Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One of the easiest and most sensitive methods of detecting mutations in the beta-globin gene leading to beta-thalassemia is by the use of oligonucleotide probes. The current method involves digestion of 5-10 micrograms of genomic DNA followed by gel electrophoresis, and blotting onto nitrocellulose. The membrane is then hybridized with a 32P-radiolabeled oligonucleotide probe containing the specific point mutation of interest. Finally, the membrane is subjected to X-ray film for 3-10 days. We wish to report a method for detecting these mutations which involves 1 microgram of genome DNA or less. The method involves the use of a gene amplification technique. A series of primers are synthesized which span the beta-globin gene. In each primer set, one primer is complementary to the beta-gene and the other primer is complementary to the non-coding strand. The suspected mutation point is located between these two primers. With the use of this primer set, the beta-globin gene region is amplified by denaturing, annealing, and DNA synthesis. The amplification cycle is repeated 25 to 30 times. The amplification is conducted using the Klenow fragment of DNA polymerase I or Taq polymerase in the presence of all four deoxynucleotide triphosphates. The resulting amplified DNA is applied to a nylon membrane with the aid of a dot-blot apparatus and directly hybridized with normal and mutant deoxynucleotide probes. The entire process requires one to two days. More than 300 beta-thalassemia homozygotes have been identified in our laboratories; over 20 different mutations have been observed.
Hemoglobin 1988
PMID:Newer developments in the identification of beta-thalassemia. 320 97

A new method for labeling oligonucleotides was developed to obtain high specific activity of radioactive probes. In an oligonucleotide molecule, two sequences were designed. One sequence, the 5', contains 19 nucleotides and serves as a template for probe synthesis. The second sequence, 3', contains a consensus sequence which forms a Pst I site after forming a complementary strand with the primer. In the presence of E. coli DNA polymerase I (Klenow fragment), alpha-32P dNTP and other dNTPs, a radioactive labeled oligonucleotide was synthesized by the primer extension method. After Pst I digestion, the probe was different from its template in length by 4 bp and could be separated from each other on urea-polyacrylamide gel electrophoresis (PAGE). A radioactive oligonucleotide probe with extremely high specific activity up to 10(10) dpm/micrograms could be obtained by the use of this method. The oligonucleotide probes have been used for the detection of the Hb E mutation in this report.
Hemoglobin 1988
PMID:Restriction primer extension method of labeling oligonucleotide probes and its application to the detection of Hb E genes. 320 11

Hemoglobin mRNA and (rA)(n).(dT)(10) have been used as primer-templates in a kinetic study of DNA synthesis with Escherichia coli DNA polymerase I (DNA nucleotidyl transferase, EC 2.7.7.7) and Mason-Pfizer monkey virus reverse transcriptase (RNA-directed DNA polymerase). The rate versus enzyme concentration curve is sigmoidal and is consistent with a cooperative phenomenon. The results could be interpreted in terms of the formation of an active complex containing enzyme dimers (or oligomers) on the primer-template. We have also observed sigmoidal kinetics in rate versus deoxynucleotide triphosphate concentration. These results are consistent with an allosteric mechanism in which the triphosphates act as both modifiers and DNA precursors. In the critical range, a 6- to 8-fold increase in both enzyme and triphosphate concentrations can lead to a 1500-fold increase in the rate of synthesis on an RNA template. Thus, small changes in enzyme and precursor concentrations could play a regulatory role in vivo.
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PMID:Evidence for allosterism in in vitro DNA synthesis on RNA templates. 413 34

