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At least 955 records · Page 53Linked to original sources
PubMed1984

Evaluation of a rapid radiometric differentiation test for the Mycobacterium tuberculosis complex by selective inhibition with p-nitro-alpha-acetylamino-beta-hydroxypropiophenone.

This study is an evaluation of a rapid technique for the differentiation of the Mycobacterium tuberculosis complex from other mycobacteria, using p-nitro-alpha-acetylamino-beta- hydroxypropiophenone (NAP) as a selective inhibitory agent. A total of 416 coded cultures, 234 cultures belonging to the M. tuberculosis complex and 182 cultures belonging to 35 other mycobacterial species, were tested in two laboratories for p-nitro-alpha-acetylamino-beta- hydroxypropiophenone inhibition to concentrations of 5 and 10 micrograms of NAP per ml in Middlebrook 7H12 liquid medium. Two testing modes were compared: the indirect, in which a large bacterial inoculum was used from an isolated culture on a solid medium, and the direct, which used a small inoculum from 7H12 medium. A decrease or no increase in daily 14CO2 output as measured by a BACTEC system was considered evidence of inhibition. The data presented show that a concentration of 5 micrograms of NAP per ml can effectively separate the M. tuberculosis complex from other mycobacterial species in 4 to 6 days. The direct test data show that, unlike other conventional biochemical tests, it does not require a heavy inoculum of mycobacteria and can therefore be performed soon after growth is detected by the radiometric method.

Bacteriological Techniques↗
PubMed1984

Fatal ventricular tachycardia in association with propafenone, a new class IC antiarrhythmic agent.

A man with a past history of malignant ventricular arrhythmias occurring late after myocardial infarction was admitted for assessment. Monitoring revealed frequent ventricular premature beats and occasional non-sustained runs of ventricular tachycardia. Other drugs having failed, he was started on oral propafenone which is a new Vaughan Williams class IC antiarrhythmic agent. Several hours after starting this drug he had incessant ventricular tachycardia and subsequently died. Other class IC agents have been shown to have a high incidence of proarrhythmic effects, and particular care should be taken with these potent new drugs.

Anti-Arrhythmia Agents↗
PubMed1975

Mechanism of methylxanthine sensitization of norepinephrine responses in a coronaryartery.

Beta-adrenergic receptor-mediated relazation to norepinephrine was enhanced by caffeine amd aminophylline in a coronary artery preparation of the beef in vitro. Augmented responses were not obtainable in the presence of known inhibitors of the extraneuronal uptake and metabolism of norepinephrine, estradiol-17beta, and the haloalkylamine GD-131, which themselves potentiate responses. In addition, the effect on the norepinephrine dose-response curve of the combination of a methyixanthine and U-0521,the latter a potent inhibitor of catechol O-methyltransferase, the major enzyme of catecholamine inactivation in vascular tissue, did not differ from that of U-0521 alone. Studies of the extraneuronal accumulation of '3H-labeled norepinephrine revealed that caffeine and aminophylline, along with the known inhibitors, materially reduced theaccumulation of label in coronary tissue. It is concluded that the methylxanthinesenhance beta-adrenergic receptor-mediated responses via a blockade of catecholamine uptake, giving rise to an increased concentration of agonist at receptors, and not by an action linked to cyclic AMP accumulation, consequent to receptor activation.

Aminophylline↗
PubMedDate not supplied

Skin penetration and sun protection factor of five UV filters: effect of the vehicle.

To gain information about efficacy and safety of sunscreens, we compared the skin penetration of ultraviolet (UV) filters from two vehicles, i.e. an oil-in-water (O/W) emulsion gel and petrolatum jelly both in vitro and in vivo, as well as the corresponding pharmacological effect, i.e. the sun protection factor (SPF) in vivo. The UV filters studied were benzophenone-3 (BPH), ethylhexyl methoxycinnamate (EHM), butyl methoxydibenzoyl methane, ethylhexyl salicylate and homosalate. The human skin penetration of these five chemicals from the two vehicles was determined both in vitro using Franz cells and in vivo using a standardized tape-stripping method. The SPF of the two sunscreens was determined in vivo following the COLIPA guidelines. In vitro none of the filters permeated through the skin after 6 h of product application and very little could be found in the skin. BPH and EHM were the only UV filters found in the dermis (both after 30 min and 6 h). An effect of the vehicle could be noticed only for BPH after 30 min in the dermis and 6 h in both dermis and epidermis. In vivo, no differences in the amount of individual UV filters (in % of the applied dose) in the 15 first strips of the stratum corneum (SC) were found following 30 min of application of the formulations; however, the amount of UV filters that were retained in the SC was significantly higher (around 3 times) with the O/W emulsion gel than with the petrolatum jelly. This difference between the two vehicles was also of consequence for the SPF in vivo measured 30 min after application of the products (SPF congruent with 18 with the O/W emulsion gel compared to SPF congruent with 10 with the petrolatum jelly). By choosing the right vehicle or optimizing it, not only sunscreen products can be significantly improved in terms of pharmacological efficacy but the potential toxicological risk associated with the skin penetration of UV filters may be significantly reduced.

Adult↗
PubMedDate not supplied

Lateral spreading of topically applied UV filter substances investigated by tape stripping.

The lateral spreading of topically applied substances is a competitive process to the penetration into the stratum corneum (SC). The penetration of topically applied UV filter substances into the human SC and the lateral spreading were investigated in vivo. Tape stripping in combination with spectroscopic measurements was used to study both processes of two UV filter substances. The concentration of both UV filters was determined inside and outside the application area by varying the application and tape stripping protocol. A spreading of the topically applied substances from the treated to the untreated areas was observed, which caused a concentration gradient. This lateral spreading depends on the time between application and tape stripping and the size of the treated skin area. Significant amounts of topically applied substances were found adjoining the application area, due to the lateral spreading which takes place on the skin surface. In general, the lateral spreading must be considered to be a competitive process when studying penetration processes of topically applied substances. It has to be considered during drug treatment of small limited skin areas and for the interpretation of recovery rates obtained in penetration studies.

Administration, Cutaneous↗