Cloning of the replication gene P of bacteriophage lambda: effects of increased P-protein synthesis on cellular and phage DNA replication

A restriction fragment of lambdaDNA carrying the P gene was cloned in the high copy number plasmid RSF2124. Cells harbouring this new plasmid RSF2124/lambdaE complement lambdaPam80 phage. A lac promoter-operator region (lacP), produced by EcoRI digestion of plasmid pKB252, was inserted into RSF2124/lambdaE such that induction of the lac promoter by IPTG or lactose leads to increased production of the P gene product. A high amount of P protein in E. coli cells results in a slow inhibition of bacterial DNA synthesis, suggesting that the initiation reaction is blocked by P protein. Synthesis of lambdaDNA proceeds normally under these conditions. Nonsuppressing groPA15 mutant bacteria which are unable to support the replication of wild-type lambda (lambdawt), acquire the ability to replicate lambdaPam80 phage but not lambdawt when they are transformed with a plasmid carrying the lambdaP gene. When harbouring a plasmid containing the mutant Pamber 80 gene, groPA15 mutants are able to support the replication of lambdawt phage when infected at a high multiplicity. lambdaPam80 phage does not multiply in these cells.

The influence of homologous plasma and fetal calf serum on human lymphocytic cortisol metabolism

The influence of a) tissue culture medium (RPMI), b) homologous plasma (HP), and c) fetal calf serum (FCS) on lymphocytic cortisol metabolism was compared to that of phosphate buffered saline alone. RPMI was found to enhance the conversion rate 1.71 times, whereas HP and FCS enhanced it about 3.2 times. Raising the temperature of the HP and FCS to 100 degrees C before incubation reduced the enhancing effect to the level of that obtained with RPMI.

Metabolism of cortisol by human thrombocytes

A study was made in order to see whether human thrombocytes are capable to metabolize cortisol. Known concentrations of thrombocytes were incubated with 1.23H-cortisol and the products isolated and identified by t.l.c., paper chromatography, and derivations. Two metabolites were found to be produced by thrombocytes: 20beta-hydroxycortisol and tetrahydrocortisol. The enzymatic nature of the reactions was proved by (1) heat treatment (2) finding out NADPH to be a specific cofactor and (3) the dependence of the activity on the number of thrombocytes in suspensions.

Middle-sized ninhydrin-positive molecules in uraemic patients treated by repeated haemodialysis. II. Chief peptide constituents of the faction

The fraction of middle-sized molecules obtained from haemodialysate by chromatography on Dowex 50W x 8 resolves upon thin-layer electrophoresis on Sephadex G-25 into nine ninhydrin-positive fractions and one staining only with tolidine reagent. All ten electrophoretic fractions give similar filtration profiles with Bio-Gel P-6 in the presence of SDS and 2-mercaptoethanol. The chief peptide components common to each electrophoretic fraction have molecular weight approx. 3000 and are especially abundant in lysine, glycine, glutamine acid and serine, while aromatic amino acids are in very low concentration.

Mycoplasma infection in pregnant rats: low viability of foetuses and newborn offspring

The controversy regarding the possible role of genital mycoplasma infection in human reproductive failure gave rise to a study in which pregnant rats, previously shown to be of normal fertility, were inoculated 7-11 days after conception with either Mycoplasma arthritidis or an equal volume of sterile broth medium. Repeated observations during the course of pregnancy revealed several pathogenic effects. A statistically significant decrease was observed in the mean litter size of infected mothers. Furthermore, the offspring showed low viability at birth and, still more, at 10 days after birth. Our data are compatible with the hypothesis that genital mycoplasma infection plays a role in reproductive failure.

A proposal for further modification of the phage-typing system for coagulase-negative staphylococci

Our phage-set, published in 1975 (6) was modified in that other staphylococcal hoststrains were found more suitable for the propagation. This new typing set of 15 phages should replace our old phage-sets. In comparing the phage-sets of Dr. Verhoef, Dr. Parisi and Dr. Blouse with our phages, the advantages of our new phage-set could be demonstrated. Lysogeny induction experiment with mitomycin C and UV-rays showed all staphylococcal host strains to be lysogenic. Conclusions of the studies performed were derived from and discussed.

Use of a phage set for the ecological typing of coagulase-negative staphylococci

The staphylococcal flora of skin and acne lesions of 98 patients was analysed by the use of phage typing and biotyping methods. It appeared that in some individuals a relatively stable staphylococcal flora was present while others harboured 7 or more different strains. The same S. epidermidis strains were found on different skin sites and in acne lesions of a given individual. Examples of different carriage patterns were given.

Cortisol metabolism in lymphocytes from cancer-bearing patients

A study was conducted to determine the pattern of cortisol metabolism by lymphocytes obtained from four groups of subjects: 27 male and female patients suffering from various types of malignancy other than malignancy of lymphatic tissues; and 26 healthy male and female controls. Known concentrations of cells were incubated with 1,2-3H-cortisol and the products were isolated by thin-layer and paper chromatography. Three metabolites were found to be produced by lymphocytes from both normal and cancer-bearing patients: 20alpha-hydroxycortisol, 20beta-hydroxycortisol, and tetrahydrocortisol. Cells from the female control group were found to be more active than those from the male controls, while cells from cancer-bearing patients were markedly more active than the normal cells, regardless of sex. It is suggested that this finding of increased metabolism of cortisol by lymphocytes from patients with different types of malignancy other than lymphoma may provide the basis for a new diagnostic aid.

