Suppression of induction of SOS functions in an Escherichia coli tif-1 mutant by plasmid R100.1

The tif-1 mutation in the recA gene of Escherichia coli caused, at 40 degrees C, lethal cell filamentation, induction of the recA protein, mutagenesis, and, in lambda lysogens, prophage induction. The presence of plasmid R100.1 in tif-1 strains suppressed tif-mediated cell filamentation and killing, recA protein induction, and prophage induction in lysogens. It also reduced mutagenesis in a tif-1 sfiA11(R100.1) strain. Plasmids F'lac, P1, and pMB9, in contrast, had little or no effect on tif-mediated induction of lambda. The presence of R100.1 did not inhibit the induction of the recA protein or of lambda by ultraviolet irradiation or mitomycin C treatment of tif-1(R100.1) or tif-1(lambda)(R100.1) strains.

Suppression of tif-mediated induction of SOS functions in Escherichia coli by an altered dnaB protein

The tif-1 mutation in the Escherichia coli recA gene is known to cause induction of the various "SOS" functions at high temperature, including massive synthesis of the recA protein, lethal filamentation, elevated mutagenesis, and, in lambda lysogens, induction of prophage. It is shown here that the deoxyribonucleic acid initiation mutation dnaB252 suppresses all these manifestations of tif expression. Induction of lambda by ultraviolet irradiation, however, is not affected by the dnaB252 mutation. No similar suppression of tif is observed with other dnaB mutations affecting deoxyribonucleic acid elongation or with other deoxyribonucleic acid initiation mutations at the dnaA and dnaC loci. The fact that an alteration of the dnaB protein specifically suppresses tif-mediated SOS induction implies a role of the replication apparatus in this process, as has been suggested for ultraviolet induction. The induction of lambda is known to proceed via repressor cleavage, presumably promoted by an activated (protease) form of the recA protein. Since lambda induction is normal after ultraviolet irradiation of the tif-1 dnaB252(lambda) strain, tif-mediated induction in this strain may be blocked in a tif-specific step leading to activation of the recA (tif) protein. It is possible that the recA (tif) mutant protein may be directly involved in the replication complex in processes leading to this activation.

Reconstruction of the anterior talofibular ligament for the treatment of the unstable ankle

Chronic instability of the ankle is frequently due to disruption of the fibres of the anterior talofibular ligament and the anterolateral capsule. This allows momentary subluxations at the ankle joint; the talus tilts into an abnormal varus position and rotates forwards and inwards about a vertical axis which passes through the medial malleolus. The use of a free tendon graft to reconstruct the anterior talofibular ligament restores the stability of the ankle without restricting movement at the subtalar level.

Antibodies to galactocerebroside bind to oligodendroglia in suspension culture

Antisera raised in rabbits against galactocerebroside bind to bovine oligodendroglia in suspension in significant titer as demonstrated by indirect immunofluorescence. Absorption of antigalactocerebroside antiserum with galactocerebroside, oligodendroglia, or myelin markedly reduces the antigalactocerebroside antibody titer as measured by a radioimmunoprecipitation test as well as the binding to oligodendroglia. Incubation with some other galactose-containing glycolipids results in a parallel decrease in binding to oligodendroglia and reduction in antigalactocerebroside antibody titer. Antigalactocerebroside antibodies provide a useful and specific tool with which to study development of oligodendroglia and myelin as well as immunopathologic mechanisms which might be involved in demyelinating diseases.

Biospecific fractionation matrices for sequence specific endonucleases

Fractionation of several type II specific restriction endonucleases was achieved by separation on two novel biospecific matrices. The matrices are pyran, a copolymer of divinyl ether of maleic anhydride, and Cibacron Blue F3GA, a blue dye commonly used for the calibration of molecular sieves. Both compounds are insolubilized by coupling to sepharose through a cyanogen bromide linkage and in their soluble form inhibit the restriction endonucleases which we have tested. These affinity matrices can be used to obtain restriction endonucleases from crude extracts after removal of nucleic acids. They have also proven to have a high capacity when used as subsequent steps in enzyme purification. Their additional advantage is the rapid development time and reusability of columns packed with the two matrices.Images

