Mössbauer effect and electron paramagnetic resonance studies on yeast aconitase

Mössbauer effect and electron paramagnetic resonance (EPR) were measured for yeast aconitase [EC 4.2.1.3] purified from the cells of Candida lipolytica (ATCC 200114). Mössbauer spectra suggested that yeast aconitase nostly contained two high-spin Fe(III) ions in an antiferromagnetically coupled binuclear complex that resembled oxidized 2 Fe ferredoxins, together with a small amount of high-spin Fe(II). EPR spectra recorded no signal at 77degreesK, but showed a slightly asymmetric signal centered at g=2.0 at 4.2degreesK, presumably due to the small amount of Fe(II) Fe(III) pairs.

Bacteriophage phi X174 DNA synthesis in Escherichia coli HF4704S (dnaHts) cells

The DNA synthesis of bacteriophage phiX174 in Escherichia coli HF470S, a mutant temperature sensitive in the initiation of DNA replication (dnaHts), has been examined. In HF4704S cells, phiX174 can grow normally at 27 degree C whereas the phage cannot grow after the cessation of DNA synthesis of the host cells at 42 degrees C. Upon infection, phiX174 DNA can be injected into the host cell and the parental replicative form can be formed, but the progency replicative form cannot be synthesized at 43 degrees C in the absence of host DNA synthesis. The progency replicative form cannot be synthesized at 27 degrees C in the presence of 30 mug chloramphenicol/ml in the host cell which has been incubated for 74 min at 43 degrees C followed by transfer to 27 degrees C in the presence of 30 mug chloramphenicol/ml. When 30 mug chloramphenicol/ml is added later than 5 min after the temperature shift-down to 27 degrees C, the progency replicative form synthesis is not inhibited. Thus, the host cell function, for which the gene dnaH is responsible, has been shown to be essential to the progency replicative form production.

Lymphoid response of the burn patient

Clinical observations have long suggested immunologic compromise in burned patients. Resolution of the immune system into cooperative dual components of T-cells mediating delayed hypersensitivity and B-cells mediating antibody responses prompted the present survey of T-cell and B-cell changes after acute thermal burn injury. Adults and children sustaining extensive burn injuries were studied for up to 60 days after injury. T-cell function was assessed by lymphocyte counts, in vitro lymphocyte synthesis of RNA and DNA with and without mitogenic stimulation, and lymphocyte response and stimulatory capacities in the mixed lymphocyte culture (MLC) reaction. B-cell function was studied by quantitation of the major classes of circulating immunoglobulins. Transient lymphocytopenia, increased RNA and DNA synthesis rates by both mitogenstimulated and unstimulated lymphocytes, and impairment of lymphocyte response and stimulation in the MLC were observed early in the postburn period. These parameters tended to normalize by the third week after injury. Immunoglobulin levels, particularly IgG, were depressed significantly the first week postburn, but were normal or elevated by 60 days. These studies document both T-cell and B-cell changes postburn,which appear to be reversible with the recovery phase. A transient shift of circulating lymphocytes toward the B-cell type is suggested and early depression of immunoglobulin levels is notable. Both types of changes likely contribute to the immunologic compromise of the acutely burned patient.

[RI-cisternography of traumatic pneumocephalus (author's transl)]

A radionuclide, when injected intrathecally, normally does not enter into the ventricle system. In our three cases of intra cerebral-ventricular pneumocephalus the radionuclide entered into the ventricle and concentrated in the cyst. Such an abnormal movement of the radionuclide was generally caused by the obstruction of subarachnoid space and the increased C.S.F. absorption in the enlarged ventricle. Under consideration of the pre-and post-operative cisternograms of our three cases we examined the principal factor which brought on the abnormal movement of a radionuclide. Each principal factor was the excessive C.S.F. rhinorrohea in the first case, the increased C.S.F. absorption in the enlarged ventricle and the cyst in the third case. An analysis of our three cases shows that the accumulation of radionuclide into the ventricle system is not necessarily due to the obstruction of subarachnoid space, but also due to more C.S.F. absorption in the ventricle system than that in the subarachnoid space.

Effects on radioimmunoassay of digoxin of varying incubation periods for antigen---antibody reaction and varying periods of absorption by dextran-coated charcoal

In radioimmunoassay of digoxin by the dextran-coated charcoal method, duration of the incubation period for the antigen-antibody reaction and time allowed for dextran-coated charcoal to absorb the free antigen are critical factors. We compared effects of prolonged periods of absorption on results obtained with five commercial kits. In all cases, the digoxin concentrations increased linearly with absorption time, but the increase varied among kits. Kallestad and New England Nuclear 3h-kits and the Squibb 125I-kit showed less increase (i.e., gave relatively consistent results after various periods of absorption); the Schwarz/Mann 125i-kit and Clinical Assays 3h-kit showed greater increases. Precautionary steps are outlined for radioimmunoassays by this technique.

