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Biomedical subjects

M Kessel

Publications and source records attributed to M Kessel.

At least 109 records · Page 6Linked to original sources
PubMed1984

An embryonal carcinoma cell line as a model system to study developmentally regulated genes during myogenesis.

We have established conditions to efficiently differentiate embryonic carcinoma stem cells of the line P19 into myogenic cells. As inducers for differentiation, a combination of embryoid body formation in conjunction with treatment with dimethyl sulfoxide and retinoic acid proved to be most efficient. Under these conditions we detected an accumulation of myosin- and actin-specific RNA. Also, large amounts of type IV collagen RNA were produced. Type IV collagen is a component of the muscle basement membrane. In analogy to the F-9 system, we found a drastic decrease in stable p53 mRNA under the differentiation conditions used.

Cell Line↗
PubMed1984

Time-resolved low-dose microscopy of glutamine synthetase molecules.

Time sequences of low-exposure images from the enzyme molecules of glutamine synthetase have been recorded digitally using an on-line recording system. Processing the images results in a time sequence of averaged molecule images, which, in the very beginning, exhibit the molecule structure still undamaged by electron irradiation. Different sources of the noise which obscures structural details, such as shot noise, stain embedding and radiation damage, are investigated.

Glutamate-Ammonia Ligase↗
PubMed1984

Kinetic interactions between azlocillin, cefotaxime, and cefotaxime metabolites in normal and impaired renal function.

Cefotaxime (CTX) kinetics, alone and in combination with azlocillin (AZ), were determined in 18 subjects with either normal or impaired renal function. After the single dose and with increasing renal insufficiency, total CTX clearance fell from 266 to 71 ml/min/1.73 m2. At the same time the terminal t1/2 rose from 1.1 to 2.8 hr. Regardless of the degree of renal function, CTX clearance in combination with AZ in all patients was only 50% to 60% of that with CTX alone. This reduction in total body clearance was due to a parallel decrease in renal and nonrenal clearance. In advanced renal failure, particularly after AZ, the terminal t1/2 of the CTX metabolites increased up to 1000% to 1500% of normal. On the basis of these findings, CTX dosage adjustment is recommended only in patients with a glomerular filtration rate (GFR) below 20 ml/min. After AZ, however, dosage reduction of CTX seems to be advisable at an earlier stage of renal impairment (GFR 40 ml/min).

Adult↗
PubMed1983

Electroencephalogram investigations of the disequilibrium syndrome during bicarbonate and acetate dialysis.

Continuous long-time electroencephalographic (EEG) monitoring was performed during acetate and bicarbonate dialysis in 20 patients. Persisting normal basic activity of the EEG without neurological symptoms was found only during the course of bicarbonate dialysis. However, in acetate dialysis, during the decrease of arterial CO2 tension (PaCO2), we registered EEG disturbances with moderate to severe slowing, dysrhythmic activity and high voltage discharges. The decrease in PaCO2 and the deterioration in EEG activity in the patients during acetate dialysis was concomitant with severe neurological alterations, e.g. the typical symptoms of so-called 'disequilibrium' causing a cessation of dialysis in three patients.

Acetates↗
PubMed1983

[Electro-encephalographic study of the disequilibrium syndrome during bicarbonate dialysis and acetate dialysis].

Continuous long-time electroencephalographic (EEG) monitoring was performed during AHD and BHD in 20 patients. Persisting normal basic activity of the EEG without neurological symptoms could be found only during the course of BHD. However, in AHD, during the decrease of arterial CO2 tension (PaCO2) we registered EEG disturbances with moderate to severe slowing down, dysrythmic activity and high voltage discharges. The decrease in PaCO2 and the deterioration in EEG activity in the patients during AHD was concomitant with severe neurological alterations, e.g. the typical symptoms of so-called "disequilibrium" causing a cessation of dialysis in 3 patients.

Acetates↗
PubMed1982

Advantages of bicarbonate hemodialysis.

