Methylglyoxal-mediated growth inhibition in an Escherichia coli cAMP receptor protein mutant

Under certain growth conditions, some strains of Escherichia coli accumulate toxic levels of methylglyoxal. This report characterizes a strain which synthesizes a mutant cAMP receptor protein in an adenylate cyclase deletion background. When cultured in glucose 6-phosphate minimal medium, this strain (222) was prematurely growth arrested due to methylglyoxal production; growth inhibition did not occur when the strain was grown in glucose minimal medium. A comparison of a variety of enzyme and cofactor levels in the related strains 222 (mutant) and 225 (wild-type) grown on either glucose or glucose 6-phosphate medium was carried out. The only difference found that might explain an increase in methylglyoxal accumulation was an elevated level of phosphofructokinase in strain 222 grown on glucose 6-phosphate. Since this enzyme activity probably limits hexose phosphate metabolism, it is suggested that growth inhibition in strain 222 may be due to increased production of triose phosphate, some of which is converted to methylglyoxal.     

DNA sequences which support activities of the bacteriophage phi X174 gene A protein

The DNA sequence of 30 nucleotides which surrounds the origin of viral strand DNA replication is highly conserved amongst the icosahedral single-stranded DNA bacteriophages. The A gene of these phages encodes a protein which is required for initiation and termination of viral strand DNA synthesis and acts as a nicking-closing activity specifically within this 30-nucleotide sequence. A system of purified Escherichia coli host proteins and phi X174 gene A protein has been developed which specifically replicates in vitro the viral strand of phi X174 from RF (replicative form) I template DNA and yields single-stranded circular DNA products (RF leads to SS(c) DNA replication system). Recombinant plasmids carrying inserts derived from phage phi X174 or G4 DNA which range in length from 49 to 1175 base pairs and contain the 30-nucleotide conserved sequence have been shown to support phi X A protein-dependent DNA synthesis in vitro in this replication system. We report here that insertion of the 30-nucleotide sequence alone into pBR322 allows the resulting recombinant plasmids to support phi X A protein-dependent in vitro DNA synthesis as efficiently as phi X174 template DNA in the RF leads to SS(c) replication system. The 30-nucleotide sequence functions as a fully wild type DNA replication origin as determined by the rate of DNA synthesis and the structure of resulting DNA products. Furthermore, the DNA sequence requirements for nicking of RF I DNA by the phi X A protein and for supporting replication origin function have been partially separated. Homology to positions 1, 29, and 30 of the 30-nucleotide conserved sequence are not required for cleavage of RF I DNA by the A protein; homology to position 1 but not 29 or 30 is required for efficient DNA replication.     

Enzymatic deconjugation of catecholamines in human and rat plasma and red blood cell lysate

We have developed a method for enzymatic hydrolysis of both sulfated and glucuronidated catecholamines in plasma and red blood cell lysate. Hydrolysis occurs in the course of the radioenzymatic assay for catecholamines. In human plasma, catecholamines are conjugated almost entirely with sulfate while, in rat plasma, glucuronides are the main conjugates of epinephrine and dopamine but not norepinephrine. Rat plasma contains less percent conjugated catecholamine than human plasma. Human red blood cell lysate contains less conjugated catecholamine than plasma, whereas free E in lysate exceeds that of plasma and free NE has same level both in plasma and lysate. This method is useful in detecting total (free + sulfated + glucuronidated) catecholamines and the nature of conjugated catecholamines.     

Congenital nevocellular nevus: a review of the treatment controversy and a report of 46 cases

Because congenital nevocellular nevi can be distinguished clinically and histologically from acquired nevi, and because of their apparent increased potential for malignant degeneration, we favor complete one-stage excision of these nevi, regardless of the size of the lesion or the age of the patient, at the earliest opportunity, whenever such surgery is feasible and practical. If there is a question about the clinical diagnosis, a cutaneous punch biopsy can help determine the true nature of the lesion. Significantly, Walton et al. and Rhodes and coworkers found discrepancies in the literature concerning the level of nevus cells in neonates. They concluded that until these differences are reconciled, nevus cells in the deep reticular dermal collagen may be a sufficient, but not a necessary criterion for the diagnosis of congenital melanocytic nevus. We currently favor complete one-stage excision of congenital nevocellular nevi and feel that treatment by tangential excision or dermabrasion require further study. Finally, we present this paper as "advice" not only to the three authors who, in a recent issue of the British Journal of Plastic Surgery, requested it, but also to all clinicians. Hopefully, with time and further study, better criteria will be determined and a more definitive approach to this problem will be established.     

Specific and nonspecific T-cell recruitment in viral meningitis: Possible implications for autoimmunity

Specific and nonspecific T-cell invasion into cerebrospinal fluid has been investigated in the nonfatal viral meningoencephalitis induced by intracerebral inoculation of mice with vaccinia virus. At the peak of the inflammatory process on Day 7 approximately 5 to 10% of the Lyt 2⁺ T cells present are apparently specific for vaccinia virus. Concurrently, in mice primed previously with influenza virus, 0.5 to 1.0% of the appropriate T-cell set located in cerebrospinal fluid is reactive to influenza-infected target cells. This vaccinia virus-induced inflammatory exudate may thus contain as many as 500 influenza-immune memory T cells. These findings are discussed from the aspect that such nonspecific T-cell invasion into the central nervous system during aseptic viral meningitis could result in exposure of potentially brain-reactive T cells to central nervous system components.     

Gallium-67 Scans in the Diagnosis of Pyelonephritis

Gallium-67 (⁶⁷Ga) citrate was administered intravenously (50 microcuries per kg of body weight) to patients in whom acute and chronic urinary tract infections were suspected. Scanning was done, using both the Anger-type scintillation camera and the rectilinear scanner, 24 to 78 hours after injection of the isotope.The preliminary results imply that ⁶⁷Ga renal uptake is present in patients with pyelonephritis whether overt or silent, as well as in patients with uretero-sigmoidostomies. However, ⁶⁷Ga renal uptake is not present in patients with radiographic evidence of chronic pyelonephritis without active infection and in patients without renal disease.     

Time-Lapse Cinemicrographic Studies of X-Irradiated HeLa S3 Cells: II. Cell Fusion

Analysis of time-lapse cinemicrographs of X-irradiated HeLa S3 cells has shown that the incidence of cell fusion was increased from 0.9% (following 1267 divisions) in control cells to an average of 22% (following 655 divisions) in cells irradiated with 500 rad doses of 220 kv X-rays. The incidence depended on the stage of the generation cycle at which the parent cells were irradiated. It was nearly constant in the first three postirradiation generations. Fusion occurred at all stages of the generation cycle, but preferentially during the first 20%. Cells undergoing fusion progressed more slowly through the generation cycle and had a higher probability of disintegrating than did irradiated cells that did not fuse. The occurrence of fusion was clonally distributed in the population. It took place only between sister (or closely related) cells. Protoplasmic bridges were often visible between sister cells prior to fusion. Giant cells arose only as a result of fusion. The incidence of multipolar divisions, though higher than in unirradiated cells, was only 5.5% in cultures irradiated with 500 rads. Fusion occurred following 85% of the multipolar divisions and was often followed by a multipolar division.