activated during the antigenic switch showed a significantly greater increase in telomere length than those telomeres not involved in regulation of VSG gene expression. Conversely, there was a strong correlation between transcriptional inactivation of a telomeric expression site and a decrease in telomere length. These findings suggest that processes (possibly genomic recombinations) 3' to the VSG gene coding region may be associated with a change in the transcriptional status of the VSG gene.

Animals↗
PubMed2002

Resource-based relative value units: a primer for academic family physicians.

The Resource-based Relative Value Scale (RBRVS) is the prevailing model used to reimburse physician services today. Based on empirical research, relative value units (RVUs) quantify the relative work, practice expense, and malpractice costs for specific physician services to appropriately establish payment. The fee schedule, implemented by the Health Care Financing Administration in 1992, dramatically affected physician reimbursement, with the goal of correcting disparities across disciplines. In the first 6 years, Medicare payments to family physicians increased by 36%, while payments to specialists decreased by as much as 18%. Recent changes include new practice expense estimates and adjustment of payment based on facility type. The impact of RVUs is even more widespread as many private payers use the fee schedule to set payment rates and as RVUs become the yardstick for physician productivity measures. Despite the initial successes, the ability of RVUs to capture the work done by primary care providers is still limited. Primary care services today are not as easily quantified as surgical procedures, and coding limitations hinder documentation of services. Rapid changes in health care make comparisons to work done 2 decades ago difficult. Understanding the strengths and limitations of RVUs as they apply to family physicians is fundamental to safeguarding the role of primary care.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1989

[The electrocardiogram of patients with mild craniocerebral trauma].

The authors analyze 236 electrocardiograms in 1343 patients of young and middle age with mild head injuries. The Minnesota code was used in the analysis of the electrocardiograms. It was found that mild craniocerebral trauma causes diffuse changes in the cardiac muscle. The character and degree of these changes are not homogeneous. The dynamics of the number of coded signs and their ratios were used to evaluate the functional state of the vegetative nervous system.

Adult↗
PubMed1995

Congenital hypomyelination neuropathy: decreased expression of the P2 protein in peripheral nerve with normal DNA sequence of the coding region.

Congenital hypomyelination neuropathy (Lyon type) is characterized by a non-progressive clinical course and a histopathological formation of atypical onion-bulb. We have studied the immunohistochemical expression of the major peripheral myelin proteins including P0 protein, myelin basic protein (MBP) and P2 protein in three such patients. No significant difference was observed between the patients and the controls, as to the P0 and MBP staining. In contrast, P2 protein antiserum scarcely stained the patients' nerve fibers except for a few scattered adequately myelinated fibers. Assuming the pathogenetic contribution of the extremely decreased P2 protein to the disease, we investigated P2 protein gene by sequencing all coding regions but failed to detect any change in the nucleotide sequence. Further investigation including the analysis of promoter region of P2 protein gene is needed to elucidate the mechanism of congenital hypomyelination neuropathy.

Base Sequence↗
PubMed2006

A comprehensive catalog of human KRAB-associated zinc finger genes: insights into the evolutionary history of a large family of transcriptional repressors.

Krüppel-type zinc finger (ZNF) motifs are prevalent components of transcription factor proteins in all eukaryotes. KRAB-ZNF proteins, in which a potent repressor domain is attached to a tandem array of DNA-binding zinc-finger motifs, are specific to tetrapod vertebrates and represent the largest class of ZNF proteins in mammals. To define the full repertoire of human KRAB-ZNF proteins, we searched the genome sequence for key motifs and then constructed and manually curated gene models incorporating those sequences. The resulting gene catalog contains 423 KRAB-ZNF protein-coding loci, yielding alternative transcripts that altogether predict at least 742 structurally distinct proteins. Active rounds of segmental duplication, involving single genes or larger regions and including both tandem and distributed duplication events, have driven the expansion of this mammalian gene family. Comparisons between the human genes and ZNF loci mined from the draft mouse, dog, and chimpanzee genomes not only identified 103 KRAB-ZNF genes that are conserved in mammals but also highlighted a substantial level of lineage-specific change; at least 136 KRAB-ZNF coding genes are primate specific, including many recent duplicates. KRAB-ZNF genes are widely expressed and clustered genes are typically not coregulated, indicating that paralogs have evolved to fill roles in many different biological processes. To facilitate further study, we have developed a Web-based public resource with access to gene models, sequences, and other data, including visualization tools to provide genomic context and interaction with other public data sets.

