DNA polymerases from hyperthermophiles.
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Biomedical subjects
Publications and source records attributed to J Cline.
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OBJECTIVES: To describe our experience using ketamine sedation to facilitate pediatric critical care procedures, and to document the safety profile of ketamine in this setting. DESIGN: Retrospective consecutive case series. SETTING: Pediatric intensive care unit of a tertiary children's hospital. PATIENTS: Children receiving ketamine for procedural sedation over a 5-year period. INTERVENTIONS: We reviewed patient records to determine indication, dosing, adverse events, inadequate sedation, and recovery time for each sedation. OUTCOME MEASURES: Descriptive features of sedation including adverse events. RESULTS: During the study period, children in our pediatric intensive care unit received ketamine at total of 442 times to facilitate a wide variety of critical care procedures, most commonly central line placement, esophagogastroduodenoscopy, and wound debridement. Most study children had substantial underlying illness (ASA > or = 3 in 88%; ASA > or = 4 in 39%). Inadequate sedation was noted in only nine (2%) procedures. Adverse effects included transient laryngospasm (n = 9), transient partial airway obstruction (n = 5), apnea with bradycardia (n = 1), emesis during the procedure (n = 2), emesis during recovery (n = 9), mild recovery agitation (n = 10), moderate-to-severe recovery agitation (n = 1), and excessive salivation (n = 4). There were no adverse outcomes attributable to ketamine. CONCLUSION: Pediatric intensivists skilled in ketamine administration can safely and effectively administer this drug to facilitate critical care procedures. Despite the ill nature of our patient sample, adverse effects were uncommon.
Helicobacter hepaticus infection causes hepatitis in A/JCr mice but mild or no disease in C57BL/6 mice. Colonization of H. hepaticus in the cecum of experimentally infected A/JCr and C57BL/6 mice was quantified by use of real-time polymerase chain reaction (PCR) analysis with primers for the H. hepaticus cdtB gene and mouse 18srRNA. Eight-week-old mice were experimentally (n = 48) or sham (n = 24) infected with H. hepaticus, then were necropsied 6 months after infection. Liver specimens from experimentally infected mice had negative results of PCR analysis for H. hepaticus; thus, real-time quantification was not attempted. Quantitative PCR analysis of H. hepaticus in cecal specimens indicated that C57BL/6 mice were colonized to a greater extent than were A/JCr mice (P < 0.006). Appreciable typhlitis was not observed, but was consistent with that of previous reports; A/JCr mice developed more severe parenchymal necrosis, portal inflammation, and phlebitis in the liver (P < 0.0001), with mild disease observed in infected C57BL/6 mice. Thus, hepatitis in A/JCr mice caused by H. hepaticus infection is associated with significantly lower colonization levels of H. hepaticus in the cecum, compared with those of hepatitis-resistant C57BL/6 mice. Host responses of A/JCr mice that limit cecal colonization with H. hepaticus may have important roles in the pathogenesis of hepatic lesions.
Alcohol is the most commonly abused substance among adolescents in the United States. Adolescent females are recognized as one group at risk for giving birth to babies with fetal alcohol syndrome (FAS). Sixth through eighth grade Native Americans were surveyed about their attitudes toward and knowledge of FAS risk factors and prevention strategies. Data revealed that 52% of students drank alcohol prior to the survey. Though sexually active, students lacked knowledge about the relationship between alcohol and FAS. The study revealed 1) limited prevention programs in middle schools and 2) the most influential factor in determining attitudes and decisions about alcohol use was the immediate family. Students felt FAS prevention is an important topic in school health education, noting the important role peers play in teaching and role modeling. Various strategies incorporating music and communication technology such as videotape and computer-assisted interactive tools into prevention materials are discussed.
The replication fidelities of Pfu, Taq, Vent, Deep Vent and UlTma DNA polymerases were compared using a PCR-based forward mutation assay. Average error rates (mutation frequency/bp/duplication) increased as follows: Pfu (1.3 x 10(-6)) < Deep Vent (2.7 x 10(-6)) < Vent (2.8 x 10(-6)) < Taq (8.0 x 10(-6)) < < exo- Pfu and UlTma (approximately 5 x 10(-5)). Buffer optimization experiments indicated that Pfu fidelity was highest in the presence of 2-3 mM MgSO4 and 100-300 microM each dNTP and at pH 8.5-9.1. Under these conditions, the error rate of exo- Pfu was approximately 40-fold higher (5 x 10(-5)) than the error rate of Pfu. As the reaction pH was raised from pH 8 to 9, the error rate of Pfu decreased approximately 2-fold, while the error rate of exo- Pfu increased approximately 9-fold. An increase in error rate with pH has also been noted for the exonuclease-deficient DNA polymerases Taq and exo- Klenow, suggesting that the parameters which influence replication error rates may be similar in pol l- and alpha-like polymerases. Finally, the fidelity of 'long PCR' DNA polymerase mixtures was examined. The error rates of a Taq/Pfu DNA polymerase mixture and a Klentaq/Pfu DNA polymerase mixture were found to be less than the error rate of Taq DNA polymerase, but approximately 3-4-fold higher than the error rate of Pfu DNA polymerase.
