Leukocyte-derived inhibitory activity in patients with myelodysplastic syndrome

Leukocyte-derived inhibitory activity inhibiting the entry of normal progenitor cells of granulocytes and macrophages (CFU-GM) into the S-phase of a cell cycle was investigated in 16 patients with different forms of myelodysplastic syndrome (MDS). The presence of this inhibitory activity was analysed in medium conditioned with low-density cells obtained from peripheral blood of MDS patients. The inhibition rate was measured by 3H-thymidine suicide technique with subsequent cultivation of pretreated cells in semisolid agar medium. Low-density cells from MDS patients of various types were studied: from the twelve patients with refractory anaemia (RA or RAS) only three were positive, one patient with chronic myelomonocytic leukaemia (CMML) was negative while one patient with refractory anaemia with excess of blasts (RAEB) and two patients with RAEB in transformation (RAEB-T) were positive with respect of the described test. In two patients with RA, who underwent a long-term investigation, the production of leukocyte-derived inhibitory activity preceded the development of disease into RAEB or RAEB-T. In five positive cases, supernatants were incubated with antiserum against human placental ferritin; with one exception, the inhibitory activity was neutralized.     

Microinjection of normal cell extracts into Fanconi anemia fibroblasts corrects defective scheduled DNA synthesis recovery after 8-methoxypsoralen plus UVa treatment

Summary Fanconi anemia (FA) cells show an increased sensitivity to 8-methoxypsoralen (8-MOP) plus UVa treatment; after an initial reduction of their semiconservative DNA synthesis rate, they do not recover like normal cells. We microinjected extracts from normal cells into FA fibroblasts from complementation group A and determined semiconservative DNA synthesis rates by autoradiography; the hampered recovery phase was completely restored.The present data are part of M. Gök's thesis 1987 at the University of Heidelberg     

Left ventricular response to sublingual administration of nitroglycerin

The aim of this study was to investigate whether the rapid improvement of the clinical condition of patients after administration of nitroglycerin can be documented objectively using the apexcardiogram. The study was performed on 28 male patients with coronary heart disease whose clinical condition allowed us to perform the initial polygraphic examination during an attack of angina pectoris. The heart rate and three apexcardiographic indexes were determined from non-invasive polygraphic tracings. The first index was the a/H (ratio: amplitude of apexcardiographic "a" wave to total amplitude of apexcardiogram). The second and third were the velocity of the anterior left ventricular wall motion during both isovolumic contraction (VwmC) and isovolumic relaxation (VwmR) of the left ventricle. The mean differences from initial values were calculated after 2, 4, 6 and 10 min following administration of nitroglycerin. Significant changes already occurred during the second minute after administration of nitroglycerin. All parameters remained significantly changed up to the 10th minute after this treatment. According to our results, the cardiovascular response to sublingual administration of nitroglycerin can be objectively evaluated by apexcardiography.     

Conversion of disaccharides to 3-ketodisaccharides by nongrowing and immobilized cells ofAgrobacterium tumefaciens

High-performance liquid chromatography was used to estimate 3-ketolactose and 3-ketosucrose in cultures of agrobacteria. The activities of enzymes that convert the disaccharide substrate were evaluated during batch cultivation ofAgrobacterium tumefaciens on sucrose, maltose, and lactose. The highest activity of glucoside 3-dehydrogenase and a slight activity of disaccharide-hydrolyzing enzymes were found in cells grown on lactose. Nongrowing cells converted lactose to 3-ketolactose faster than immobilized cells did. Immobilization of cells into polysaccharide gels did not stabilize the activity of glucoside 3-dehydrogenase. Glutaraldehyde cross-linking of the cell content led to an inactivation of the respiratory chain but Fe³⁺ could be used as an electron acceptor. Cells treated with glutaraldehyde converted lactose faster than nongrowing ones but the activity of glucoside 3-dehydrogenase was not stable.     

