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PubMed1975

The dose-response relationship for ethyl methanesulfonate-induced mutations at the hypoxanthine-guanine phosphoribosyl transferase locus in Chinese hamster ovary cells.

The frequency of ethyl methanesulfonate (EMS)-induced mutations to 6-thioguanine resistance in a Chinese hamster ovary cells clone K1-BH4 was studied at many EMS doses including the minimally lethal range (0-100 microng/ml) as well as the exponential killing portion (100-800 microng/ml) of the survival curve. The mutation frequency increases approximately in proportion with increasing EMS concentration at a fixed treatment time. The pooled data for the observed mutation frequency, f(X), as a function of EMS dose X, is adequately described by a linear function f(X)=10(-6)(8.73+3.45 X), where 0 less than or equal to X less than or equal to 800 microng/ml. One interpretation of the linear dose-response is that, as a result of EMS treatment, ethylation of cellular constituents occurs, which is directly responsible for the mutation. Biochemical analyses demonstrate that most of the randomly isolated 6-thioguanine-resistant variants possess a highly reduced or undetectable level of HGPRT activity suggesting that the EMS-induced mutations to 6-thioguanine resistance affect primarily, if not exclusively, the HGPRT locus.

Animals↗
PubMed2005

HPV16 E2 gene disruption and polymorphisms of E2 and LCR: some significant associations with cervical cancer in Indian women.

OBJECTIVES: We evaluated the status of the HPV16 E2 gene (disrupted or intact), nucleotide sequence alterations within intact E2 genes and LCR of HPV16 isolates in a group of CaCx cases (invasive squamous cell carcinomas, n = 81) and population controls (normal cervical scrapes, n = 27) from Indian women. METHODS: E2 disruption was detected by amplifying the entire E2 gene with single set of primers, while overlapping primers were used to determine if any particular region got selectively disrupted. Nucleotide variations in E2 and LCR were analyzed by PCR amplification followed by bi-directional sequencing. The associations between the viral factors and CaCx were analyzed using Fisher's Exact or Chi-squared test and interpreted as OR (95% CI) and P values. RESULTS: E2 disruption was significantly higher among the cases [3.38 (1.07-10.72); P = 0.02], which was maximum in the region between nucleotides 3650 and 3872 (DNA-binding region). The European (E) variant was found to be the prevalent subgroup (87.76% among cases and 96.30% among the controls), and the remaining samples were Asian-American variants. Among the E subgroup, variation at position 7450 (T > C) within the E2-binding site-IV was found to be significantly higher among the E2 undisrupted cases (21/37; 56.76%), compared to controls (5/18; 27.78%) [3.41 (1.01-11.55); P = 0.03]. CONCLUSIONS: Besides HPV16 E2 disruption, LCR 7450T > C variation within undisrupted E2 of E subgroup appears to be a major factor contributing to the risk of CaCx development in Indian women. Furthermore, polymorphisms in the E2 gene of HPV16 may not be significant for disease risk.

Adult↗
PubMed1999

Analysis of E-cadherin in diffuse-type gastric cancer using a mutation-specific monoclonal antibody.

In-frame deletions from the E-cadherin mRNA, coding for a homophilic cell adhesion molecule, are characteristic for diffuse-type gastric carcinomas. Using immunohistochemical analysis the mutant form cannot be distinguished from normal E-cadherin, making results difficult to interpret. In this study, a rat monoclonal antibody, designated E-cad delta 9-1, was generated against a peptide spanning the fusion junction region between exons 8 and 10. This new epitope is present in an E-cadherin variant that lacks exon 9 from the mRNA due to different splice-site gene mutations. Using Western blotting and immunohistochemistry of E-cadherin-transfected cells, we demonstrate that E-cad delta 9-1 specifically reacts with E-cadherin lacking exon 9 but not with the wild-type protein. No immunoreactivity was observed in 31 nontumorous and embryonal tissues analyzed. In gastric carcinoma specimens known to express mutant E-cadherin mRNA lacking exon 9, E-cad delta 9-1 targets exclusively tumor cells in routine formalin-fixed and paraffin-embedded material from biopsies, primary tumors, and lymph node metastases. In a retrospective series of 172 diffuse-type gastric carcinomas expressing E-cadherin, E-cad delta 9-1 reacted with 22 tumors (13%). This new tumor marker-monoclonal antibody system could open novel avenues for selective diagnosis and specific therapy of a subgroup of diffuse-type gastric cancer patients.