We have developed a facile procedure for rapid PCR-based site-directed mutagenesis of double-stranded DNA. Increasing the initial template concentration and decreasing the PCR cycles to 5-10 allows us to reduce the rate of undesired second-site mutations and dramatically increase the time savings. Following PCR, DpnI treatment is used to select against parental DNA molecules. The DpnI (target sequence 5'-Gm6ATC) is specific for methylated and hemimethylated DNA and is used to digest parental DNA and select for mutation-containing amplified DNA. DNA isolated from almost all common Escherichia coli strains is Dam methylated and therefore susceptible to DpnI digestion. Pfu DNA polymerase is used, prior to intramolecular ligation of the linear template, to remove any bases extended onto the 3' ends of the PCR product by Taq DNA polymerase. The recircularized vector DNA incorporating the desired mutations is transformed into E. coli. This method can be used independently of any host strain and vector.
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This study examined hospital utilization and, specifically, unnecessary hospital days for patients with acquired immunodeficiency syndrome (AIDS) in a Midwest regional referral center as of June 1987. In 1990 a follow-up study was conducted to measure changes in length of stay (LOS) and unnecessary days. Results show a mean LOS consistent with other studies and a pattern of unnecessary days comprising 14% to 18% respectively of the mean LOS. Admissions in which the patient died and those considered outliers (LOS greater than 36 days) had a trend toward a higher percentage of unnecessary days. Hospital utilization and unnecessary days for patients with AIDS should be an ongoing quality indicator for hospitals experiencing a high volume of persons with AIDS admissions.
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Of the many techniques which have been used to introduce new genes into cells, four are of particular interest for gene therapy. Transfection has been most extensively studied and has been used to put new genes into mice and men. Homologous recombination offers the promise of curing certain mutations in situ, but is still largely unexplored. Injection of new genes into the nuclei of single cell embryos has had startling successes in animals, but there are many scientific and ethical issues to be resolved before such an approach can be considered for gene therapy. Retroviral vectors currently offer the most exciting prospect for introducing useful gene sequences into defective cells; however, safety issues and problems of low levels of gene expression are still to be resolved. It appears likely that the bone marrow will be the first target of gene therapy for genetic diseases. The marrow is accessible and contains proliferating stem cells which can transmit the new genes to progeny cells. The possibility of treating enzyme deficiency diseases and hemoglobinopathies by gene transfer is attractive. Experiments in two patients with thalassemia major indicate that it is feasible to introduce new genes into bone marrow cells of man and return the modified cells to hematopoietic sites.
Synthetic oligonucleotide probes have been used to identify two overlapping cDNA clones that represent the entire coding region of the mRNA for the major intrinsic protein (MIP) of bovine lens cell membrane. Hybridization studies indicate that bovine MIP is encoded by a single-copy gene. The cDNA hybridizes to the rat genome, but MIP mRNA is not detected in rat liver. Analysis of the deduced amino acid sequence provides support for the potential role of MIP as a junctional protein. The structure predicted for MIP suggests that it traverses the lipid bilayer six times with both carboxy and amino termini on the cytoplasmic side, and that it has at least one amphiphilic transmembrane segment, as expected if the protein were to participate in the formation of an aqueous channel.
To determine the clinical significance of splenic uptake in bone scintigraphy and functional asplenia on the radionuclide liver-spleen image, bone and spleen scintigrams of 38 patients with sickle cell disease were reviewed. Eighteen underwent bone and liver-spleen studies, 15 had only bone images, and five had only liver-spleen studies. Sixteen of 33 who had bone scintigraphy showed splenic uptake, but the frequency of homozygous sickle cell (SS) disease was not greater than heterozygous sickle cell disease (S-hetero) in this group. SS patients with splenic uptake of Tc-99m diphosphonate had significantly fewer painful crises of the abdomen and extremities, and fewer inpatient and outpatient hospital visits than SS patients whose bone imaging did not visualize the spleen. Functional asplenia on liver-spleen images (16 cases) was seen only in SS disease. One SS patient, age 8, still had a spleen capable of phagocytizing colloid.
A new rhombic EPR signal was recently discovered in the partially reduced type 2 copper-depleted Rhus vernicifera laccase (Reinhammar, B. (1983) J. Inorg. Biochem., in press). The signal originates from one of the type 3 Cu(II) ions that becomes EPR-detectable as a result of the selective reduction of the other copper ion in the exchange-coupled Cu(II)-Cu(II) pair. The 14N and 1H and 63,65Cu electron nuclear double resonance (ENDOR) of this uncoupled Cu(II) now have been collected and represent the first ENDOR measurements of a type 3 copper site. The data indicate that the copper is coordinated by at least three nitrogenous ligands, at least one of which is an imidazole. H/D exchange suggests a nearby H2O or OH-, perhaps as a fourth ligand. A similar EPR signal is seen for CuB of reduced cytochrome c oxidase under turnover conditions. The 14N ENDOR, and, therefore, the structure, of this site corresponds extremely closely to that of the laccase type 3 (Cu(II).
A previously reported technique for the assessment of skin blood flow in the lower extremities of patients with ischemic lesions was evaluated using intracutaneous xenon clearance. The radioisotope was injected above and below both the ankle and the knee and flow was measured using a gamma camera with a low-energy collimator, 88-keV photopeak, and a 20% window. Healing was more frequent when skin blood flow was equal to or greater than 2.4 ml/min/100 g (38/39 patients) than when flow was less than 2.4 ml/min/100 g (4/7 patients). The authors conclude that this technique can be used to help determine the appropriate site for amputation in lower limb ischemic lesions.
The absolute and relative bioavailability of levothyroxine was determined in young, healthy male subjects after administration of i.v. solution, p.o. solution, or one of two brand-name, commercially available tablets. The mean dose size was about 0.18 mg. Serum concentration-time data were obtained over a period of 50 h. The absolute bioavailabilities of the two tablet preparations were 66% and 72%, respectively.
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