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Biomedical subjects

H G Busse

Publications and source records attributed to H G Busse.

15 recordsLinked to original sources
PubMed1998

Sustained oscillations in glycolysis: an experimental and theoretical study of chaotic and complex periodic behavior and of quenching of simple oscillations.

We report sustained oscillations in glycolysis conducted in an open system (a continuous-flow, stirred tank reactor; CSTR) with inflow of yeast extract as well as glucose. Depending on the operating conditions, we observe simple or complex periodic oscillations or chaos. We report the response of the system to instantaneous additions of small amounts of several substrates as functions of the amount added and the phase of the addition. We simulate oscillations and perturbations by a kinetic model based on the mechanism of glycolysis in a CSTR. We find that the response to particular perturbations forms an efficient tool for elucidating the mechanism of biochemical oscillations.

Journal Article↗
PubMed1991

Analysis of the dynamics of relaxation type oscillation in glycolysis of yeast extracts.

In yeasts, the glycolysis may display oscillations of its metabolites while it is converting glucose. The dynamics of the oscillations has been investigated in cytoplasmic extracts of yeast under relaxation type conditions by determining the time course of some of the glycolytic metabolites. The compounds of the nucleotide pool have been identified as fast variables and the glucose derivatives as slow variables of the relaxation type. The period of oscillation has been subdivided into four phases which represent prominent parts of the limit cycle in the phase plane of a slow versus a fast variable. From the reaction processes in these phases, a dynamical picture of the mechanisms of oscillations is suggested. Accordingly, the oscillation results from an alternating activity of the fructose bisphosphate and the polysaccharide synthesis, both of which are coupled to glycolysis via the nucleotide pool. The processes in the phases are analyzed by calculating the rates of the reaction steps in the biochemical pathway.

Adenine Nucleotides↗
PubMed1990

Age-dependent proteins in eyes of annual killifishes Pterolebias longipinnis detected by 2-dimensional electrophoresis.

1. Eye proteins of Pterolebias longipinnis have been analyzed by 2-dimensional isoelectric focusing SDS-polyacrylamide gel electrophoresis during aging from adolescence until normal death. 2. The protein pattern on the gels changed gradually with progressing age. 3. In senescent eyes, three protein spots appeared for a time and 36 disappeared from the pattern. 4. The isoelectric points of the proteins in the presence of urea and the molecular weights in an unreducing buffer are presented.

Aging↗
PubMed1990

Region-specific expression in early chick and mouse embryos of Ghox-lab and Hox 1.6, vertebrate homeobox-containing genes related to Drosophila labial.

A chick gene homologous to the Drosophila homeobox gene labial has been cloned and sequenced. Regions of additional sequence identity outside of the homeobox reveal a close relationship to the mouse gene Hox 1.6. Northern blot analysis demonstrates that Ghox-lab and Hox 1.6 transcripts are both present at high levels during early stages of chick and mouse development, with a subsequent decline in abundance to very low levels by the time limb mesenchyme begins to differentiate. In situ hybridization analysis of chick embryos shows intense expression of Ghox-lab mRNA by Hamburger and Hamilton stage 4 (avian 'mid gastrula') and by stage 6 (pre-somitic neural plate) with expression decreasing shortly thereafter. The pattern of Ghox-lab RNA expression in these early embryos divides the embryo into an anterior and a posterior compartment. At stage 6, considerable signal is observed in the posterior two thirds of the embryo, while none is detected in the anterior third which is fated to become the head. This pattern is purely regional in nature, and does not follow boundaries defined by known tissue types. In situ hybridization of Hox 1.6 probes to mouse embryos of day 7.5 or 8.0 indicate that the Hox 1.6 transcript has a temporal and spatial distribution very similar to that of Ghox-lab in the chick embryo.

Amino Acid Sequence↗
PubMed1990

Light-driven diurnal zonation in the filamentous fungus Fusarium solani.

Zonation in growing mycelia of Fusarium solani was induced by diurnal light/dark cycles. Only those parts of the hyphae that grew in darkness for less than 20 hours developed a zone of conidia after illumination. In continuous darkness, in continuous illumination, or after a transition from light to darkness, a conidiation zone failed to appear. Only light periods exceeding a few seconds but lasting less than 21 hours during a 24 hour light/dark cycle induced zonation. This zonation was not caused by periodic staling of the growth medium.

Agar↗
PubMed1989

Circuit analysis of the oscillatory state in glycolysis.

The oscillatory state of glycolysis in yeast extracts has been analysed by methods known from electronic circuit studies. The time course of the reactions are calculated by the method of least squares from experimentally determined sets of the concentrations of most of the metabolites. The dynamics of the glycolytic network of reactions can then be represented in terms of flow versus driving force (current versus voltage in the corresponding electronic circuit). The analysis of the dynamics leads to the conclusion that glycolysis is switched on and off in a pulsed manner during the oscillatory state. The resulting pulsed flow cannot only be measured with glycolytic end products, like carbon dioxide or ethanol, but can also readily be demonstrated by diagrams of reaction rates of single enzymic steps even in the initial stages of the glycolytic sequence. An analytic method widely applied to electronic circuits also proved to be useful in the study of the dynamics of a complex enzymic network.

Data Interpretation, Statistical↗
PubMed1985

Long term oscillation in glycolysis.