Animals↗
PubMed2003

Analysis of common mutations in the galactose-1-phosphate uridyl transferase gene: new assays to increase the sensitivity and specificity of newborn screening for galactosemia.

Classical galactosemia is a genetic disease caused by mutations in the galactose-1-phosphate uridyl transferase (GALT) gene. Prospective newborn screening for galactosemia is routine and utilizes the universally collected newborn dried blood specimen on filter paper. Screening for galactosemia is achieved through analysis of total galactose (galactose and galactose-1-phosphate) and/or determining the activity of the GALT enzyme. While this approach is effective, environmental factors and the high frequency of the Duarte D2 mutation (N314D) does lead to false positive results. Using DNA derived from the original newborn dried blood specimen and Light Cycler technology a panel of five assays able to detect the four most frequently encountered classical galactosemia alleles (Q188R, S135L, K285N, and L195P) and the N314D Duarte variant mutation are described. The five assays are performed simultaneously using common conditions. Including DNA preparation, set-up, amplification, and analysis the genotype data for all five loci is obtained in less than 2 hours. The assays are easily interpreted and amenable to high-throughput newborn screening. Mutational analysis is useful to reduce false positive results, differentiate D/G mixed heterozygotes from classical galactosemia, and to clearly identify a very high percentage of those affected by classical galactosemia.

Base Sequence↗
PubMed1999

Is there a universal need for positive self-regard?

It is assumed that people seek positive self-regard; that is, they are motivated to possess, enhance, and maintain positive self-views. The cross-cultural generalizability of such motivations was addressed by examining Japanese culture. Anthropological, sociological, and psychological analyses revealed that many elements of Japanese culture are incongruent with such motivations. Moreover, the empirical literature provides scant evidence for a need for positive self-regard among Japanese and indicates that a self-critical focus is more characteristic of Japanese. It is argued that the need for self-regard must be culturally variant because the constructions of self and regard themselves differ across cultures. The need for positive self-regard, as it is currently conceptualized, is not a universal, but rather is rooted in significant aspects of North American culture. Conventional interpretations of positive self-regard are too narrow to encompass the Japanese experience.

Cultural Characteristics↗
PubMed2003

Analysis of polymorphisms affecting immune complex handling in systemic lupus erythematosus.

OBJECTIVES: Systemic lupus erythematosus (SLE) is a polygenic disorder of dysregulated inflammation. Numerous specific candidate genes have been identified and most relate to the handling of immune complexes or antigen presentation. This is consistent with the classic finding of immune complex deposition in affected end organs. We wished to examine combinatorial effects of polymorphic variants of genes involved in immune complex clearance in susceptibility to lupus. METHODS: This study examined the occurrence of polymorphisms in genes which encode proteins known to be involved in immune complex handling and clearance. Each polymorphic variant of a complement protein (C2, mannose binding protein and C4), complement receptor (CR1) or Fc receptor (FcgammaRIIA and FcgammaRIIIA) gene is known to affect function adversely. One hundred and sixty SLE patients and 212 control subjects were genotyped using polymerase chain reaction methods. RESULTS: We found an increasing association of SLE with increasing numbers of gene defects. Combinations of severe defects in FcgammaRIIA and FcgammaRIIIA were particularly deleterious for both African American and Caucasian patients, even though only one defective variant was individually statistically significantly associated with SLE. CONCLUSIONS: The results of the study suggest that genes may interact in ways that either synergize or modify the effect of a single genetic effect and imply that association studies must be interpreted within the genetic background of the populations.

Antigen-Antibody Complex↗
PubMedDate not supplied

A stochastic interpretation of thallium myocardial perfusion scintigraphy.

