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PubMed2002

Expression of protein tyrosine kinase pp60v-src variants in Dictyostelium discoideum.

We achieved production of v-Src of the low-oncogenic PRC and its variant proviral structure H19 in Dictyostelium discoideum, an emerging host system suitable for synthesis of heterologous proteins. To accomplish their expression, the first six codons of the N-terminus of v-src had to be changed according to the D. discoideum codon preference. Alternatively, N-terminal fusions of 6xHis-tag or GFP were sufficient to overcome the incompatibility in codon usage. D. discoideum-expressed v-Src kinases of the expected molecular weight were recognized by Src-specific antibodies; GFP-PRC was distributed uniformly in the cytosol. In contrast to other lower eukaryotes, where the accumulation of v-Src leads to growth inhibition, D. discoideum cells silenced the kinase activity of PRC-derived v-Src and showed no developmental or growth defects.

Animals↗
PubMed1990

A simple approach to the determination of the gamma chain composition of HB F in adult human blood samples.

A procedure for the determination of the gamma chain heterogeneity of adult human blood samples with low Hb F has been developed. It consists of the isoelectrofocusing of lysates at a rather high hemoglobin concentration, the isolation of the focused Hb F by elution from the gel, and the analysis of the isolated hemoglobin by reversed phase high performance liquid chromatography for the separation and quantitation of globin chains. Depending on the isoelectrofocusing apparatus, many samples with as little as 1% Hb F may be focused in a single run and the gamma chain composition of the recovered hemoglobin (enriched from 15% to 95% in Hb F) easily analyzed by high performance liquid chromatography. The same procedure might be used for the isolation of low level hemoglobin variants for structural studies.

Adult↗
PubMed1994

The use of Staphylococcus V8 protease in the structural determination of human hemoglobin variants: HB Valparaiso [alpha 88(F9)Ala-->Gly] example.

In human hemoglobin, enzymic cleavage with the protease from Staphylococcus aureus strain V8 (protease V8) is a convenient method for the study of variants that involve large peptides such as alpha T-9 and alpha T-12b. We report here on Hb Valparaiso [alpha 88(F9)Ala-->Gly], a new neutral variant with a slight increase in oxygen affinity, that was identified by use of this strategy.

Female↗
PubMed1998

HB Les Andelys [alpha83(F4)LEU-->PRO]: a new moderately unstable variant.

Hb Les Andelys [alpha83(F4)Leu-->Pro] is a mildly unstable variant that was found during glycated hemoglobin measurement in a French family. In this hemoglobin molecule the affected site, in the alpha chain, and the amino acid substitution are identical to those of Hb Santa Ana, an unstable beta chain variant. The structural abnormality was demonstrated by protein chemistry methods, involving, in addition to the classical techniques, a selective precipitation of the abnormal hemoglobin by isopropanol and a mass spectrometry analysis of the alphaT-9 peptide following carboxypeptidase digestion. DNA sequencing demonstrated that the mutation was CTG-->CCG at codon 83 of the alpha2 gene.

Amino Acid Sequence↗
PubMed2001

[Mobile genetic element MDG4 (gypsy) in Drosophila melanogaster. Features of structure and regulation of transposition].

Distribution of two structural functional variants of the MDG4 (gypsy) mobile genetic element was examined in 44 strains of Drosophila melanogaster. The results obtained suggest that less transpositionally active MDG4 variant is more ancient component of the Drosophila genome. Using Southern blotting, five strains characterized by increased copy number of MDG4 with significant prevalence of the active variant over the less active one were selected for further analysis. Genetic analysis of these strains led to the suggestion that some of them carry factors that mobilize MDG4 independently from the cellular flamenco gene known to be responsible for transposition of this element. Other strains probably contained a suppressor of the flam- mutant allele causing active transpositions of the MDG4. Thus, the material for studying poorly examined relationships between the retrovirus and the host cell genome was obtained.

Animals↗
PubMed2002

Multiple splice variants of lactate dehydrogenase C selectively expressed in human cancer.