Prevention of nitroprusside-induced cyanide toxicity with hydroxocobalamin

To investigate hydroxocobalamin's role in preventing cyanide intoxication from sodium nitroprusside, we studied two groups of patients. One group received nitroprusside alone, and the other received nitroprusside and hydroxocobalamin. Red-cell and plasma cyanide levels were 83.44 +/- 23.12 and 3.51 +/- 1.01 microgram per 100 ml after nitroprusside alone and were 33.18 +/- 17.29 and 2.18 +/- 0.65 microgram per 100 ml after nitroprusside plus hydroxocobalamin. Acidosis developed in patients with red-cell cyanide levels higher than 75 microgram per 100 ml. When hydroxocobalamin infusion was stopped before sodium nitroprusside infusion was discontinued, blood cyanide levels and base deficit increased in a manner similar to that in the untreated group. The dose of nitroprusside used in each group did not differ statistically. These data show that hydroxocobalamin prevents cyanide transfer from red cells and plasma to tissue after nitroprusside metabolism, and thereby prevents cyanide toxicity from large intravenous doses of the drug.

Roles of bacteriophage lambda gene products O and P during early and late phases of infection cycle

Ring-to-ring (early) replication of bacteriophage lambda DNA was blocked after heat inactivation of the P protein. Rolling circle (late) replication continued for several rounds at the rate reached when the temperature shift was carried out. The same differential effect was observed after inhibition of RNA or protein synthesis during the two different phases of replication. In contrast, inactivation of the O protein resulted in a fast stop of lambda DNA synthesis at early and late times after infection. The results were consistent with the following interpretations. (i) The lambda P gene product plays a role in the initiation of the ring-to-ring replication. (ii) Ring-to-ring replication continues parallel to rolling circle replication, possibly diminishing with time after infection. (iii) The O function is stable in and necessary for the structural integrity of an elongation complex. It is unstable in free form and probably released from such a replication complex after each round of replication at the ring-to-ring stage.

Initiation of lambda DNA replication in vitro promoted by isolated P-gene product

The product of the P gene of bacteriophage lambda was isolated from heat-induced lambda-lysogenic Escherichia coli cells. It was found to bind to DNA, to be devoid of nuclease activity acting on double-stranded lambda DNA and of nicking/closing activity. Initiation of lambda DNA replication promoted by the P-gene product in a complementation assay in vitro was sensitive to rifampicin. Sedimentation analysis of the products and their hybridization to separated lambda DNA strands indicate that lambda DNA was formed in a reaction similar to ring-to-ring replication in vivo. The reaction was symmetric from the beginning, i.e. both lambda DNA strands were copied without delay.

Macromolecular synthesis and energy level in a mitochondrial conditional yeast mutant, tsm-8

Mitochondrial DNA, protein and ATP syntheses persist at non-permissive temperature (35 degrees C) in the mitochondrial, conditionally rho- petites forming yeast mutant, tsm8. Protein and ATP syntheses, however, are diminished during prolonged incubation at 35 degrees C in non-fermentable substrate. Mitochondrial RNA synthesis decreases rapidly to a residual constant level of about 10% of the initial value after the shift to 35 degrees C. The decrease is reversed by returning to permissive conditions. Evidence is presented that this temperature-induced decrease in mitochondrial transcription rate is effected by a mutationally altered regulatory process rather than by temperature sensitivity of mitochondrial RNA polymerase. It is concluded that rho- petite formation in mutant tsm8 is not effected by complete inhibition of macromolecular and ATP syntheses but is correlated with a reduction in mitochondrial transcription.

Evaluation of a new bacteriophage set for typing of Staphylococcus epidermidis strains

A new set of typing phages was evaluated for typing 821 Staphylococcus epidermidis strains isolated from normal human skin and from acne lesions. This method was compared with two different systems for biochemical differentiation of S. epidermidis. Distinct subgroups of cocci, which differed in phage susceptibility as well as in biochemical properties, were found. A tentative subdivision of S. epidermidis strains by use of 16 phages arranged into four groups is proposed, together with additional biochemical differentiation of non-typable strains.

Polymyositis as a cause of malabsorption. A case report

We report on a patient with polymyositis which caused a malabsorption syndrome. The radiological findings included marked dilatation of the oesophagus and small intestine. The malabsorption syndrome appears to arise from bacterial overgrowth associated with intestinal stasis. The literature is reviewed. Polymyositis or dermatomyositis, like scleroderma, may involve the small bowel and cause the malabsorption syndrome.

The significance of fetal electrocardiography in the diagnosis of intrauterine bradyarrhythmia

From 11 cases of fetal bradycardia diagnosed by monitoring of 130 fetal electrocardiograms (ECG's) in high-risk pregnancies we have presented our experience in three selected cases of fetal bradyarrthythmia. Case 1 revealed on ECG blocked atrial premature beats simulating an extreme sinus bradycardia sequentially followed by conducted atrial premature beats. In case 2 we diagnosed ventricular premature beats in the form of persistent bigeminy which was controlled by intravenous propranolol. The last case illustrated the phenomenon of aberrant ventricular conduction known to occur in adult cardiology. The electrophysiologic basis of the variable arrhythmias was discussed. Detailed analysis of repeated direct fetal ECG's provided us with the diagnosis and understanding of the electrophysiologic mechanisms underlying the rhythm disturbances. This consequently determined the pharmacologic therapy and the obstetric approach relevant to each case. We have shown that by direct fetal electrocardiography it is possible to analyze accurately the rhythm disturbances. Persistent fetal bradycardia does not always signify fetal distress. We hope that this will lead to closer teamwork between the obstetrician and the cardiologist which will give an impetus to the future development of "fetal cardiology," thereby enhancing our understanding of the electrophysiology of the fetal heart.