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Biomedical subjects

B Burk

Publications and source records attributed to B Burk.

11 recordsLinked to original sources
PubMed1995

Differential splicing of the mouse B-myb gene.

The myb gene family consists of three members, the c-myb proto-oncogene and two myb-related genes (A-myb and B-myb), all of which encode nuclear DNA-binding proteins. Unlike c-myb, which plays a critical role in hematopoietic cells, B-myb is expressed in a large spectrum of hematopoietic as well as non-hematopoietic cells and has been implicated in the control of cell proliferation. The isolation of B-myb cDNA clones from several species has shown that B-myb shares limited homology to the so-called exon 9A of the c-myb gene. This exon is involved in differential splicing as only a subfraction of c-myb mRNA contains exon 9A sequences. The presence in the B-myb cDNA of a sequence related to the exon 9A of c-myb has prompted us to investigate whether B-myb mRNA is also spliced differentially. We here show that B-myb mRNAs containing or lacking exon 9A related sequences are present in many cell types. In contrast to c-myb, where RNA containing the exon 9A constitutes only a minor mRNA fraction, B-myb RNA containing the exon 9A related sequences is the major mRNA form. The proteins encoded by the two B-myb mRNA species are unable to activate promoters to which they bind. Curiously, both B-myb proteins differ in their ability to activate the HSP70 promoter by a myb binding-site independent mechanism; B-myb protein containing exon 9A related aminoacid sequences activates the HSP70 promoter much more potently than the B-myb protein which lacks these sequences. Our results suggest that differential splicing may be a general feature of the members of the myb family and provide first evidence for functional differences of the splice variants.

Amino Acid Sequence↗
PubMed1994

[Long-functioning beta-D-glucose and L-lactate biosensors for continuous flow-through measurements for "fouling"-resistant and selectivity-optimized serum- and hemoanalysis].

Bioelectrochemical membrane-electrodes for O2-sensitive enzymatic flow-through analysis of beta-D-glucose and L-lactate are described. The enzyme-membranes of the biosensors consist of glucose-oxidase or lactate-oxidase molecules cross-linked with glutardialdehyde between two dialysis membranes. The accuracy of the biosensors is demonstrated by electroanalysis of diluted control serum and compared with redox-mediator-free H2O2 detection and photometric methods. Continuous haemoanalysis of uncoagulated blood was carried out, using an intermediate carrier stream with additive systems. Tangential streaming to the miniaturized dialysis chamber with a circular channel minimizes blockage of the pores of the dialysis membrane by erythrocytes, leukocytes or protein. An oxygenator pump for the exchange of gases between the buffered solution of the intermediate carrier and the surrounding atmosphere guarantees a constant oxygen partial pressure within the carrier stream. The pulsations produced by the oxygenator pump are dampened by a miniature pressure balance chamber with an unsignificant dead space volume for protecting the enzyme membrane of the sensor. Glutardialdehyde inhibits growth of microorganisms and any resulting oxygen consumption, so that even in protein-containing measuring solutions enzyme electrodes can be used without interference from microbial contamination. The bioelectrochemical measuring system can therefore also be employed for the electroanalysis of fermentation solutions. For continuous flow-through measurements, it is necessary to change the glucose-oxidase membranes after 100-150 days, and the lactate-oxidase membranes after 3-6 weeks.

Biosensing Techniques↗
PubMed1994

[Urea sensor for the continuous ammonium-selective enzymatic process control of the artificial kidney].

Presented is a flow-through method for continuous ammonium-selective enzymatic monitoring of the artificial kidney by means of a bioelectrochemical urea electrode. The urea is converted in an enzyme membrane by covalently bound urease and the ammonium ions are detected by a Nonactin-PVC-membrane. In addition to detailed data from the oxygen-independent solid-state contact sensor, curves are obtained on-line from the patient during the haemodialysis session. The advantages of the method are described in detail. Furthermore, the urea sensor can be used for measurements in heparinized blood.

Anti-Bacterial Agents↗
PubMed1992

Influence of assay methods on serum concentrations of digoxin during FAB fragment treatment.

