Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tars”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1990

Wood tars allergy, cross-sensitization and coal tar.

In a population of 1883 patients tested for allergic contact dermatitis (1985-1988), a prevalence of 5.4% (103 cases) was seen for wood tars (ICDRG allergen, 12% pet.) sensitization. In this group (n = 103), retrospectively, a combined allergy was seen to wood tars and fragrance mix in 43% and to wood tars and balsam of Peru in 31%. A combined allergy to wood tars and coal tar was seen in 19 patients (18.5%): 14 to liquor carbonis detergens (LCD), 8 to lianthral and 3 to both LCD and lianthral. Within the group with wood tars allergy (n = 103), a minority (n = 37) had a history of atopic dermatitis. Comparison of the test results in atopic and non-atopic subgroups (within the group of 103) revealed a higher incidence of combined wood tars-fragrance mix allergy in the atopic group (n = 37). In this group, a lower incidence of combined wood tars-coal tar sensitization was seen in comparison with the non-atopic group (n = 66). The authors believe that combined "wood tars-coal tar" allergy could be the consequence of cross-sensitization rather than due to long-term previous topical treatment with tar derivatives. The high % of cross-allergy between wood tars and fragrance mix emphasizes the role of wood tars as an important indicator allergen in perfume allergy.

Coal Tar↗
PubMed1992

Respiratory effects of lowering tar and nicotine levels of cigarettes smoked by young male middle tar smokers. II. Results of a randomised controlled trial.

STUDY OBJECTIVE: The aim was to investigate the effect on respiratory health of male middle tar smokers changing the tar and nicotine levels of the cigarettes they smoke for a six month period. DESIGN: This was a randomised controlled trial. Middle tar smokers were randomly allocated to smoke one of three different types of cigarette (low tar, middle nicotine; middle tar, middle nicotine; and low tar, low nicotine) in place of their usual cigarette for a six month period. Main outcome measures were assessment of respiratory health by documenting respiratory symptoms and peak expiratory flow rates, and of nicotine inhalation by measuring the urinary excretion of nicotine metabolites. SETTING: 21 local authority districts of England. SUBJECTS: Participants were male middle tar smokers aged 18-44 years. MAIN RESULTS: Changes in the measures of respiratory health showed little difference over the trial period between the three cigarette groups. Analyses of the urinary nicotine metabolites showed that smokers allocated to each of the three study cigarettes adjusted their smoking so that throughout the trial their nicotine inhalation differed little from their pretrial intakes when they were smoking their own cigarettes. As a result of the altered patterns of smoking to compensate for the reduced nicotine yields of the three study cigarettes, the tar intake of those allocated to smoke the middle tar, middle nicotine cigarettes remained essentially unchanged, while those allocated to smoke the low tar, low nicotine and low tar, middle nicotine cigarettes had calculated reductions in tar intakes of about 14% and 18%, respectively. CONCLUSIONS: Due to the phenomenon of compensation, tar intake can only be reduced substantially by using a cigarette with a markedly lower tar/nicotine ratio. Nevertheless reductions of up to about 18% in tar intake failed to result in any detectable effect on respiratory symptoms or peak expiratory flow rates over a six month period.

Adolescent↗
PubMed1992

Respiratory effects of lowering tar and nicotine levels of cigarettes smoked by young male middle tar smokers. I. Design of a randomised controlled trial.

STUDY OBJECTIVE: The aim was to investigate the effect on respiratory health of male middle tar smokers changing the tar and nicotine levels of the cigarettes they smoke for a six month period. DESIGN: This was a randomised controlled trial. Middle tar smokers were randomly allocated to smoke one of three different types of cigarette (low tar, middle nicotine; middle tar, middle nicotine; and low tar, low nicotine) in place of their usual cigarette for a six month period. Main outcome measures were assessment of respiratory health by documenting respiratory symptoms and peak expiratory flow rates, and of nicotine inhalation by measuring the urinary excretion of nicotine metabolites. SETTING: 21 local authority districts of England. SUBJECTS: Participants were male middle tar smokers aged 18-44 years. MAIN RESULTS: Postal questionnaires were sent to 265,016 individuals selected from the electoral registers of 21 local authority districts of England; 64% of questionnaires were returned revealing 7736 men aged 18-44 years who smoked only middle tar cigarettes. Of these, 7029 (90%) were sent a health warning and 707 (10%) were not; the latter acted as a control group to assess the effect of the health warning. Of the 7029 men who had received a health warning and were visited at the recruitment stage, 2666 agreed and were eligible to participate in the trial although only 1541 (58% of those who agreed and were eligible) actually started smoking the study cigarettes; 643 men (24% of those willing to participate at the beginning of the trial and 42% of those who actually started smoking the study cigarettes) completed the trial smoking the study cigarettes. Of these, 213 were in the low tar middle nicotine group, 220 were in the middle tar middle nicotine group, and 210 were in the low tar low nicotine group. CONCLUSIONS: This study shows the feasibility of identifying and recruiting sufficient numbers of male middle tar smokers, with adequate numbers completing the trial, to detect any changes in respiratory health over a six month period.