Six patients with frequent episodes of symptomatic hypotension during acetate dialysis were treated with bicarbonate dialysis. In all patients blood pressure, heart rate, and arterial acid-base values were measured every 30 minutes during each of the five treatments with acetate dialysis and bicarbonate dialysis. Hemodynamic parameters were measured invasively in all patients during bicarbonate dialysis and in three of them also during acetate dialysis. Additionally, continuous long-time monitoring with electroencephalography was performed during acetate dialysis and bicarbonate dialysis. During acetate dialysis the patients showed a frequent onset of sudden hypotension and arrhythmia with concomitant symptoms of the so-called disequilibrium syndrome, whereas these symptoms were nonexistent in the same patients during bicarbonate dialysis.

Acetates↗
PubMed1982

Ultrastructure of square bacteria from a brine pool in Southern Sinai.

The square bacterium discovered by Walsby (Nature [London] 283:69-71, 1980) has been shown to possess the ultrastructural features of a typical halophile. The cell wall is comprised of regularly arranged subunits demonstrated by thin sectioning, shadowed replicas, and negative staining. Optical diffraction confirms the existence of both hexagonal and tetragonal arrangements of the cell wall subunits and also of different lattice constants and suggests a mixed population of bacteria.

Bacteria↗
PubMed1981

Protein losses during peritoneal dialysis.

The losses of protein into dialysate have been considered a major limitation of maintenance peritoneal dialysis. We, therefore, undertook a comprehensive evaluation of protein losses in 30 patients undergoing maintenance intermittent peritoneal dialysis (IPD), 12 patients undergoing acute IPD, and 8 patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The weekly loss of protein based upon the usual treatments per week was relatively similar with the three modes of dialysis. Protein losses during repeated dialyses were similar for a given patient, but there was repeated dialyses were similar for a given patient, but there was marked interpatient variation. During maintenance IPD, protein loss was 12.9 +/- (SD) 4.4 g per 10 hours of dialysis; albumin loss was 8.5 g, and IgG loss was 1.3 g. Approximately 50% of the protein loss was from the ascitic fluid accumulated during the interdialytic interval, and concentrations of most proteins in the ascitic fluid correlated with their serum levels. Serum protein concentrations were in the low, normal range and did not change during dialysis. The development of peritonitis markedly increased protein losses. During acute IPD, 23.3 +/- 16.5 g of protein were lost per 36 hours of dialysis, lower losses than those previously reported. With CAPD, 8.8 +/- 1.7 g of protein were removed per 24 hours; also immunoglobulin losses correlated with their serum concentrations. The results of these studies suggest that, in the absence of peritonitis, dialysate protein losses do not appear to limit the usefulness of peritoneal dialysis.

Adult↗
PubMed1981

Two elongation factors from the extremely halophilic archaebacterium Halobacterium cutirubrum. Assay systems and purification at high salt concentrations.

Two peptide chain elongation factors from Halobacterium cutirubrum were purified nearly to homogeneity. They were identified and characterized by three assay systems working at very high salt concentrations: poly(Phe) synthesis, GDP binding and ADP-ribosylation. The purification procedure consisted of Sepharose 4B chromatography with a decreasing ammonium sulfate gradient, gel filtration on Sephadex G-100 in the presence of (NH4)2SO4 and, for each of the two separated factors, an independent adsorption chromatography on hydroxyapatite. The factors were absolutely dependent on high salt concentrations for stability and activity. Both factors (I and II) complement each other to give fully active poly(Phe) synthesis, which is totally inhibited by puromycin and anisomycin. Factor I (Mr 51 000) is a major protein of the cell-free extract. It binds GDP, which can be displaced by GTP only to a small extent. The function of factor I in poly(Phe) synthesis is not impaired by high concentrations of kirromycin. The observed characteristics resemble partly those of prokaryotic EF-Tu and partly those of eukaryotic EF-1. Factor II (Mr 111 000) can be ADP-ribosylated by diphtheria toxin, and thus was identified as an EF-2-type elongation factor.

Guanosine Diphosphate↗