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Biomedical subjects

R Janzen

Publications and source records attributed to R Janzen.

At least 19 recordsLinked to original sources
PubMed1990

[Mixed venous versus central venous oxygen saturation in intensive medicine].

Mixed venous oxygen saturation (SvO2) has been established as a useful guide in observing whole body oxygenation. Since SvO2 provides limited information about adequate tissue oxygenation for a specific organ, the usefulness of central venous saturation (ScvO2) as a guide was analysed, which is a less invasive parameter. In 19 ICU patients 44 pairs of blood samples were drawn from a separate central venous catheter and from the tip of an SG-catheter. The correlation of oxygen partial pressures was 0.687 and the correlation of the saturation reached 0.779. The calculation of venous admixture showed a correlation of 0.901. It is concluded that ScvO2 yields adequate information on the oxygen saturation of venous return.

Catheterization, Central Venous↗
PubMed1987

Evaluation of advanced silica packings for the separation of biopolymers by high-performance liquid chromatography. III. Retention and selectivity of proteins and peptides in gradient elution on non-porous monodisperse 1.5-microns reversed-phase silicas.

Following previous studies of the use of non-porous monodisperse 1.5-microns n-octyl- and n-octadecyl-bonded silicas in gradient elution of proteins, this work was aimed at elucidating further the properties of this novel column material for peptide and protein separations in comparison with wide-pore silicas. First, it is demonstrated that with short columns (e.g., 35 X 8 mm I.D.) packed with these non-porous reversed-phase materials, mixtures of small peptides and mixtures of proteins can be very efficiently resolved. When the chain length of the bonded ligand was varied, the retention of a test set of proteins in gradient elution followed the ligand sequence C18 greater than C8 approximately C4 approximately phenyl greater than C2 under constant elution conditions, and the selectivity remained unchanged. Comparison of the S values of these proteins, as determined from evaluation of the log k' vs. phi dependences with non-porous silicas and with a LiChrospher Si 1000 C8 with identical accessible ligand surface areas per unit column volume, indicated lower values for the non-porous materials (k' = capacity factor; phi = molar fraction of organic solvent; S = slope of the plot of log k' vs. phi). The origin of this behaviour is discussed.

Caseins↗
PubMed1987

Evaluation of advanced silica packings for the separation of biopolymers by high-performance liquid chromatography. IV. Mobile phase and surface-mediated effects on recovery of native proteins in gradient elution on non-porous, monodisperse 1.5-microns reversed-phase silicas.

The reversed-phase chromatography of proteins by gradient elution with acidic, low-ionic-strength aqueous-organic eluents is often associated with losses of the biological activity of the protein. In this study, the enzymatic activities of catalase, horseradish peroxidase and pepsin were examined under static and dynamic column conditions on non-porous, monodisperse 1.5-microns reversed-phase silicas with various n-alkyl ligands. Catalase readily lost its enzymatic activity under the influence of the acidic aqueous-organic eluents in the absence of the reversed-phase packing, whereas peroxidase was partially deactivated as a result of combined mobile phase and stationary phase effects but regained its activity on storage after elution. The enzymatic activity of pepsin was found to be very dependent on the column residence time and on the type of bonded n-alkyl ligand employed.

Catalase↗
PubMed1987

Evaluation of advanced silica packings for the separation of biopolymers by high-performance liquid chromatography. V. Performance of non-porous monodisperse 1.5-microns bonded silicas in the separation of proteins by hydrophobic-interaction chromatography.

Non-porous monodisperse 1.5-microns silicas were allowed to react with (A) and (B) N-acetylaminopropyltriethoxysilane to generate bonded phases useful in high-performance hydrophobic-interaction chromatography (HIC). Differences in the selectivity were observed between the amide and the ether phase. Peak capacities between 10 and 30 were achieved for several proteins with the amide and ether phase packed into columns of 36 X 8 mm I.D. and elution of the proteins under chromatographic conditions in which the gradient volume, VG, was held constant by varying the gradient time between 20 and 2.5 min and the flow-rate between 0.5 and 4.0 ml/min. The S values derived from the dependences of log k' on the volume fraction of the low ionic strength buffer, phi b, were of the same magnitude as reported for porous HIC silicas and showed a dependence on the molecular weight of the protein. Using these HIC stationary phases based on non-porous 1.5-microns supports, fast separations (less than 5 min) could be carried out with high biological recoveries.

Ammonium Sulfate↗
PubMed1987

The acute phase response to inflammation: the role of monokines in changes in liver glycoproteins and enzymes of glycoprotein metabolism.

The role of monocyte derived factors in the acute phase response to inflammation is discussed. The kinetics of response of alpha 1-acid glycoprotein, sialyltransferase and albumin to a rat monokine preparation is described. There was an increase in synthesis of alpha 1-acid glycoprotein and sialyltransferase and a decrease in albumin synthesis following administration. However, the kinetics of response of sialyltransferase to the monokine was much slower than was found for the other two proteins. The possibility that sialyltransferase responds to a different monokine compared to the other acute phase proteins is discussed.