A method is presented for the quantitative interpretation of thallium-201 myocardial perfusion studies. The data are planar images collected immediately following the stress injection, and 4 to 6 hours later. Data analysis consists of preprocessing, including thresholding of the original data, and data reduction using a variant of the circumferential profile methods. The profiles are subdivided into segments, and for each segment the difference between the norm and the actual data is computed. This difference is a quantitative symptom, whose size is assumed to be related to the probability of having the disease. The relationship between the size of the symptom in each of nine segments (three segments/view in three views) and the probability of disease is expressed in a table in which for 30 diseases (combinations of vascular lesions) the sensitivity for each of the nine symptoms is described as a Gaussian function whose average and standard deviation are computed from previous validated cases. Using an arbitrary prevalence, the post-testing probability can then be computed using Bayes' formula sequentially. The sensitivities, however, are not expressed as a binary function of the presence or absence of a symptom, but as a distribution function defined by experience. The method is sensitive for the detection of isolated left anterior descending disease (100%) and triple vessel disease (96%). When specific combinations of vascular lesions are recognized the specificity increases from 79% (when unspecified abnormalities are recognized) to 87% when left anterior descending disease or triple vessel disease is recognized.(ABSTRACT TRUNCATED AT 250 WORDS)

Bayes Theorem↗
PubMed1998

Peeling skin syndrome with hair changes.

A 13-year-old boy with typical peeling skin syndrome (PSS) is described. The clinical picture corresponded to the inflammatory variant of PSS (type B). In addition, the patient had gross and microscopic hair anomalies such as trichorrhexis invaginata-like changes, irregular hair shaft torsions and moniliform hair shaft diameter reductions. The observed dysmorphic hair changes are discussed and interpreted as being an integral component of the dermatosis in this case. To the best of our knowledge, such hair anomalies have not yet been described in PSS.

Adolescent↗
PubMed2002

Mutation detection in the duplicated region of the polycystic kidney disease 1 (PKD1) gene in PKD1-linked Australian families.

Screening for disease-causing mutations in the duplicated region of the PKD1 gene was performed in 17 unrelated Australian individuals with PKD1-linked autosomal dominant polycystic kidney disease. Exons 2-21 and 23-34 were assayed using PKD1-specific PCR amplification and direct sequencing. We have identified 12 novel probably pathogenic DNA variants, including five truncating mutations (Q563X, c.5105delAT, c.5159delG, S2269X, c.9847delC), two in-frame deletions (c.7472del3, c.9292del39), and two splice-site mutations (IVS14+1G>C, IVS16+1G>T). Three of the mutations (G381C, Y2185D, G2785D) were predicted to lead to the replacement of conserved amino acid residues, with ensuing changes in protein conformation. Defects in the duplicated region of PKD1 thus account for 63% of our patients. Together with the previously detected mutations (Q4041X, R4227P) in the 3 region of the gene, the study has achieved an overall mutation detection rate of 74%. In addition, we have detected 31 variants (nine novel and 22 previously published) that did not segregate with the disease and were considered to be neutral polymorphisms. Three of the nine novel polymorphisms were missense mutations with a predicted effect on protein conformation, emphasizing the problems of interpretation in PKD1 mutation screening.

Amino Acid Sequence↗
PubMed1994

The crystal structure of affinity-matured human growth hormone at 2 A resolution.

A variant of human growth hormone (hGH), in which 15 mutations were introduced with phage display mutagenesis to improve receptor binding affinity by 400-fold, yielded two related crystal forms diffracting to high resolution. The structure of this variant was determined in both crystal forms, one at 2.0 A resolution and one at 2.4 A resolution, using molecular replacement with wild-type hGH taken from the receptor complex structure as a search model. Crystallographic refinement of the 2 A structure gave an R-value R-value of 18.5% for data in the resolution range 8 to 2 A. The final model consists of residues 1 to 128 and 155 to 191, with three side-chains modeled in alternative conformations, together with 77 water molecules. Comparison of the structure with wild-type hGH shows that most of the secondary structural elements are unchanged. The exception is the first turn of the third helix in the four-helix bundle core, which is unraveled in the present variant. Analysis of the two related packing environments suggests that this change is caused by crystal packing forces. A large change in the orientation of a short segment of helix found in the connection between the first two core helices is interpreted as evidence for rigid-body variability of this helical segment. Analysis of the mutations in light of the structure of the wild-type hGH/receptor complex shows that six of the mutations are buried in the hormone, whereas the remaining nine involve residues that interact with the receptor in the complex.

Amino Acid Sequence↗
PubMed1996

Effects of secondary forces on the ligand binding properties and variable domain conformations of a monoclonal anti-fluorescyl antibody.