Adolescent↗
PubMed1986

Reduction of tar, nicotine and carbon monoxide intake in low tar smokers.

Blood nicotine, cotinine, and carboxyhaemoglobin (COHb) concentrations were measured in 392 smokers (255 women and 137 men) of "middle tar" (17-22 mg), "low to middle" (11-16 mg), and "low tar" (less than 11 mg) cigarettes. Since tar intake cannot yet be measured directly, we devised an index to estimate it based on the use of measured levels of an intake marker (eg, blood nicotine) and the ratio of the tar to marker yields of the cigarettes. This approach was validated by its ability to enhance the prediction of levels of one marker by use of another. In a practical test, using COHb and the CO/nicotine yield ratio of the cigarettes, the mean blood nicotine concentration of the low tar smokers was predicted to be 31.9 ng/ml compared with the measured mean of 31.8 ng/ml. Our main findings were that despite substantial compensatory increases in inhalation, the low tar smokers took in about 25% less tar, about 15% less nicotine, and about 10% less carbon monoxide than smokers of middle and low to middle tar cigarettes. These results indicate that low tar cigarettes of the type available in Britain since the late 1970s are likely to prove less harmful than other brands. Monitoring of smoke intakes could supplement epidemiological approaches and provide earlier evidence of whether changing cigarette designs lead to any significant dosage reduction that could affect the risk of disease.

Carbon Monoxide↗
PubMed1990

Formation of DNA adducts in the skin of psoriasis patients, in human skin in organ culture, and in mouse skin and lung following topical application of coal-tar and juniper tar.

Preparations of coal-tar and juniper tar (cade oil) that are used in the treatment of psoriasis are known to contain numerous potentially carcinogenic polycyclic aromatic hydrocarbons (PAH). Evidence of covalent binding to DNA by components of these mixtures was sought in a) human skin biopsy samples from 12 psoriasis patients receiving therapy with these agents, b) human skin explants maintained in organ culture and treated topically with the tars, and c) the skin and lungs of mice treated with repeated doses of the formulations following the regimen used in the clinic. DNA was isolated from the human and mouse tissues and digested enzymically to mononucleotides. 32P-Post-labeling analysis revealed the presence of aromatic DNA adducts in the biopsy samples at levels of up to 0.4 fmol total adducts/microgram DNA. Treatment of human skin in organ culture produced similar levels of adducts, while treatment with dithranol, a non-mutagenic therapeutic agent, resulted in chromatograms indistinguishable from those from untreated controls. In mouse skin, coal-tar ointment and juniper tar gave similar DNA adduct levels, with a similar time-course of removal: maximum levels (0.5 fmol/microgram DNA) at 24 h after the final treatment declined rapidly to 0.05 fmol/microgram at 7 d, thereafter declining slowly over the succeeding 25 d. However, while coal-tar ointment produced only very low levels of adducts in mouse lung (less than 0.03 fmol/microgram DNA), juniper tar produced adducts at a high level (0.7 fmol/microgram DNA) that were persistent in this tissue. These results provide direct evidence for the formation of potentially carcinogenic DNA damage in human and mouse tissue by components of these therapeutic tar preparations.

Administration, Topical↗
PubMed1986

No difference between urinary mutagenicity in smokers of low-tar and medium-tar cigarettes: a double-blind cross-over study.

Urinary mutagenicity, blood carboxyhemoglobin and serum thiocyanate levels were measured in young, healthy volunteers smoking a fixed number of either low-tar (5 mg/cig.) or medium-tar (15 mg/cig.) cigarettes. The experiment was performed in a double-blind cross-over fashion. The volunteers were under daily control, and their diet and environment were standardized. The urinary mutagenic activity responded dose-dependently to the number of cigarettes smoked (0, 5, 10 or 20 per day), but there was no difference between the smokers of low-tar and medium-tar cigarettes. Neither were any significant differences found in blood carboxyhemoglobin nor serum thiocyanate. These results suggest that there is no substantial difference between the low-tar and medium-tar cigarette as to the inhalation of hazardous compounds in the real smoking situation.