Acute-Phase Reaction↗
PubMed1987

Studies on the effect of inflammation on the acute phase response using rat liver slices.

Liver slices from control and inflamed rats were incubated in McCoy's medium and incorporation of [3H]leucine into liver and medium proteins and into albumin and alpha 1-acid glycoprotein was monitored over 48 hr. The release of the new acute phase reactant, sialyltransferase was also monitored in this system. Earlier observations in which liver slices were incubated for 6 hr showed that increased leucine incorporation into liver and medium proteins and alpha 1-acid glycoprotein, coupled with decreased incorporation into albumin, correlated with the acute phase response of these proteins. Increased incorporation of leucine into these proteins was found following 48 hr incubation in McCoy's medium showing that slices were able to express the changes characteristic of the acute phase response over this longer time period of incubation. Sialyltransferase was released into medium in a linear fashion up to 15 hr and continued to increase for 30 hr in this system; there was a substantial increase in release of enzyme activity from slices from inflamed rats when compared to controls. Monokine-conditioned medium prepared from peritoneal exudate cells isolated from rats at various times after lipopolysaccharide administration was used to induce the acute phase response by intraperitoneal injection. Slices were prepared from these rats and sialyltransferase release from slices was monitored. Monokines prepared from peritoneal exudate cells isolated from rats at about 30 hr were most effective in stimulating sialyltransferase release from liver slices.

Acute-Phase Reaction↗
PubMed1986

Packings and stationary phases in preparative column liquid chromatography.

Although the theoretical treatment of chromatographic processes on a preparative scale provides guidelines to the extent to which packing and stationary phase properties affect the target quantities such as sample input, throughput and resolution times sample input, a series of additional criteria were established to judge the quality of a packing in preparative column liquid chromatography. These include bed stability and flow resistance, chemical resistance and purity, solute accessibility, mass and biological recovery, fouling, regeneration and cost. Applying these criteria, the relative importance of physical and chemical structure parameters of packings and stationary phases was assessed. Commercial packings with mean particle diameters dp greater than 20 micron were listed for adsorption, size exclusion, ion-exchange and affinity chromatography. An analysis of the characteristic features of phase systems showed that adsorption media offer a high selectivity combined with adequate loadability, whereas ion exchangers and affinity media were best suited for biospecific solutes, particularly biopolymers, which can be attributed to their high selectivity and loadability.

Chemical Phenomena↗
PubMed1979

[Neurological cardinal symptoms of internal diseases (author's transl)].

The old rule:"Frequent is frequent, Seldom is seldom" is only true of etiological entities. With symptoms and syndromes which are hastily diagnosed as "typical" or "atypical" just because they are frequent, serious misdiagnoses may occur and critical details both in the history and in the physical examination may be overlooked. The terminal reaction of the body, i. e. the phenomenological entities are a principium cognoscendi for the doctor as for the patient they are principium agendi which send him to the doctor. The task of the neurologist is to set out the neurological cardinal and warning symptoms as signposts for a satisfactory internist investigation and to a jointly controlled therapy.

Brain Diseases↗
PubMed1976

Disparity between clinical and immune responses in a controlled trial of azathioprine in rheumatoid arthritis.

Drugs that interfere with the immune response in vitro, such as azathioprine (AZ), have been used extensively since 1964 in clinical therapeutic trials of autoimmune diseases. However, few adequately controlled studies are available concerning the concurrent effect of AZ on the immune and clinical responses to treatment of rheumatoid arthritis (RA). Thirty patients suffering from classical seropositive RA received AZ (1.5 - 2.0 mg/kg/day) and placebo in a controlled clinical cross-over study for two 12-week periods. Other treatments were kept constant throughout the entire 6 months. In terms of the clinical responses of joint count and grip strength patients receiving AZ improved markedly, in contrast to the placebo group. After 2 months, joint scanning revealed no progress of the disease in patients undergoing AZ treatment. Corresponding with the remarkably beneficial clinical effect of AZ, a significant drop in immunoglobulins was observed. However, since AZ failed to suppress in vivo specific antibody synthesis in RA, the question remains as to whether this drug actually does interfere with the autoimmunogenesis of the disease.

Adult↗
PubMed1975

Haemolytic anaemia with hereditary pyruvate kinase instability developing acute leukaemia.

The case of a 27-year-old woman with pancytopenia, revealing acute monocytic leukaemia and haemolytic anaemia, is described in detail. The underlying cause for the red cell destruction was found to be a pyruvate kinase (PK) instability. Further investigation into three generations of her family (n = 12) disclosed a hereditary PK instability. This was proven by performing biochemical studies to elucidate mutants representing a structurally defective enzyme. Since conversions of pancytopenia with acquired red cell enzyme deficiency into leukaemia have been described, our observation emphasizes that hereditary red cell enzymopathy might also be associated with adult acute leukaemia.

Adenosine Triphosphate↗