T-T cyclobutane dimers are misinstructive, rather than non-instructive, mutagenic lesions.

The lesions produced by SOS-dependent mutagens in Escherichia coli are commonly referred to as nonpairing or non-instructive. Although these terms are likely to be appropriate for some lesions, particularly the abasic site, for others, such as the cyclobutane dimer, their suitability is open to question. To address this question, we have compared the error frequencies and spectra that result when a uniquely located T-T sequence, carried in a single-stranded vector, contains either a cis-syn or a trans-syn cyclobutane dimer, or when either the 5'T or 3'T is converted to an abasic site.

Mutation frequency and spectrum resulting from a single abasic site in a single-stranded vector.

We have investigated the mutagenic properties of an abasic site in DNA by transfecting SOS-induced and uninduced cells of E. coli with a single-stranded M13mp7-based vector that carries a single example of this lesion at one or other of two unique and adjacent sites. Random samples of progeny phage were sequenced to determine the nature of the replication events that occurred at and around these locations.

[Revision of criteria for locating the accessory pathway by electrocardiogram in Wolff-Parkinson-White syndrome. A new algorithm].

A new algorithm has been developed for locating the anomalous conduction pathway from the ECG which is based on 62 cases of Wolff-Parkinson-White syndrome with a single anomalous conduction pathway, located by epicardial mapping, i.e. 28 on the free edge of the left ventricle (FL), 22 posterior septal, including 11 left (LPS) and 11 right (RPS), 8 right lateral (RL) and 4 right anterior septal (RAS).

SOS-dependent replication past a single trans-syn T-T cyclobutane dimer gives a different mutation spectrum and increased error rate compared with replication past this lesion in uninduced cells.

We have transfected SOS-induced and uninduced cells of a uvrA6 strain of Escherichia coli with single-stranded M13mp7-based vectors that carried a single trans-syn T-T cyclobutane dimer at a unique site. Unlike constructs carrying the cis-syn isomer of this lesion, these vectors could be replicated with modest efficiency (14%) in the absence of SOS induction and therefore provided an opportunity to measure directly the influence of such induction on error rate and mutation spectrum. We found that translesion synthesis in the absence of SOS induction was remarkably accurate; only 4% of the replicated bacteriophage contained mutations, which were exclusively targeted single T deletions.

Epstein-Barr virus polymorphic B-cell lymphoma associated with leukemia and with congenital immunodeficiencies.

Polymorphic B-cell lymphoma seen in four patients with congenital immunodeficiencies and in two patients with leukemia receiving chemotherapy was associated with the Epstein-Barr virus (EBV). The tumors had characteristic histologic features: they were polymorphic consisting of a mixture of lymphoblasts and differentiated cells including plasma cells, and areas of hemorrhagic necrosis were prominent. The tumors were either polyclonal, monoclonal, or multiclonal.

5-azacytidine and 5-azadeoxycytidine inhibit human immunodeficiency virus type 1 replication in vitro.

Chemotherapeutic agents which affect the integration, stability, or inducibility of the human immunodeficiency virus (HIV) provirus would have considerable value in treating acquired immunodeficiency syndrome. Two nucleoside analogs of cytosine, 5-azacytidine and 5-azadeoxycytidine, which seem to have such value because of their capabilities to affect both the stability and the methylation patterns of the nucleic acids into which they are incorporated, were tested for their ability to inhibit the replication of HIV type 1 (HIV-1) in human CEM T cells in vitro. 5-Azadeoxycytidine (1 microM) completely inhibited HIV replication in CEM cells, by the criteria of reduced viral antigen expression and decreased supernatant reverse transcriptase activity, with little toxicity for the treated cells.

Mutational analysis of the lac regulatory region: second-site changes that activate mutant promoters.

Second-site mutations that restored activity to severe lacP1 down-promoter mutants were isolated. This was accomplished by using a bacteriophage f1 vector containing a fusion of the mutant E. coli lac promoters with the structural gene for chloramphenicol acetyltransferase (CAT), so that a system was provided for selecting phage revertants (or pseudorevertants) that conferred resistance of phage-infected cells to chloramphenicol.

High-performance liquid chromatographic determination of mitoxantrone in plasma utilizing non-bonded silica gel for solid-phase isolation to reduce adsorptive losses on glass during sample preparation.

Mitoxantrone, a highly active antineoplastic agent, was found to bind strongly to non-bonded silica gel and glassware. When a Hamilton syringe was used to load and inject a mitoxantrone solution (0.4 microgram/ml in water) on to a high-performance liquid chromatographic (HPLC) system, about 95% of the loaded compound was found to bind to the glass surface of the syringe barrel and could not be removed by rinsing with water.

[Invisible orthodontics: lingual orthodontics].

After an historical, a description of the appliance and the problems met in lingual orthodontics, the authors show that it has come to maturity. Indirect bonding is one of the main elements contributing to success. A large iconography illustrates the different stages of the laboratory and presents an overview of the clinical possibilities of lingual orthodontics.

Inositol and choline levels in the diet and neutral lipid hepatic content of lactating rat.

During lactation a methionine supplemented low protein diet or a sufficient protein diet containing 40% of fructose induced an important hepatic lipidosis. Inositol supplementation, but not choline supplementation, strongly reduced, in the case of a low protein diet, and suppressed, in the case of a sufficient protein diet, this lipidosis.

Milk could decrease the bioavailability of 6-mercaptopurine.