The treatment of digoxin intoxication has been revolutionized by digoxin specific antibody fragments (Fab). Serum digoxin concentrations may be inaccurate after this treatment. We report a case of digoxin intoxication where the results of serum concentration determinations were strikingly disparate depending on the assay used. To investigate this discrepancy we compared serum samples spiked with digoxin from 0-50 ng/mL in the presence of increasing concentrations of digoxin specific Fab-fragments. Samples were measured using the Abbott TDx assay with and without ultrafiltration of the sample and the Dade-Stratus radial partition assay. The TDx assay was statistically reduced by the Fab-fragments although the magnitude of the effect was small. The radial partition assay was dramatically affected by the addition of Fab-fragments. The predicted non-Fab bound concentration correlated highly with the measured concentration. When samples were ultrafiltered prior to TDx assay, the measured concentration was dramatically depressed but the regression of predicted non-Fab bound concentration versus observed had a significantly lower slope than for the radial partition assay. We hypothesize that this difference is due to serum protein binding in addition to Fab-fragment binding. We conclude that the radial partition assay gives the best approximation of digoxin concentration remaining unbound to Fab-fragments. Ultrafiltration followed by TDx assay gives an acceptable approximation.

Antigen-Antibody Reactions↗
PubMed1991

[Modified use of training of socially insecure children from socio-culturally deprived social classes. A single case related study with children of a day care group].

In this paper a combination of individual- and group-training with unassertive children is described with strongly deprived children from a daily pedagogical institute. Instead of systematic parent's consulting other supportive elements like consulting with educators and teachers, intensive in-vivo-practices, weekly letters with homework etc. were used. Single case design and evaluating on the basis of a A-B-A-C design and a follow-up after eight weeks with three social disadvantaged children at the age of nine to eleven years were used to evaluate the effectiveness of the program. Goal-attainment-scaling was used for each of the five to seven behavioral outcome measures in the individual- and group-training by video. The administration of this program proved to be effective and efficient. The improvements were above the expectations of the training's aims and were stable over a follow-up period.

Behavior Therapy↗
PubMed1989

Resistance of influenza A virus to amantadine and rimantadine: results of one decade of surveillance.

All clinical isolates of influenza A viruses from patients in Huntington, West Virginia, during the decade 1978-1988 were tested, and 65 of 65 H1N1 and 176 of 181 H3N2 viruses were susceptible to the antiviral action of amantadine and rimantadine. The five resistant viruses were obtained from three members of a family undergoing therapy or prophylaxis with rimantadine. Resistant influenza emerged during treatment with rimantadine and spread to two family contacts, causing typical influenza with fever, myalgia, and cough of 5 days' or less duration. Genetic characterization of the resistant viruses when compared to the susceptible virus isolated on day 1 from the index case revealed a single amino acid change in the transmembrane portion of the M2 protein. In vitro studies showed that rimantadine was significantly more active than amantadine against both H1N1 and H3N2 viruses. Although this resistant influenza was transmitted and caused illness in one family, the absence of naturally occurring resistant viruses suggests that the emergence of new strains of influenza A each few years may prevent the widespread emergence of resistant influenza A virus.

Adamantane↗
PubMed1989

Evaluation of cold-recombinant influenza A/Korea (CR-59) virus vaccine in infants.

Twenty-four infants 5 to 13 months of age were intranasally vaccinated with a live cold-recombinant influenza A/Korea (CR-59, H3N2) virus vaccine. Nineteen infants served as controls. The inocula ranged from 10(3.2) to 10(6.2) 50% tissue culture infective doses (TCID50) per infant. Zero of six, one of four, seven of ten, and four of four infants receiving 10(3.2), 10(4.2), 10(5.2), and 10(6.2) TCID50, respectively, were infected by the intranasal vaccine. The amount of virus required to infect 50% of infants was calculated to be 10(4.6) TCID50. The occurrence of fever, respiratory illness, and otitis media was common among both controls and vaccinees in the postinoculation period. Maternal antibody was present in low titers in some infants and did not inhibit replication of the vaccine virus.

Administration, Intranasal↗
PubMed1985

Voluntary control of reversible figures.

This study was designed to demonstrate that voluntary control of the perception of reversible figures is possible. Within the context of a fully counterbalanced design, some subjects were given instructions as to which side of a reversible screen or staircase to keep closer while others served as no instruction controls. As predicted, voluntary control was clearly demonstrated over both figures. Voluntary control instructions did not influence the frequency of reversals directly, but frequency of reversals and voluntary control were inversely related. Moreover, subjects' voluntary control over one figure was highly correlated with their control over the other, suggesting the presence of stable individual differences in ability to control perception voluntarily.

Cognition↗