Biochemical interactions occurring external to the antibody active site or pocket (i.e. secondary forces) that directly effect ligand binding efficiency, and the microenvironment-sensitive spectral properties of bound homologous ligand, residing within the active site of high affinity monoclonal antifluorescyl antibody (mAb) 4-4-20, have been previously reported. This study describes the synthesis and characterization of a series of specially designed and chemically distinct mono-fluoresceinated peptides of equal size (13-mer) as well as the changes in the spectral properties and free energy in the binding of each fluorescein derivatized peptide, upon interaction with mAb 4-4-20. Significant differences in binding efficiency and fluorescence quenching of the ligand, as well as the intrinsic tryptophan fluorescence, were observed for each monofluoresceinated peptide relative to one another and fluorescein ligand. In addition to the effects on the fluorescence quenching of fluorescein and intrinsic tryptophan residues, and the free energy of binding, the conformation of the variable domains of mAb 4-4-20 upon interaction with the fluoresceinated peptides was probed with polyclonal antimetatype (conformational dependent anti-liganded state) antibodies. Studies comparing the results of a solid-phase inhibition assay, with the binding of antimetatype antibodies in solution, suggested that variant metatypic states of mAb 4-4-20 resulted from binding of the various fluorescein derivatized peptides. Depiction of the mAb 4-4-20 active site as a series of thermally averaged substates is proposed as a model and framework to interpret further the results. It was concluded that secondary forces can dictate conformer selection from the various substates. thereby modulating the primary antibody ligand interaction.

Antibodies, Monoclonal↗
PubMed2002

Folding and aggregation of export-defective mutants of the maltose-binding protein.

We previously characterized a defective-folding variant of the periplasmic maltose-binding protein, MalE31. To examine the alternative folding pathways open to the MalE31 precursor, we have analyzed the cellular fates of this aggregation-prone protein carrying altered signal sequences. Our results are most easily interpreted by a kinetic competition between exportation, folding, and degradation.

Biological Transport↗
PubMed2003

Importance of the D and E helices of the molecular chaperone DnaK for ATP binding and substrate release.

The C-terminal domain of the molecular chaperone DnaK is a compact lid-like structure made up of five alpha-helices (alphaA-alphaE) (residues 508-608) that is followed by a 30-residue disordered, flexible region (609-638). The lid encapsulates the peptide molecule bound in the substrate-binding domain, whereas the function of the 30-residue disordered region is not known. By sequentially deleting the flexible subdomain and the individual lid helices, we deduced the importance of each structural unit to creating long-lived DnaK-peptide complexes. Here we report that (i) the alphaD helix is essential for long-lived DnaK-peptide complexes. For example, ATP triggers the dissociation of a acrylodan-labeled p5 peptide (ap5, a-CLLLSAPRR) from wtDnaK and DnaK595(A-D) with k(off) equal to 7.6 and 8.9 s(-1), respectively, whereas when the D-helix is deleted, creating DnaK578(A-C), k(off) jumps to 207 s(-1). (ii) The presence of the alphaB helix impacts the rate of the ATP-induced high-to-low affinity conformational change. For example, ATP induces this conformational change in a lidless variant, DnaK517(1/2A), with a rate constant of 442 s(-1), whereas, after adding back the B-helix (residues 518-554), ATP induces this conformational change in DnaK554(A-B) with a rate constant of 2.5 s(-1). Our interpretation is that this large decrease occurs because the B-helix of the DnaK554(A-B) is bound in the substrate-binding site. (iii) The deletion analysis also revealed that residues 596-638, which comprise the alphaE helix and the flexible subdomain, affect ATP binding. Our results are consistent with this part of the lid producing conformational heterogeneity, perhaps by binding to the ATPase domain.

Adenosine Triphosphatases↗
PubMedDate not supplied

The evolution of foot morphology in children between 6 and 17 years of age: a cross-sectional study based on footprints in a Mediterranean population.

Footprint evaluation is a widely used method for the determination of foot morphology, but its efficacy and validity are considered controversial. Dynamic footprints were obtained from both feet of 5,866 school-aged children (6-17 years old) to detect any foot changes during growth. The interpretation of the imprint was performed using a classification scheme consisting of 6 types of footprints. In this scheme, footprint types I and II represent the typical and intermediate high-arched foot, respectively. Types III and IV represent normal foot variants, while type V corresponds to the low-arched foot and type VI to the severe flat foot, the latter often encountered in pathological conditions. There was statistically significant difference (P<.05) in footprint-type frequencies between boys and girls of ages 7, 9, 11, 14, and 15, which probably indicates the difference in growth potential of the foot between sexes. The proportion of high- and low-arched foot types decreased with increasing age in both boys and girls. Even though critical changes of the foot are believed to occur during pre-school development, this study shows that considerable changes also take place during school age and until late adolescence.