The bioavailability of 6-mercaptopurine (6-MP) administered orally for maintenance therapy of children with acute lymphoblastic leukemia is highly variable. Xanthine oxidase (XO) can transform 6-MP into 6-thioxanthine (6-TX) and 6-thiouric acid (6-TUA), which have no therapeutic value. XO is found in high concentration in cow's milk.

Effects of protein level, methionine supplementation and carbohydrate type of the diet on liver lipid and plasma free threonine contents in the lactating rat.

Eight groups of 13-15 female rats were fed purified diets after littering. Four groups received a low protein (8% casein) diet (groups 8) and the others, a normal protein (20% casein) diet (groups 20). Carbohydrates were supplied either as starch (groups S) or as starch plus 40% fructose (groups F).

Frequency and spectrum of mutations produced by a single cis-syn thymine-thymine cyclobutane dimer in a single-stranded vector.

We have constructed a single-stranded vector that contains a uniquely located cis-syn T-T cyclobutane dimer by ligating a synthetic oligomer containing this UV photoproduct into M13mp7 viral DNA linearized with EcoRI. In the absence of SOS induction, transfection of a uvrA6 mutant of Escherichia coli with this vector gave very few progeny plaques, and the data imply that a single dimer blocks replication in at least 99.5% of the molecules.

UmuC function is not essential for the production of all targeted lacI mutations induced by ultraviolet light.

Up to a quarter or more of the normal yield of lacI- mutations could be induced by ultraviolet light in a uvrA6 umuC122:: Tn5 strain if they were detected by plating on 5-bromo-4-chloro-3-indolyl-beta-D-galactoside medium, where all surviving cells can form colonies. Using phenyl beta-D-galactoside selection, which curtails post-irradiation growth, only low yields of mutations were induced. Nucleotide sequence analysis of 134 spontaneous and 145 ultraviolet light-induced mutations shows that broadly similar kinds of mutations were induced in the umuC mutant and its uvrA6 umuC+ counterpart.

Ultraviolet light induces different spectra of lacI sequence changes in vegetative and conjugating cells of Escherichia coli.

We have analyzed the nucleotide sequence changes responsible for mutations from lacIs to lacI- induced in ultraviolet light-irradiated, excision-deficient cells. Irradiated cells were either used as donors in the conjugational transfer of an F' lacIs plasmid to SOS-induced, excision-deficient recipients or allowed to continue vegetative growth. Although the types and proportions of premutagenic lesions are likely to have been very similar in these two circumstances, analysis of the sequence data shows that different spectra of mutations were induced.

Technetium-99m red blood cell venography in patients with clinically suspected deep vein thrombosis: a prospective study.

We have compared technetium-99m (99mTc) red blood cell (RBC) venography to serial impedance plethysmography (IPG) in 110 consecutive patients with a first episode of clinically suspected deep vein thrombosis (DVT). IPG was performed at Day 0 and, if abnormal, contrast venography was also performed to rule out a falsely positive result. Patients with an initially normal IPG had the test repeated at Days 1, 3, 5 to 7, and 10 to 14.

Liver-function studies in heart-transplant recipients treated with cyclosporin A.

Cyclosporine (CsA) hepatotoxicity has been reported but has not been studied systematically. This study includes 17 patients undergoing heart transplantation (HTx) and being treated with CsA, azathioprine, and corticosteroids. We assessed liver function in these patients before HTx and during the following month by five biological tests: total bile acids (BA), alkaline phosphatase (AP), gamma-glutamyltransferase (GGT), and total bilirubin in serum, and the aminopyrine breath test (ABT).

Oxidative damage in DNA. Lack of mutagenicity by thymine glycol lesions.

Thymine glycol (5,6-dihydroxy-5,6-dihydrothymine) is a base damage common to oxidative mutagens and the major stable radiolysis product of thymine in DNA. We assessed the mutagenic potential of thymine glycols in single-stranded bacteriophage DNA during transfection of Escherichia coli wild-type and umuC strains. cis-Thymine glycols were induced in DNA by reaction with the chemical oxidant, osmium tetroxide (OsO4); modification of thymines was quantitated by using anti-thymine glycol antibody.

[Hepatic microsomal delta 6 and delta 5 desaturations of linoleic acid in lactating rats fed with a low-protein diet supplemented or not with methionine].

In the lactating rat, a low protein diet (8% casein) decreases strongly liver microsomal delta 6 and delta 5 desaturase activities. The supplementation of the diet with 0.4% methionine improves partly delta 6 desaturase activity but has no effect on delta 5 desaturase activity.

The relationship between the nasal cycle and axillary sweat production.

Mean inspiratory nasal resistances and mean axillary sweating rates were recorded bilaterally every 30 minutes for a 5-7 hour period in seven subjects. One subject performed the experiment twice. Nasal resistance was measured using either anterior (n = 5) or posterior (n = 2) rhinomanometry and sweating rate was determined using a filter paper technique.

Physiological modulation of eustachian tube function.

The effect of changing body position on the Eustachian tube opening time (TOT) and nasal conductance (NC) was investigated in 5 subjects. Eustachian tube function was evaluated using a sonotubometric technique and NC was determined by anterior or posterior rhinomanometry. The results showed that both the TOT and NC were decreased by changing the body position from erect to recumbent.

Choanal atresia and associated anomalies.

The authors have studied 130 cases of choanal malformation. They found 53 bilateral atresias, 51 unilateral atresias and 26 cases of choanal stenosis. Fifty-seven of these cases were associated with other anomalies and 38 had at least two features of the CHARGE association (C, colobomas; H, heart defects; A, atresia choanae; R, retarded growth; G, genito-urinary defects; E, ear defects).