Forming sparse representations by local anti-Hebbian learning

How does the brain form a useful representation of its environment? It is shown here that a layer of simple Hebbian units connected by modifiable anti-Hebbian feed-back connections can learn to code a set of patterns in such a way that statistical dependency between the elements of the representation is reduced, while information is preserved. The resulting code is sparse, which is favourable if it is to be used as input to a subsequent supervised associative layer. The operation of the network is demonstrated on two simple problems.     

Comparative 113Cd-n.m.r. studies on rabbit 113Cd7-, (Zn1,Cd6)- and partially metal-depleted 113Cd6-metallothionein-2a.

Rabbit 113Cd7-metallothionein-2a (MT) contains two metal-thiolate clusters of three (cluster B) and four (cluster A) metal ions. The 113Cd-n.m.r. spectrum of 113Cd6-MT, isolated from 113Cd7-MT upon treatment with EDTA, is similar to that of 113Cd7-MT, but the cluster B resonances are lower in intensity, suggesting its co-operative metal depletion. (Zn1,113Cd6)-MT, formed upon addition of the Zn(II) ions to 113Cd6-MT, shows 113Cd-n.m.r. features characteristic of cluster B populations containing both Cd(II) and Zn(II) ions. The overall intensity gain of the mixed cluster B resonances per Cd as to those in 113Cd6- and 113Cd7-MT suggests a stabilization effect of the bound Zn(II) ions upon the previously established intramolecular 113Cd exchange within this cluster.     

Immobilization of Escheria alcalescens cells with aspartate ammonia-lyase activity

Summary Immobilization of Escherichia alcalescens cells into genu-carrageenan gel for L-aspartic acid production was studied with respect to the optimized preparation of heterogenous biocatalyst /2.5–3.0% genu-carrageenan, 15% biomass, 50–55 °C, tannin added/.     

On-line parameter and state estimation of continuous cultivation by extended Kalman filter

Summary The on-line estimation of biomass concentration and of three variable parameters of the non-linear model of continuous cultivation by an extended Kalman filter is demonstrated. Yeast growth in aerobic conditions on an ethanol substrate is represented by an unstructured non-linear stochastic t-variant dynamic model. The filter algorithm uses easily accessible data concerning the input substrate concentration, its concentration in the fermentor and dilution rate, and estimates the biomass concentration, maximum specific growth rate, saturation constant and substrate yield coefficient. The microorganismCandida utilis, strain Vratimov, was cultivated on the ethanol substrate. The filter results obtained with the real data from one cultivation experiment are presented. The practical possibility of using this method for on-line estimation of biomass concentration, which is difficult to measure, is discussed.Nomenclature D dilution rate (h^-1) - DO₂ dissolved oxygen concentration (%) - E identity matrix - F Jacobi matrix of the deterministic part of the system equations g - g continuousn-vector non-linear real function - h m-vector non-linear real function - K Kalman filter gain matrix - K _S saturation constant (kgm^-3) - K_S expectation of the saturation constant estimate - M Jacobi matrix of the deterministic part of the measurement equations h - P(t₀) co-variance matrix of the initial values of the state - P(t_k/t_k) c-variance matrix of the error in (t _k|t _k) - P(t_k+1/t_k) co-variance matrix of the error in (t _k+1|t _k - Q co-variance matrix of the state noise - R co-variance matrix of the output noise - S substrate concentration (kgm^-3) - S _i input substrate concentration - t time - t _k discrete time instant with indexk=0, 1, 2,... - u(t) input vector - v(t_k) measurement (output) noise sequence - w(t) n-vector white Gaussian random process - x(t₀) initial state of the system - (t₀) expectation of the initial state values - x(t) n-dimensional state vector - x(t_k) state vector at the time instantt _k - (t_k|t_k) expectation of the state estimate at timet _k when measurements are known to the timet _k - (t_k+1|t_k) expectation of the state prediction - X biomass concentration (kgm^-3) - expectation of the biomass concentration estimate - y(t_k) m-dimensional output vector at the time instantt _k - Y _XIS substrate yield coefficient - _X|S expectation of the substrate yield coefficient estimate - specific growth rate (h^-1) - _M maximum specific growth rate (h^-1) - expectation of the maximum specific growth rate estimate - state transition matrix