Adolescent↗
PubMedDate not supplied

Social context and health consequences of the antipsychotics introduction.

BACKGROUND: From the vantage point of fifty years after the introduction of antipsychotics to clinical practice, this article examines the social context and health consequences of their introduction. METHODS: Historical review of literature sources with commentary. CONCLUSIONS: The availability of antipsychotics over nearly half a century has powerfully influenced concepts of mental illness, dominant models of care versus control, health outcomes and side effect burdens. The large demand and economic success of antipsychotic medications is an important driver for research and development as well as sophistication in marketing. Regulatory agencies, funders and clinicians are faced with a moving target as indications for use of antipsychotics move well beyond the traditional core of schizophrenia and acute mania into depression, anxiety, behavioral disturbance with dementia and some forms of personality disturbance. The history of antipsychotics and mental illness is arguably being written as forcefully now, in an environment of rapid scientific change, as was the case in the 1960s era of rapid social change when chlorpromazine prompted a shift of emphasis from asylum to community. Psychosis is a challenge to how we interpret and approach our inner experiences and societal structures. Accordingly, it is not surprising that the history of antipsychotic drugs resonates with a lively interplay of social, health and economic issues and an ongoing quest to comprehend mental phenomena and their variants.

Antipsychotic Agents↗
PubMed2005

The variable number of tandem repeats element in DAT1 regulates in vitro dopamine transporter density.

BACKGROUND: A 40-bp variable number of tandem repeats (VNTR) polymorphism exists in the 15th exon of DAT1, the gene encoding the human dopamine transporter (DAT). Though the VNTR resides in a region encoding the 3' untranslated region (UTR) and does not alter the protein's amino acid sequence, the prevalent 10-repeat variant has shown both linkage and association to Attention Deficit Hyperactivity Disorder (ADHD). In this study, we examined the effects of the DAT1 VNTR on measures of in vitro DAT expression and pharmacology. A series of four DAT1 constructs, each containing the DAT1 coding region, but varying with respect to the downstream presence or content of the 3'UTR, were engineered and stably transfected into an HEK-293 variant using Flp-In integration, an enzyme-mediated, site-specific recombination technology. RESULTS: [3H] Win 35,428 saturation binding assays and DAT immunoblots revealed statistically significant differences in DAT expression attributable to DAT1 genotype. Cells harboring the 10-repeat DAT1 variant were characterized by a Bmax approximately 50% greater than cells with the 9-repeat VNTR; those containing only the DAT1 coding region or the coding region flanked by a truncated 3' UTR resulted in greater DAT density than either of the naturalistic 9- and 10-repeat variants. Competition binding assays showed no statistically significant DAT1 genotype effects on the DAT affinity for methylphenidate, a finding consistent with the positional location of the VNTR. CONCLUSION: This study identified the DAT1 VNTR as a functional polymorphism and provides an interpretive framework for its association with behavioral phenotypes.

Attention Deficit Disorder with Hyperactivity↗
PubMed2005

The role of common variation in drug transporter genes in refractory epilepsy.

Resistance to antiepileptic drugs (AEDs) is one of the most serious clinical problems in epilepsy, and along with AED teratogenicity, perhaps the major concern of epilepsy pharmacogenetics. Studying the genetics of drug resistance in epilepsy is important, as it may identify or confirm key mechanisms underlying this phenomenon that have real clinical importance; it might also offer insights into its prediction and management. Drug resistance in epilepsy is likely to be multifactorial: overactivity of multi-drug transporters provides one likely underlying mechanism through lowering of AED concentration in the epileptogenic focus. Genetic association studies may provide a tool to assess this 'transporter' hypothesis by determining whether differences between individuals contribute to resistance phenotypes. Most of these studies have investigated one variant in the ABCB1 gene, and have provided, thus far, inconclusive evidence. This review also considers current knowledge of the role of genetic polymorphisms in multi-drug transporters in pharmacoresistant epilepsy, to highlight possible confounding factors affecting the implementation and interpretation of association studies in this field.

Anticonvulsants↗