We applied a combined data mining and experimental validation Approach for the discovery of germ cell-specific genes aberrantly expressed in cancer. Six of 21 genes with confirmed germ cell specificity were detected in tumors, indicating that ectopic activation of testis-specific genes in cancer is a frequent phenomenon. Most surprisingly one of the genes represented lactate dehydrogenase C (LDHC), the germ cell-specific member of the lactate dehydrogenase family. LDHC escapes from transcriptional repression, resulting in significant expression levels in virtually all tumor types tested. Moreover, we discovered aberrant splicing of LDHC restricted to cancer cells, resulting in four novel tumor-specific variants displaying structural alterations of the catalytic domain. Expression of LDHC in tumors is neither mediated by gene promotor demethylation, as previously described for other germ cell-specific genes activated in cancer, nor induced by hypoxia as demonstrated for enzymes of the glycolytic pathway. LDHC represents the first lactate dehydrogenase isoform with restriction to tumor cells. In contrast to other LDH isoenzymes, LDHC has a preference for lactate as a substrate. Thus LDHC activation in cancer may provide a metabolic rescue pathway in tumor cells by exploiting lactate for ATP delivery.

Alternative Splicing↗
PubMedDate not supplied

Hydrophobic interaction chromatography of recombinant human growth hormone, Genotropin.

A recombinant human growth hormone preparation (rhGH) has been used to study the effects of temperature, pH and detergent (Brij 35) concentration on the selectivity, recovery and retention time, during hydrophobic interaction chromatography (HI-HPLC) on a TSK-phenyl-5PW column. The rhGH preparation used in the study contained two rhGH variants, e.g. LMWGH and Clip I. These variants are structurally very similar to rhGH and exhibited very similar chromatographic behaviour to rhGH, important in evaluation of selectivity. Structural studies revealed that LMWGH had lost the first N-terminal amino acid residue, phenylalanine. Clip I exhibited an increased molecular mass of 32.7 Da for the C-terminal tryptic fragment T18-T19. Temperature and pH were found to influence retention time, sharpness of peaks and selectivity. Furthermore, recoveries were improved from 50% to 99% for rhGH upon the introduction of 0.075% Brij 35, a non-ionic detergent, in the presence of 5% acetonitrile. The optimized HI-HPLC system was found to exhibit good recoveries and excellent selectivity. The system is suitable both as an in-process chromatographic purification step for rhGH, as well as an analytical test method for purity and potency.

Amino Acid Sequence↗
PubMed1992

Screening cord blood for hemoglobinopathies and thalassemia by HPLC.

We evaluated the use of an HPLC method for screening hemoglobins in cord blood. We studied the genotype frequencies of the structural hemoglobin variants HbS and HbC and the synthesis variants alpha- and beta(+)-thalassemia in babies born on Curaçao. During three months, 67.2% of all (748) newborns were screened: 122 (24.3%) had an abnormal hemoglobin pattern, of which 53 (43.4%) had a hemoglobinopathy (HbS or HbC), 64 (52.2%) had alpha-thalassemia (HbBarts greater than 0.5%, corresponding to heterozygous or homozygous alpha-thalassemia-2), and 5 (4.1%) had a hemoglobinopathy plus alpha-thalassemia. None of the newborns with heterozygous HbS and HbC had concomitant beta(+)-thalassemia. The population genotype frequency of heterozygous alpha-thalassemia-2 was calculated to be 30.7%. The data are in excellent agreement with those previously established for the adult population and those available from the black population in the United States and Jamaica. Based on the HPLC results, we estimate that 67.1% of newborns with heterozygous alpha-thalassemia-2 remain undetected. A coincidental finding was a relation between demonstrable alpha-thalassemia and short gestation. Because of its superior separating power and high sensitivity for quantifying relatively low percentages of hemoglobins in the presence of HbF0, the HPLC method was preeminently suitable for screening cord-blood samples.

Chromatography, High Pressure Liquid↗
PubMed1975

Hemoglobin J-Chicago (beta76(E20) Ala yields Asp): a new hemoglobin variant resulting from substitution of an external residue.

An electrophoretically fast-moving hemoglobin variant was found in a 2-yr-old boy who was referred for evaluation with findings of iron deficiency anemia. The anemia was corrected, and no hematologic abnormality remained after treatment with iron. Oxygen affinity of the blood was normal, and no evidence was found of instability of the variant hemoglobin. Structural studies demonstrated a substitution of aspartic acid for alanine at beta76 (E20). This change did not appear to cause any functional disruption of the hemoglobin in this patient, as would be predicted by the position of the affected animo acid residue on the surface of the molecule.