Computational Biology↗
PubMed2000

Isolating the neural mechanisms of age-related changes in human working memory.

Working memory (WM), the process by which information is coded into memory, actively maintained and subsequently retrieved, declines with age. To test the hypothesis that age-related changes in prefrontal cortex (PFC) may mediate this WM decline, we used functional MRI to investigate age differences in PFC activity during separate WM task components (encoding, maintenance, retrieval). We found greater PFC activity in younger than older adults only in dorsolateral PFC during memory retrieval. Fast younger subjects showed less dorsolateral PFC activation during retrieval than slow younger subjects, whereas older adults showed the opposite pattern. Thus age-related changes in dorsolateral PFC and not ventrolateral PFC account for WM decline with normal aging.

Adult↗
PubMed2002

Progression of keratoconus assessed by fourier analysis of videokeratography data.

OBJECTIVE: To quantitatively document changes in corneal refractive parameters in relation to the progression of keratoconus over years. DESIGN: Retrospective observational case series. PARTICIPANTS: Eighty-five eyes of 64 patients with keratoconus who had undergone videokeratography examinations at least twice with an interval of 1 year or longer between each examination. METHODS: By means of Fourier series harmonic analysis, topography data were decomposed into spherical component, regular astigmatism, decentration component, and higher order irregularity. MAIN OUTCOME MEASURES: Change rate of each parameter per year was calculated by use of the least squares method. RESULTS: All four refractive parameters were significantly larger in the keratoconic eyes than in the age-matched normal controls (P < 0.001, Student's t test). The yearly rate of change was significantly positive for spherical component (P = 0.008) and higher order irregular astigmatism (P = 0.015) but not for the regular astigmatism and decentration component. In eyes that showed apparent progression on color-coded maps, spherical component showed a significantly positive change rate per year (P = 0.002), but other parameters did not. In eyes without apparent progression, the yearly change rate of higher order irregular astigmatism was significantly larger than zero (P = 0.049). CONCLUSIONS: Keratoconus progression over years was quantitatively described. It was indicated that spherical equivalent is a manifest indicator for the apparent progression of keratoconus, and irregular astigmatism increases along with the natural course of the disease.

Adolescent↗
PubMed1995

Under-reporting of suicide in an Irish county.

It is clearly important to have accurate figures on suicides, but official statistics may not always reflect the true numbers of suicides. In this paper, the authors describe how the files of all deaths reported to the coroners of County Mayo, Ireland, for the period 1978-1992 were examined. Those deaths considered to be suicide by the authors were abstracted. Of these deaths, it was found that 7.3% had not been officially registered. The remainder were coded to three different categories in official returns: suicide, undetermined, and accident. In all, 35% of deaths were, in the author's opinion, miscoded or unregistered. The authors compared these three groups on a number of demographic variables with the expectation that if suicide deaths were being miscoded to undetermined and accident, no significant difference would be found between the three groups. This was found to be the case other than for mode of death. The authors found the greatest miscoding was for deaths due to drowning. The authors recommended that changes be made in the reporting and coding system for suicide deaths in Ireland.

Accidents↗
PubMedDate not supplied

Improving the sensitivity and specificity of the abbreviated injury scale coding system.

The Abbreviated Injury Scale with Epidemiologic Modifications (AIS 85-EM) was developed to make it possible to code information about anatomic injury types and locations that, although generally available from medical records, is not codable under the standard Abbreviated Injury Scale, published by the American Association for Automotive Medicine in 1985 (AIS 85). In a population-based sample of 3,223 motor vehicle trauma cases, 68 percent of the patients had one or more injuries that were coded to the AIS 85 body region nonspecific category external. When the same patients' injuries were coded using the AIS 85-EM coding procedure, only 15 percent of the patients had injuries that could not be coded to a specific body region. With AIS 85-EM, the proportion of codable head injury cases increased from 16 percent to 37 percent, thereby improving the potential for identifying cases with head and threshold brain injury. The data suggest that body region coding of all injuries is necessary to draw valid and reliable conclusions about changes in injury patterns and their sequelae. The increased specificity of body region coding improves assessments of the efficacy of injury intervention strategies and countermeasure programs using epidemiologic methodology.