Idiopathic (asymptomatic) monoclonal gammopathies

Asymptomatic forms of monoclonal gammopathies (MG) are recognized with increasing frequency; their recognition and differentiation from the symptomatic forms of MG appear imperative, since the therapeutic approaches are different. Available clinical and laboratory indexes lack specificity required for useful and practical discrimination; presently, we must still rely on the timecourse monitoring of such laboratory values as hemoglobin levels, M-protein concentrations, and presence of Bence Jones proteins. Elucidation of histocompatibility A and W antigenic profiles, as well as the functions and kinetics of B-lymphocytes from such patients, appear most promising. Evidence of the causative role of extrinsic and intrinsic antigenic stimulation in MG production is increasing; segregation into two distinct concentration ranges of M-proteins in the asymptomatic and symptomatic groups suggests two control levels of the expression of immune response (Ir) genes, due to partial or complete derepression of the latent Ir gene function, reflecting "partial" (asymptomatic, benign MG) and "complete" (symptomatic, malignant MG) monoclonal immune responders.

Electrophoretic separation of tubulin alpha and beta subunits after S-sulfonation

The modification of tubulin cystine and cystine residues to S-sulfocysteines caused a distinct separation of the alpha and beta subunits in a continuous sodium dodecyl sulfate polyacrylamide gel system. The well-separated subunit bands permitted investigation of the phosphorylation of alpha and beta tubulin subunits. The incubation of tubulin fraction with [gamma-32P]ATP demonstrated that both subunits were phosphorylated in vitro. The incorporation of 32-PO4 into sea urchin eggs, however, failed to cause phosphorylation of tubulin in vivo.

Replication of deoxyribonucleic acid in Escherichia coli C mutants temperature sensitive in the initiation of chromosome replication

An Escherichia coli HF4704S mutant temperature sensitive in deoxyribonucleic acid (DNA) synthesis and different from any previously characterized mutant was isolated. The mutated gene in this strain was designated dnaH. The mutant could grow normally at 27 C but not at 43 C, and DNA synthesis continued for an hour at a decreasing rate and then ceased. After temperature shift-up, the increased amount of DNA was 40 to 50%. When the culture was incubated at 43 C for 70 min and then transferred to 27 C, DNA synthesis resumed after about 50 min, initiating synchronously at a fixed region on the bacterial chromosome. The initiation step in DNA replication sensitive to 30 mug of chloramphenicol per ml occurs synchronously before the resumption of DNA replication after the temperature shift-down, being completed about 30 min before the start of DNA replication. When the cells incubated at 27 C in the presence of 30 mug of chloramphenicol per ml after the temperature shift-down to 27 C were transferred to 43 C with simultaneous removal of the antibiotic, no resumption of DNA replication was observed. When the culture was returned to 43 C after being released from high-temperature inhibition at 30 min before the start of DNA replication, no recovery replication was observed; whereas at 20 min, the recovery of replication was observed. These results indicated that HF4704S was temperature sensitive in the initiation of DNA replication. Analysis of HF4704S, by an interrupted conjugation experiment, indicated that gene dnaH was located at about 64 min on the E. coli C linkage map. In E. coli S1814 (a K-12 derivative), which was a dnaH(ts) transductant from HF4704S (C strain) with phage P1, the mutated gene (dnaH) was demonstrated to be closely linked to the thyA marker by conjugation and P1 transduction experiments and to be distinct from genes dnaA through dnaG.

In vitro reactivity of human lymphocytes in chronic uraemia: analysis and interpretation

Altered cellular immunity complicating chronic uraemia includes lymphocytopenia, thymic atrophy, impaired allograft rejection and delayed hypersensitivity in skin tests, diminished appearances of lymphocytes on skin windows, and shortened in vitro survival of uraemic lymphocytes. Studies were undertaken to further characterize these lymphocyte defects.

Lymphocytes separated from peripheral blood of twenty-four uraemic patients were compared with those from fifty-one normal persons in their rates of RNA and DNA synthesis in both PHA-stimulated and unstimulated cultures, as determined by incorporation of radiolabelled precursors. Synthesis, expressed as absolute incorporation/10⁶ viable lymphocytes, was accelerated in the majority of both stimulated and unstimulated uraemic cultures. Serial studies over several months of twenty-five uraemic patients (fifteen maintained by haemodialysis, ten by renal allotransplantation), compared with nineteen normal controls, showed these differences to be consistent and persistent. While normal lymphocytes exhibited stability, uraemic cells fluctuated widely in their serial synthesis rates. In 25% of such cultures, unstimulated synthesis exceeded that induced by PHA. Increased synthesis without PHA, reflecting enhanced spontaneous blastogenesis, is compatible with decreased survival, numbers, and functional capacity of uraemic lymphocytes.

Reports by others of diminished PHA-responsiveness of uraemic lymphocytes are based upon whole-culture incorporation and/or expressed as ratios between stimulated and unstimulated cultures. Both shortened survival and accelerated spontaneous nucleic acid synthesis by uraemic lymphocytes cause such ratios to be misleadingly low. Such factors as cell numbers and viability at harvest, counting efficiency, and culture sterility are essential to avoid misinterpretations of such data based on incorporation of radiolabelled precursors to the nucleic acids.