Inhibition of the multiple antibiotic resistance (mar) operon in Escherichia coli by antisense DNA analogs.

The multiple antibiotic resistance operon (marORAB) in Escherichia coli controls intrinsic susceptibility and resistance to multiple, structurally different antibiotics and other noxious agents. A plasmid construct with marA cloned in the antisense direction reduced LacZ expression from a constitutively expressed marA::lacZ translational fusion and inhibited the induced expression of LacZ in cells bearing the wild-type repressed fusion. The marA antisense construction also decreased the multiple antibiotic resistance of a Mar mutant. Two antisense phosphorothioate oligonucleotides, one targeted to marO and the other targeted to marA of the mar operon, introduced by heat shock or electroporation reduced LacZ expression in the strain having the marA::lacZ fusion. One antisense oligonucleotide, tested against a Mar mutant of E. coli ML308-225, increased the bactericidal activity of norfloxacin. These studies demonstrate the efficacy of exogenously delivered antisense oligonucleotides targeted to the marRAB operon in inhibiting expression of this chromosomal regulatory locus.

Mechanism of mutation on DNA templates containing synthetic abasic sites: study with a double strand vector.

Mutagenesis at abasic sites was investigated in E.coli and simian kidney (COS) cells using a duplex shuttle vector containing synthetic analogs of deoxyribose on the phosphodiester backbone. Lesions were positioned on opposite strands of the vector. When the tetrahydrofuranyl analog was used as the abasic site, AT or TA pairs (65-80%) were introduced at the site of the bistrand lesion. Mutagenesis occurred in the absence of SOS induction. Single base deletions (> 80%) dominated the mutational spectra for propanyl and ethanyl analogs of abasic sites lacking a ring structure. For all abasic site analogs, a small proportion of G/C and C/G pairs (6-10%) were observed. dAMP was incorporated predominantly opposite tetrahydrofuranyl sites positioned in the single strand region of a gapped duplex vector. We conclude from these studies that abasic sites positioned in a bistrand configuration are highly mutagenic in E.coli and COS cells. Repair DNA synthesis may be involved in this process.

Cytogenetic effects of singlet oxygen.

Singlet oxygen was generated in the gas phase at atmospheric pressure by the method of heterogeneous photosensitization. In vitro exposure of human lung WI-38 fibroblasts to gas-phase singlet oxygen resulted in sister chromatid exchange.

Oxidation of phosphatidylcholine membranes by singlet oxygen generated in the gas phase.

Singlet-oxygen (1O2) was generated in the gas phase by heterogeneous photosensitization and bubbled into suspensions of phosphatidylcholine (PC) liposomes. Lipid peroxidation and membrane lysis were observed, and were dependent on the 1O2 concentration and the degree of unsaturation of the liposome. An analysis based on large target diffusion theory indicates that approximately 5000, 2800, and 1600 interactions were required for the lysis of large dioleoylPC, dilinoleoylPC and dilinolenoylPC liposomes, respectively.

Tears of the retinal pigment epithelium: occurrence in association with choroidal effusion.

Two patients developed large tears of the retinal pigment epithelium associated with choroidal effusion. One tear occurred after combined cataract/filtration surgery complicated by postoperative choroidal detachment; the second developed in a patient with idiopathic uveal effusion syndrome. Weakness of the junctions of the pigment epithelial cells secondary to the accumulation of fluid in the subretinal or suprachoroidal space may result in tearing of the retinal pigment epithelium as it is stretched.

Cytotoxic effects of singlet oxygen.

The toxic effects of gas-phase singlet oxygen, 1O2, on the ciliated respiratory epithelium of hamster trachea have been demonstrated. Tracheal explants treated with 1O2 showed a dose-dependent decrease in cilia beating frequency and focal ciliostasis. A statistically significant decrease in ciliary activity occurred at 1O2 concentrations as low as 154 ppb after a 2-hr exposure. Cytological alterations in the mucociliary epithelium were observed in explants exposed to 235 ppb 1O2 or greater. When cytotoxic effects were related to the time of exposure to 1O2, maximum effects occurred after a 4-hr exposure. In vitro recovery studies indicate that ciliary activity returned to normal between 4 and 8 hr after exposure.

Evaluation of host resistance and immunity in mice exposed to the carbamate pesticide aldicarb.

Adult female Swiss-Webster and B6C3F1 mice received distilled water only or water containing 0.1, 1.0, 10, 100, or 1000 ppb of aldicarb daily for 34 days. The target concentration of aldicarb present in the 10 ppb dosing solution was analytically verified on a daily basis as was its stability over a 48-hr period. To develop an immune profile of this compound, functional parameters measured after exposure included resistance to infectious viral challenge; quantitation of splenic antibody-forming cells to sheep erythrocytes and circulating serum antibody levels; splenic lymphocyte blastogenesis to T- and B-cell mitogens; and mixed-lymphocyte culture response. To supplement the functional assays, complete blood counts, differential leukocyte counts, and body and relative organ weights were measured. In addition, gross and histopathologic examinations of tissues relevant to the immune system were performed. The absence of significant effects on any of these parameters suggests that aldicarb at environmentally relevant exposure concentrations is not immunotoxic in rodents.