Adult↗
PubMed1985

[Effect of coal tar on cignolin erythema--1 hour treatment of psoriasis with high-dose cignolin with and without tar].

Coal tar applied simultaneously showed a suppressive effect on anthralin erythema. This effect was demonstrated by an epicutaneous test 24 hours (27 patients) and 1 hour (46 patients) after application of various concentrations of anthralin combined with tar 3%. In a clinical study on 9 patients, anthralin 3% alone or combined with tar 10% were administered in a right and left comparison on symmetrical chronic psoriatic lesions for 1 hour daily. Anthralin plus tar exhibited a stronger anti-psoriatic effect than anthralin alone did. Tar reduced the anthralin erythema in the perilesional skin. These findings favor the combination of coal tar and anthralin in the 1-hour treatment schedule of psoriasis.

Adult↗
PubMed1986

[Effect of various kinds of tar and tar concentrations on anthralin erythema].

The effect of tar on anthralin-induced erythema was epicutaneously tested in ten patients. 3%, 5%, or 10% crude coal tar or coal tar solution was added to vaseline containing anthralin. A 5% or 10% tar preparation significantly suppressed the anthralin erythema induced by 0.5 to 1.0% anthralin having been applied for 24 hrs. In these concentrations, coal tar solution was at least as effective as coal tar itself.

Adolescent↗
PubMed1992

Conserved nucleotides in the TAR RNA stem of human immunodeficiency virus type 1 are critical for Tat binding and trans activation: model for TAR RNA tertiary structure.

Interaction between the human immunodeficiency virus type 1 (HIV-1) trans-activator Tat and its cis-acting responsive RNA element TAR is necessary for activation of HIV-1 gene expression. We investigated the hypothesis that the essential uridine residue at position 23 in the bulge of TAR RNA is involved in intramolecular hydrogen bonding to stabilize an unique RNA structure required for recognition by Tat. Nucleotide substitutions in the two base pairs of the TAR stem directly above the essential trinucleotide bulge that maintain base pairing but change sequence prevent complex formation with Tat in vitro. Corresponding mutations tested in a trans-activation assay strongly affect the biological activity of TAR in vivo, suggesting an important role for these nucleotides in the Tat-TAR interaction. On the basis of these data, a model is proposed which implicates uridine 23 in a stable tertiary interaction with the GC pair directly above the bulge. This interaction would cause widening of the major groove of the RNA, thereby exposing its hydrogen-bonding surfaces for possible interaction with Tat. The model also predicts a gap between uridine 23 and the first base pair in the stem above, which would require one or more unpaired nucleotides to close, but does not predict any other role for such nucleotides. In accordance with this prediction, synthetic propyl phosphate linkers of equivalent length to 1 or 2 nucleotides, were found to be fully acceptable substitutes in the bulge above uridine 23, demonstrating that neither the bases nor the ribose moieties at these positions are implicated in the recognition of TAR RNA by Tat.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Binding of Tat protein to TAR region of human immunodeficiency virus type 1 blocks TAR-mediated activation of (2'-5')oligoadenylate synthetase.

The TAR sequence of the 5' leader of HIV-1 long terminal repeat-directed mRNA was found to be able to bind to and to activate double-stranded RNA-dependent (2'-5')A synthetase. Binding of TAR to the purified synthetase in vitro was abolished by addition of HIV-1 Tat protein, which binds to this sequence with a high affinity. Inhibition of TAR-mediated activation of (2'-5')A synthetase by Tat was prevented in the presence of the Zn2+ and Cd2+ chelators o-phenanthroline and penicillamine, which did not impair TAR-synthetase interaction. Transient expression assays of bacterial chloramphenicol acetyltransferase (CAT) gene in HeLa cells revealed that the levels of both CAT mRNA and CAT protein decreased after treatment of the cells with interferon, if CAT gene was linked to HIV-1 TAR segment. Cotransfection of the cells with a tat sequence containing plasmid rendered CAT gene expression insensible to the action of interferon.

2',5'-Oligoadenylate Synthetase↗
PubMed1975

Evaluation of coal tar fractions for use in psoriasiform diseases using the mouse tail test. (I) High and low temperature tars and their constituents.