1-Propanol↗
PubMedDate not supplied

Amantadine resistance among hemagglutinin subtype 5 strains of avian influenza virus.

Several avian influenza virus strains of hemagglutinin subtype 5 were assayed for sensitivity to the antiviral drug amantadine. Most strains exhibited little sensitivity to the drug as measured by plaque reduction. The A/Chicken/Scotland/59 (CS59), however, was highly sensitive, making it easily distinguishable from the other H5 strains. Drug sensitivity of the viruses was also assayed in chicken embryos. The in ovo patterns of amantadine sensitivity differed from those detected in cell culture. The CS59 isolate could not be distinguished from all the other strains on the basis of its response to amantadine in ovo. Although amantadine protected chickens inoculated with CS59 from morbidity and mortality, drug-resistant viruses were readily isolated from the infected birds. As found with other amantadine-resistant variants, the structure of the matrix gene was altered in the resistant isolates. These results demonstrate that amantadine resistance is widespread among avian influenza viruses of the H5 subtype, that drug sensitivity in cell culture does not necessarily reflect responses to amantadine in ovo and in vivo, and, as previously found, amantadine-resistant derivatives of H5 strains may be isolated from birds protected by the drug.

Amantadine↗
PubMed1989

Abdominal mass lesions in the newborn: diagnosis and treatment.

Most neonatal abdominal masses will be due to benign retroperitoneal lesions such as hydronephrosis and multicystic dysplastic kidney. Although history and physical examination, plain radiographs and ultrasonography will confirm most diagnoses, severe unilateral hydronephrosis, hemorrhagic neuroblastoma, and intraperitoneal cysts may provide diagnostic difficulties. Masses identified by prenatal ultrasound need careful evaluation as they may represent normal structures, nonsignificant variants, or physiologically significant anomalies. Many lesions will require operative intervention, which can be safely performed in small infants by trained personnel at facilities with appropriate support services. Genuine controversy exists in the management of some of these lesions including MDK, renal vein thrombosis, and acalculous cholecystitis.

Abdominal Neoplasms↗
PubMed1988

Functional characterization of thrombin Salakta: an abnormal thrombin derived from a human prothrombin variant.

The genetic variant prothrombin Salakta has been described in a patient presenting with a normal level of prothrombin antigen but reduced prothrombin activity. Initial studies indicated that factor Xa-catalyzed cleavages proceed normally but lead to the production of a thrombin molecule with an altered enzymatic activity. To characterize the functional abnormality of thrombin Salakta more precisely, it was purified by chromatography on heparin-Sepharose and diethylaminoethyl-Sephadex. The purified variant does not differ from normal thrombin by size, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and is 93.1% +/- 7.6% active by titration with p-nitrophenyl-p'-guanidinobenzoate. Its activity, however, is altered to various extents toward the following substrates: H-D-phenylalanyl-L-pipecolyl-L-arginine paranitroanilide (S 2238), fibrinogen, factor V, protein C, and antithrombin III. The Michaelis constant (Km) of thrombin Salakta for S 2238 is higher (12.2 +/- 3.3 mumol/L) than normal (2.8 +/- 0.7 mumol/L), whereas the turnover number (Kcat) is normal (84.4 +/- 6.6 s-1 v 85.9 +/- 14.0 s-1 for normal thrombin). The interaction of thrombin Salakta with benzamidine is also altered as evidenced by an increased inhibition constant (Ki = 3.5 mmol/L v 0.28 mmol/L for normal thrombin). The inability of fibrinogen to act as a competitor in the inactivation of thrombin Salakta by diisopropylfluorophosphate clearly indicates that fibrinogen binding to the fibrinopeptide groove is drastically impaired. In contrast, interactions involving sites remote from the active site such as those with fibrin and thrombomodulin are only slightly impaired. These results indicate that thrombin Salakta exhibits a specific pattern of functional alterations different from those reported for other variants. The structural defect seems to affect essentially the primary substrate binding site and to a lesser extent recognition site(s) remote from the catalytic site such as those for fibrin and thrombomodulin.

Catalysis↗