MSH/ACTH 4-10 influences behavioral and physiological measures of attention

Eleven healthy male volunteers were infused with MSH/ACTH 4-10 and a control solution in a completely crossed and balanced procedure. Perception, attention and memory were tested as were heart rate and cephalic pulse amplitude in response to changes in the environment. Treatment of subjects with MSH/ACTH 4-10 raised their perceptual threshold for detection of simple stimuli and facilitated perceptual integration of patterned information. Administration of the heptapeptide improved the subjects' ability to discriminate tests of relevant from irrelevant information and augmented the heart-rate deceleratory response during presentation of novel stimuli. It was speculated that MSH/ACTH 4-10 has a predominant influence on attentional processes and that it may be uniquely coded for attentional/perceptual functioning.

A new approach in specific, active immunotherapy

A vaccinia virus-lysed autochthonous tumor cell vaccine (vaccinia oncolysate) is introduced as a new specific, active immunotherapeutic agent against human cancer. Mouse experiments showed the vaccine to be a safe and potent immune mechanism stimulator. Human experimentation was undertaken in the knowledge of relative safety of the components of the vaccine, i.e. vaccinia vaccine and lysed, autochthonous tumor cells. Vaccine-treated patients had advanced metastatic cancer but reacted to one or more common recall antigen skin tests. None of the 13 patients had untoward responses; 7/13 patients had classic delayed hypersensitivity reactions at the vaccine injection sites; and 2/7 patients with injection site reactions had significant reduction in tumor burden. These results indicate that this vaccine is a specific, active immune mechanism stimulator, and may prove to be a useful therapeutic agent in the treatment of human cancer.

Postural hypoxemia in quadriplegic patients

Quadriplegic patients frequently undergo unusual positional changes, including head-down tilt. To determine if hypoxemia develops in this position and whether it is related to the duration of quadriplegia, five patients were studied within 1 year of injury (group A) and five after 1 year from injury (group B). Arterial blood gases were obtained in the seated and 45-degree head-down position. Group A patients had a decrease in arterial partial pressure of oxygen in the head-down position (p less than 0.025), while group B patients did not (p greater than 0.4). This study demonstrated that quadriplegic patients have positional hypoxemia early in their course. This probably results from relative hypoventilation of the upper lung fields caused by flaccid paralysis of the intercostal muscles. The positional hypoxemia disappears with time, presumably because of the change from flaccid to spastic paralysis of the intercostal muscles.

Neuropeptide MSH/ACTH 4-10 enhances attention in the mentally retarded

Twenty adult mentally retarded men were randomly assigned to receive MSH/ACTH 4-10 or a vehicle control solution in a double blind procedure. After an intravenous injection the subjects were presented with an orienting sequence and a series of behavioral tests. Treatment with the peptide resulted in a significant decelerative heart rate response during the test stimulus of the orienting sequence. Improved performance of the intradimensional and extradimensional shift of a visual discrimination procedure was significant for subjects receiving MSH/ACTH 4-10. The pattern of response on the subproblem analysis of the extradimensional shift reflected greater dimensional attention in the subjects treated with the peptide. Attentive subjects given MSH/ACTH 4-10 evidenced significant improvement on a rhythm matching test, a test of spatial localization and a visual retention test. The data were interpreted as indicating that the peptide resulted in improved attention of stimulus processing. It was speculated that MSH/ACTH 4-10 may be unquely coded for perceptor/attentional functioning and may be useful as a treatment for disorders of attention.

Prophage induction and cell division in E. coli. III. Mutations sfiA and sfiB restore division in tif and lon strains and permit the expression of mutator properties of tif