Accidents, Traffic↗
PubMed2005

Inhibited cell growth and protein functional changes from an editing-defective tRNA synthetase.

The genetic code is established in aminoacylation reactions catalyzed by aminoacyl-tRNA synthetases. Many aminoacyl-tRNA synthetases require an additional domain for editing, to correct errors made by the catalytic domain. A nonfunctional editing domain results in an ambiguous genetic code, where a single codon is not translated as a specific amino acid but rather as a statistical distribution of amino acids. Here, wide-ranging consequences of genetic code ambiguity in Escherichia coli were investigated with an editing-defective isoleucyl-tRNA synthetase. Ambiguity retarded cell growth at most temperatures in rich and minimal media. These growth rate differences were seen regardless of the carbon source. Inclusion of an amino acid analogue that is misactivated (and not cleared) diminished growth rate by up to 100-fold relative to an isogenic strain with normal editing function. Experiments with target-specific antibiotics for ribosomes, DNA replication, and cell wall biosynthesis, in conjunction with measurements of mutation frequencies, were consistent with global changes in protein function caused by errors of translation and not editing-induced mutational errors. Thus, a single defective editing domain caused translationally generated global effects on protein functions that, in turn, provide powerful selective pressures for maintenance of editing by aminoacyl-tRNA synthetases.

Amino Acyl-tRNA Synthetases↗
PubMed2006

A code of professional conduct for members.

In light of new legislation and changing practice, together with the impending legal status of members who practise clinical photography and/or clinical videography, the Institute of Medical Illustrators (IMI) has revised and brought together A Code of Responsible Practice and its Code of Conduct. The new document, A Code of Professional Conduct for Members, details the standards required to maintain professional practice. Within the text, the Code refers to members, and where specifically appropriate, to clinical photographers. The title, 'clinical photographer', is used where the code applies to members practising clinical photography and/or videography.

Codes of Ethics↗
PubMed2003

A novel termination codon mutation of the WAS gene in a Thai family with Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by microthrombocytopenia, eczema, immunodeficiency, and susceptibility to lymphoid malignancy. Loss-of-function mutations in WAS gene have been identified to cause disorders with platelet defects including WAS and X-linked thrombocytopenia. Mutations anticipated to yield truncated or no protein have been associated with the more severe presentations of WAS. Activating mutations in WAS gene result in an entirely different phenotype, an X-linked severe congenital neutropenia. We describe a Thai family with classic WAS. The proband, a one-year-old boy presented with recurrent mucous bloody diarrhea, recurrent otitis media, chronic eczema, thrombocytopenia, and small platelet sizes. The patient's older brother who also had persistent thrombocytopenia died at the age of seven months from severe pneumonia. Immunoblot analysis demonstrated that the proband's cells lacked WAS protein expression. Mutation analysis of the proband and his mother for the entire coding region of WAS identified a novel type of mutation, a termination codon mutation, X503R. The change is expected to result in an elongated mRNA that would code for a WASP of 581 amino acid residues instead of the normal 502 residues. Because of the absence of WASP expression, we speculate that the termination codon mutation causes reduced mRNA stability. Our findings supported that WAS mutations resulted in no protein are associated with a severe phenotype of WAS.

Codon, Terminator↗
PubMed2005

Sex-contingent face after-effects suggest distinct neural populations code male and female faces.

Exposure to faces biases perceptions of subsequently viewed faces. Faces similar to those seen previously are judged more normal and attractive than they were prior to exposure. Here we show sex-contingent after-effects following adaptation to eye-spacing (experiment 1), facial identity (experiment 2) and masculinity (experiment 3). Viewing faces of one sex with increased eye-spacing and faces of the other sex with decreased eye-spacing simultaneously induced opposite after-effects for male and female faces (assessed by normality judgments). Viewing faces transformed in identity or masculinity increased preferences for novel faces with characteristics similar to those viewed only when the sex of the faces presented in the adaptation phase and in post-adaptation preference tests were congruent. Because after-effects reflect changes in responses of neural populations that code faces, our findings indicate that distinct neural populations code male and female faces.

Adult↗