Severe pulmonary arterial stenoses in Conradi-Hünermann disease.

A 5-month-old male infant with chondrodystrophia punctata type Conradi-Hünermann showed electrocardiographically an increasing right ventricular hypertrophy. Echocardiographically an enormous enlarged right ventricle with signs of supra-systemic pressure was found. No other intracardiac defects could be seen. Angiography showed severe peripheral pulmonary arterial stenoses of both main arteries. Balloon-dilatation or surgical intervention was supposed to have no beneficial effect. At the age of 6 months the patient died.

Evidence of DNA repair in organ cultures of hamster tracheal epithelium following exposure to gas phase singlet oxygen.

Autoradiographic identification of unscheduled DNA synthesis (UDS) in short-term organ culture of hamster tracheal epithelium has been used as a predictive test for mutagenic and/or carcinogenic compounds. Tracheal explants were treated for 2 h with singlet delta oxygen plus [3H]thymidine. Silver grains over the nuclei of epithelial cells from the superficial layer of the mucosa were observed, indicating UDS. Control cultures, exposed to the gas phase without singlet oxygen, failed to elicit UDS.

Production of singlet delta oxygen by atmospheric pollutants.

Singlet delta oxygen (1O2) was generated at atmospheric pressure using heterogeneous gas-phase photosensitization. Polycyclic aromatic hydrocarbons (PAH), known constituents of the atmosphere, were found to be efficient sensitizers in the production of singlet delta oxygen under simulated environmental conditions. A novel mechanism involving singlet delta oxygen is proposed in which PAH on particle surfaces are self-activated to form direct-acting mutagens.

Biological effects of singlet delta oxygen on respiratory tract epithelium.

Exposure of hamster tracheal organ cultures to gas phase singlet delta oxygen, O2, at atmospheric pressure produced significant alterations in the mucociliary epithelium resulting in changes in ciliary activity and cellular morphology.

[Congenital tuberculosis (author's transl)]. / Konnatale Tuberkulose.

A prematurely born infant (35 weeks of gestational age) developed signs of respiratory insufficiency, and fever, beginning at the 17th day of life; x-ray examinations showed small and large spotted lung infiltrations which grew and confluated rapidly in spite of broad antibiotic treatment. At the 29th day intubation and artificial ventilation became necessary; cultures of tracheal fluid remained sterile, Ziehl-Neelsen stains were not done. The infant died at the age of 35 days. Only at autopsy the diagnosis " congenital tuberculosis" could be made; examinations of the mother who was thought to be healthy, revealed a severe epitheloid cell tuberculosis of the endometrium. -- Mode of transmission, pathology, clinical symptoms, prophylaxis, and therapy of congenital tuberculosis are being reviewed.

[A contribution to the medical and organizational care of high-risk premature infants and newborn (author's transl)]. / Zur medizinischen und organisatorischen Betreuung gefährdeter Früh- und Neugeborener.

Perinatal mortality is a qualitative parameter for the obstetric and neonatologic efficiency of an obstetric center. The present study conducted at the Herford clinical center, based on 3,700 case histories from 1972 to 1976, revealed a drop of the uncorrected perinatal mortality from 35.08% to 14.23%, and a drop of the corrected perinatal mortality from 21.35% to 5.02%. Two groups with an observation period of 2.5 years each, were compared with each other to demonstrate the efficiency of modern perinatologic care and control methods. The methods of intensive care and control of high-risk pregnancy and high-risk parturition (ultrasound, cardiotocography, fetal blood analysis; tocolysis, laboratory diagnostics of placental insufficiency), practised since 1974, and the close cooperation with a newborn intensive-care ward of the infant hospital of the Herford center have brought about a definite improvement in perinatologic efficiency.

Limited collaborative study of an optional method for the isolation of light filth from fig and fruit paste.

The present official first action method for the isolation of light filth from fig and fruit paste, 44.083(a), occasionally yields excessive plant debris on filter papers, which causes difficulty in effectively counting insect filth. The proposed method provides the option of an additional flotation of trapped off material in a Corning percolator. This revision has been adopted as official first action as an alternative to 44.083(a).

Inorganic particle content of foods and drugs.

Inorganic particulate matter in foods and drugs is discussed from the standpoint of determination by optical microscopy, source, and regulatory significance. Some particulate matter may be generated as extraneous material and traced to specific operational practices during processing and production with excessive levels associated with deficiencies in good manufacturing practices. Other particles, such as talc and asbestos, may be incorporated as additives during their use in production. Data on particles in parenteral drugs are discussed generally. Specific data on glass particles in foods and sand and soil particles in spices are presented.