In E. coli K12, cell filamentation promoted by tif is enhanced by the lon mutation; in contrast, prophage induction and repair of UV-irradiated phage lambda, also promoted by tif, are not affected by lon. From a tif lon double mutant, "revertants" having recovered the ability to divide at 41 degrees were isolated, among which most (95%) had also lost their Lon filamentous phenotype after ultraviolet (UV) irradiation. From these 95% of revertants: (1) 94% are suppressed for the whole Tif phenotype, by additional mutations that render them deficient in DNA repair, as judged from their high UV sensitivity; some have been characterized as recA mutants. (2) 1% have recovered a control on cell division at 41 degrees or after UV irradiation by means of secondary mutations altering neither the other phenotypic properties of tif and lon, nor the repair and recombination ability of the cells: in particular, this class of "revertants" remains thermoinducible upon lysogenisation; the mutations which specifically suppress filamentation have been mapped at two loci, sfiA and sfiB, cotransducible respectively with pyrD and leu. In the remaining 5% of revertants that still exhibit an UV-induced filamentous growth, 3% can be tentatively classified as true tif+ revertants; 2% behave as tif thermodependent revertants, showing suppression of the Tif (and Lon) phenotype only at 41 degrees: 2recAts have been identified in this class. Non-lysogenic tif lon sfi and tif sfi strains remain viable during prolonged growth at 41 degrees. Under these conditions, tif expresses mutator properties, which can be conveniently analyzed in this sfi background. The action of lif, lon and sfi mutations is tentatively interpreted on the basis of a negative control of cell division specifically associated with DNA repair.

Recovery of phage lambda from ultraviolet damage

Recovery of phage lambda from ultraviolet damage can occur, in the dark, through three types of repair processes as defined by microbiological tests: (1) host-cell reactivation, (2) prophage reactivation, and (3) UV reactivation. This paper reviews the properties of the three repair processes, analyzes their dependence on the functioning of bacterial and phase genes, and discusses their relationship. Progress in the understanding of the molecular mechanisms underlying the three repair processes has been relatively slow, particularly for UV reactivation. It has been shown that host-cell reactivation is due to pyrimidine dimer excision and that prophage reactivation is due to genetic recombination (prereplicative). We provide evidence showing that neither of these mechanisms accounts for UV reactivation of phage lambda. Furthermore, UV reactivation differs from the other repair processes in that it is inducible and error-prone. Whether UV-damaged bacterial DNA is subject to a similar repair process is still an open question.

In vitro repair of UV-irradiated Micrococcus luteus bacteriophage N1 transfecting DNA

Calcium-treated UV-sensitive, host cell reactivation(-) strains of Micrococcus luteus are infected with UV-irradiated N1 DNA. In strains lacking UV endonuclease, in vitro treatment of the irradiated DNA results in transfection enhancement.

Indirect ultraviolet-reactivation of phage lambda

When an F(-) recipient Escherichia coli K12 bacterium receives Hfr or F-lac(+) DNA from an ultraviolet-irradiated donor, its capacity to promote DNA repair and mutagenesis of ultraviolet-damaged phage lambda is substantially increased. We call this phenomenon indirect ultraviolet-reactivation, since its features are essentially the same as those of ultraviolet-reactivation; this repair process occurs in pyrimidine dimer excision-deficient strains and produces clear plaque mutations of the restored phage. Moreover, this process is similar to indirect ultraviolet-induction of prophage lambda, since it is promoted by conjugation. However, contrarily to indirect induction, it is produced by Hfr donors and occurs in recipients restricting the incoming ultraviolet-damaged donor DNA. The occurrence of indirect ultraviolet-reactivation provides evidence for the existence in E. coli of an inducible error-prone mechanism for the repair of DNA.

Increased growth hormone in partial and total lipoatrophy

Since some clinical and metabolic features of lipoatrophy suggest increased human growth hormone (HGH) activity, we studied HGH responses in five patients with partial or total lipoatrophy. Two patients with total lipoatrophy had elevated basal levels of HGH of 80 and 25 ng. per milliliter, while two with partial lipoatrophy had abnormally high levels after arginine stimulation. The elevated levels seemed to correlate with the clinical activity of the disease. In one of the patients there was a slowing of the growth rate and a moderate weight gain after long-term chlorpromazine therapy decreased HGH levels; a comparison of the immunoreactive HGH in her serum with that from a normal patient by serial dilution technics suggested that the two were immunologically identical, and chromatographic mobilities were also identical. Oral glucose suppressed elevated HGH in all of the patients. These studies suggest that HGH levels are elevated intermittently in lipoatrophic patients and that the increase may contribute to some features of the disease.