Acute human immunodeficiency virus (HIV) seroconversion illness is a difficult diagnosis to make because of its nonspecific and protean manifestations. We present such a case in an adolescent. A 15-year-old boy presented with a 5-day history of fever, sore throat, vomiting, and diarrhea. The patient also reported a nonproductive cough, coryza, and fatigue. The patient's only risk factor for HIV infection was a history of unprotected intercourse with 5 girls. Physical examination was significant for fever, exudative tonsillopharyngitis, shotty cervical lymphadenopathy, and palpable purpura on both feet. Laboratory studies demonstrated lymphopenia and mild thrombocytopenia. Hemoglobin, serum creatinine, and urinalysis were normal. The following day, the patient remained febrile. Physical examination revealed oral ulcerations, conjunctivitis, and erythematous papules on the thorax; the purpura was unchanged. Serologies for hepatitis B, syphilis, HIV, and Epstein-Barr virus were negative. Bacterial cultures of blood and stool and viral cultures of throat and conjunctiva showed no pathogens. Coagulation profile and liver enzymes were normal. Within 1 week, all symptoms had resolved. The platelet count normalized. Repeat HIV serology was positive, as was HIV DNA polymerase chain reaction. Subsequent HIV viral load was 350 000, and the CD4 lymphocyte count was 351/mm3. HIV is the seventh leading cause of death among people aged 15 to 24 in the United States, and up to half of all new infections occur in adolescents. Our patient presented with many of the typical signs and symptoms of acute HIV infection: fever, fatigue, rash, pharyngitis, lymphadenopathy, oral ulcers, emesis, and diarrhea. Other symptoms commonly reported include headache, myalgias, arthralgias, aseptic meningitis, peripheral neuropathy, thrush, weight loss, night sweats, and genital ulcers. Common seroconversion laboratory findings include leukopenia, thrombocytopenia, and elevated transaminases. The suspicion of acute HIV illness should prompt virologic and serologic analysis. Initial serology is usually negative. Diagnosis therefore depends on direct detection of the virus, by assay of viral load (HIV RNA), DNA polymerase chain reaction, or p24 antigen. Both false-positive and false-negative results for these tests have been reported, further complicating early diagnosis. Pediatricians should play an active role in identifying HIV-infected patients. Our case, the first report of acute HIV illness in an adolescent, emphasizes that clinicians should consider acute HIV seroconversion in the appropriate setting. Recognition of acute HIV syndrome is especially important for improving prognosis and limiting transmission. It is imperative that we maintain a high index of suspicion as primary care physicians for adolescents who present with a viral syndrome and appropriate risk factors.
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PMID:Acute human immunodeficiency virus syndrome in an adolescent. 1452 19

To determine the prevalence of the sickle cell gene (betaS) in Yemen and amongst people from different regions of the country living in the capital, Sana'a City, cord blood samples from 1,500 consenting mothers were collected from hospitals in Sana'a City between July and December 2001. The names and original homes of the parents were recorded. Cation exchange high performance liquid chromatography (HPLC) analysis was used for screening, while isoelectric focusing (IEF) and DNA polymerase chain reaction (PCR) were used to confirm Hb S [beta6(A3)Glu-->Val]. Thirty-three samples were found to show Hb FAS, giving an overall likely betaS gene frequency of 0.011. The betaS gene frequency varied with the part of the country from which the parents came. Amongst people from Taiz and Haja in the west, the gene frequency was more than 0.04, but less than 0.004 amongst people from Ibb, adjacent to the governorate (administrative division) of Taiz. Of 66 chromosomes from babies carrying the betaS gene, only 1.5% also carried the -158 (C-->T) Ggamma-globin gene XmnI site compared with 16.1% of 168 chromosomes from babies without the betaS gene from the same regions. The results of this study show a higher betaS gene frequency in the western coastal part of Yemen than in the central mountainous and eastern desert areas. The incidence of affected homozygous births may therefore reach 20/10,000 in certain areas, although it is much lower than this overall. Limited health resources can best be invested in developing a program of education, screening and health care, initially prioritizing those communities residing in the western areas of Yemen with the highest betaS gene frequency.
Hemoglobin 2004
PMID:Prevalence of the sickle cell gene in Yemen: a pilot study. 1565 86

Blood samples are widely used for PCR-based DNA analysis in fields such as diagnosis of infectious diseases, cancer diagnostics, and forensic genetics. In this study, the mechanisms behind blood-induced PCR inhibition were evaluated by use of whole blood as well as known PCR-inhibitory molecules in both digital PCR and real-time PCR. Also, electrophoretic mobility shift assay was applied to investigate interactions between inhibitory proteins and DNA, and isothermal titration calorimetry was used to directly measure effects on DNA polymerase activity. Whole blood caused a decrease in the number of positive digital PCR reactions, lowered amplification efficiency, and caused severe quenching of the fluorescence of the passive reference dye 6-carboxy-X-rhodamine as well as the double-stranded DNA binding dye EvaGreen. Immunoglobulin G was found to bind to single-stranded genomic DNA, leading to increased quantification cycle values. Hemoglobin affected the DNA polymerase activity and thus lowered the amplification efficiency. Hemoglobin and hematin were shown to be the molecules in blood responsible for the fluorescence quenching. In conclusion, hemoglobin and immunoglobulin G are the two major PCR inhibitors in blood, where the first affects amplification through a direct effect on the DNA polymerase activity and quenches the fluorescence of free dye molecules, and the latter binds to single-stranded genomic DNA, hindering DNA polymerization in the first few PCR cycles. Graphical abstract PCR inhibition mechanisms of hemoglobin and immunoglobulin G (IgG). Cq quantification cycle, dsDNA double-stranded DNA, ssDNA single-stranded DNA.
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PMID:Inhibition mechanisms of hemoglobin, immunoglobulin G, and whole blood in digital and real-time PCR. 2950 82