To increase the period of glycolytic oscillations in yeast extracts (Saccharomyces uvarum), the dependence of the period on pH, on concentrations of phosphate and enzymes, and on temperature has been studied. Stable oscillatory trans were obtained at a pH value of about 6.5. Increasing the phosphate and decreasing the enzyme concentrations as well as decreasing temperature lengthened the period. By dilution of the extract with buffer while maintaining the metabolite concentrations at their initial level the period could be successively prolonged from 20 min to about 6 h.

Glycolysis↗
PubMed1984

Genome structure described by formal languages.

Nucleic acid sequences may be looked upon as words over the alphabet of nucleotides. Naturally occurring DNAs and RNAs form subsets of the set of all possible words. The use of formal languages is proposed to describe the structure of these subsets. Regular languages defined by finite automata are introduced to demonstrate the application of the concept on RNA-phages of group I. This approach permits a concise characterization of grammatical patterns in genetic information.

Base Sequence↗
PubMed1982

Spontaneous spatiotemporal organization in yeast extracts.

Stirred cytoplasmic extracts of the yeast Saccharomyces uvarum can, on addition of trehalose, display oscillations in the metabolite concentrations. Unstirred extracts may also develop spatiotemporal structures expressed in the metabolite concentrations. In this paper we present evidence of the existence of such patterns. The latter were recorded using the optical absorption of NADH in an annular cuvette, which was rotated in a photometer. Regularly spaced wavelike spatiotemporal standing waves were observed. At certain fixed points the NADH concentration appeared to remain constant. Such phenomena may improve our understanding of biochemical morphogenesis.

Glycolysis↗
PubMed1980

Spontaneous spatio-temporal organization in yeast cell suspension.

Under suitable conditions of substrate supply, cell suspensions of yeast Saccharomyces uvarum may display synchronized oscillations of glycolytic metabolism. Also in an unstirred suspension, spatial patterns can be induced by continuously feeding enzymically liberated glucose into the system. the absorption of NADH in the suspension was measured in an annular cuvette. The observed structures display moving waves, which travel over a distance of some centimetres in the cell suspension and seem to originate from a volume element in which the phase is ahead of those of its neighbours. The wavelength is estimated to be abot 10 cm and the velocity of spreading of the wave is about 5 cm/min. Waves are only observed in the beginning of glycolytic oscillations. Subsequently the spatial synchrony usually increases and destroys the previous organization. Similar spatio-temporal structures are observed during aggregation of the slime mould Dictyostelium discoideum and in the chemical reaction system of Belousov and Zhabotinsky.

Absorption↗
PubMed1976

Acid-base parameters and alveolar-arterial oxygen tension gradients in healthy neonatal and postneonatal infants.

In a randomly selected group of asymptomatic neonatal and postneonatal infants, acid-base parameters and oxygen tension measurements in arterial blood (radial artery) were carried out during air and oxygen breathing. Acid-base results showed a mild, partially compensated metabolic acidosis, indicating adequate pulmonary function. Arterial oxygen tension was in the normal range for this age group. Calculated alveolar oxygen tension levels demonstrated alveolar-arterial gradients of about 30 mm Hg during air breathing and 320 mm Hg during O2 breathing. Volumes of R-L shunts calculated from these gradients, were in the order of magnitude commonly found at this age, i.e., about 20% of right cardiac output. No differences were discernible between infants of appropriate weight for gestational age and small-for-date infants.

Acid-Base Equilibrium↗
PubMed1975

Transcutaneous determination of arterial oxygen tension.

Arterial oxygen tension measurements were performed simultaneously using two different techniques: (1) the conventional method of analyzing a blood sample obtained from the radial artery by means of a Clark electrode and (2) a new method of transcutaneous oxygen tension recording using a newly developed surface electrode containing a built-in heating device to ensure optimal cutaneous perfusion at the site of measurement. Two groups of newborn infants were used as subjects: (1) 70 clinically healthy babies who were tested during normoxia and hyperoxia (breathing 80% to 100% oxygen) and (2) 20 sick preterm and term infants receiving inspired oxygen concentrations of between 21% and 100% during the measurement. Our results indicate a satisfactory accuracy for the transcutaneous oxygen tension measurements in normoxia and hyperoxia (percentage coefficient of variation, 15.9% and 24.1%, respectively). In hypoxia agreement between the two methods varies depending on the degree of circulatory derangement. Overall correlation coefficients were greater than 0.85 in each group.

Blood Gas Analysis↗
PubMedDate not supplied

Oscillatory CO2 evolution in glycolysing yeast extracts.

The rate of formation of carbon dioxide in cytoplasmic yeast extracts in an open system with continuous infusion of glucose was measured by membrane inlet mass spectrometry during glycolytic oscillations. The rate of CO2 production rose in the first third of each cycle to a maximum of about 100 mumol per ml yeast extract per hour and subsequently diminished to a final level of about 50 mumol per h. Measurements of the NADH light absorption under the same conditions revealed oscillations of relaxation type. The phase of high CO2 production could be related to the phase of the high NADH level, giving evidence that the flux in glycolysis is increased during the phase of high NADH concentration. Only half of the amount of injected glucose was metabolized to CO2 during the sustained oscillation, although free glucose did not accumulate.

Carbon Dioxide↗