'High' and 'low' temperature tars were evaluated on parakeratotic mouse tail skin, which was used as a model for the psoriatic keratinization process. The skin was examined histologically for signs of induced granular layers in previously scaly areas; epidermal thicknesses were also measured. It appears that the acidic (phenolic) fractions of coal tars induce granular layers and cause epidermal thickening, whereas neutral constituents alone only cause thickening. It is suggested that tar acids should be further investigated for anti-psoriatic activity.

Animals↗
PubMed1989

Low concentration dithranol and coal tar (Psorin) in psoriasis: a comparison with alcoholic coal tar extract and allantoin (Alphosyl).

Psoriasis is difficult to manage in general practice, mainly because the standard treatments produce side effects, or are ineffective in both the short and long term. In recent years, the main topical therapies have included extracts of coal tar or dithranol. In a six-week within-patient trial, 23 patients applied two different treatments to the left and right halves of their bodies. A new preparation (Psorin, Thames Laboratories), containing relatively low concentrations of dithranol and crude coal tar, was significantly more effective and more acceptable than a refined alcoholic extract of coal tar with allantoin (Alphosyl, Stafford Miller Ltd).

Adolescent↗
PubMedDate not supplied

Low-tar and high-tar cigarettes.

Mice were exposed for 7 to 8 minutes on weekdays to fresh smoke from high-tar (HT) or low-tar (LT) cigarettes for varying periods of up to 36 weeks. Mice exposed to HT cigarettes exhibited more marked alterations in humoral immune responsiveness, hematological profiles, and pulmonary pathologic findings than those exposed to LT cigarettes. However, cell-mediated immune responsiveness to both bacterial and tumor-specific antigens was depressed similarly in animals exposed to HT or LT cigarettes. Furthermore, the growth rates of subcutaneously established tumors were enhanced similarly in the two groups, with respect to those in control animals.

Animals↗
PubMed1985

1-hydroxypyrene in human urine after exposure to coal tar and a coal tar derived product.

A method for isolating 1-hydroxypyrene from urine is described. The presence of 1-hydroxypyrene in urine was identified by fluorescence excitation and emission scanning after HPLC-separation. 1-Hydroxypyrene could be detected in the urine of rats following oral administration of as little as 0.5 microgram pyrene. The dose-dependence of 1-hydroxypyrene in urine was evident after a wide range of pyrene dosing. After therapeutical coal tar treatment of dermatological patients the enhanced excretion of 1-hydroxypyrene was highly significant. Employees of a creosote impregnating plant showed an excretion pattern of 1-hydroxypyrene which could be related to their work. 1-Hydroxypyrene in urine of non-exposed people was very low, but detectable. It is suggested that the method reported is suitable for the assessment of uptake of man to pyrene, a compound that is commonly present in work environments which are associated with pollution of polycyclic aromatic hydrocarbons.

Adult↗
PubMed1988

Airborne concentrations, skin contamination, and urinary metabolite excretion of polycyclic aromatic hydrocarbons among paving workers exposed to coal tar derived road tars.

The exposure of surface dressing workers to polycyclic aromatic hydrocarbons (PAH) was studied. Four different paving sites, at which coal tar-containing binders were applied, were selected as work sites with high exposure levels of PAH. Breathing zone airborne particulates, contamination of the skin with PAH, and 1-hydroxypyrene in urine of the workers involved in chip sealing were determined. Substantial concentrations of cyclohexane-soluble airborne particulate matter were found (GM = 0.2 mg/m3, n = 28). Skin contamination was determined using two different methods: with exposure pads and by hand washing. Pads were mounted on several parts of the body: wrist, elbow, neck, shoulder, and ankle. The pads located on the wrist appeared to be the most contaminated (pyrene: GM = 22 ng/1.77 cm2, n = 40). The end-of-shift hand washing showed that the hands of the workers were contaminated with PAH (pyrene: GM = 70 micrograms, n = 35). Preshift hand washing showed far lower, but detectable, quantities of PAH on workers' hands (pyrene: GM = 5 micrograms, n = 35). Enhanced levels of urinary 1-hydroxypyrene among the workers were found. The highest levels were found in the end-of-shift urine samples. Correlations between the pyrene exposure variables were studied. Significant positive correlations were found between pyrene on the wrist pad versus end-of-shift urinary 1-hydroxypyrene; between pyrene on the hands versus end-of-shift urinary 1-hydroxypyrene; and between the two different skin contamination variables.

Air Pollution↗