ABSTRACT
SETTING: City of Stockholm, Sweden. BACKGROUND: The incidence of tuberculosis (TB) in Sweden increased by 40% between 2003 and 2005. The spread of a unique TB strain resistant to isoniazid (INH) contributed to this increase. OBJECTIVE: To describe outbreaks of TB caused by this single strain, elucidate possible causes for its extensive spread and identify shortcomings of the TB control programme in Sweden. RESULTS: We identified a cluster consisting of 102 culture-confirmed TB cases with identical DNA fingerprints and 26 epidemiologically related cases, not confirmed by culture, all diagnosed between 1996 and 2005. Five partly separate outbreaks of this strain were discovered. Epidemiological links were established for 56% of the culture-confirmed cases and for all cases not confirmed by culture. Three patients died while receiving treatment, four became failures and eight defaulted or were lost to follow-up. Only eight patients received directly observed treatment (DOT) up to a period of 3 months, although 40% had poor adherence. CONCLUSIONS: Shortcomings of the national TB programme were revealed. Improved contact tracing and case holding, including DOT, is crucial to reduce TB transmission in Sweden.
Subject(s)
Antitubercular Agents/pharmacology , Disease Outbreaks , Isoniazid/pharmacology , Mycobacterium tuberculosis/drug effects , Tuberculosis, Pulmonary/epidemiology , Adolescent , Adult , Antitubercular Agents/therapeutic use , Child , Child, Preschool , Cluster Analysis , Contact Tracing , DNA Fingerprinting , Directly Observed Therapy , Disease Outbreaks/prevention & control , Female , Humans , Infant , Isoniazid/therapeutic use , Male , Middle Aged , Mycobacterium tuberculosis/genetics , Sweden/epidemiology , Tuberculosis, Pulmonary/drug therapy , Tuberculosis, Pulmonary/prevention & control , Tuberculosis, Pulmonary/transmissionABSTRACT
The contact time of a vehicle on the cornea is of utmost importance for ocular drug delivery. In the present study rheological measurements were performed to study the gel and the sol-gel transition of an in situ gel, Poloxamer 407. The rheological measurements and a small in vivo study of ocular residence times in humans were used to evaluate poloxamer as an ocular vehicle. An increasing concentration of poloxamer resulted in a slightly increasing elasticity of the gels and a decreasing sol-gel transition temperature. The contact time increased with increasing concentration of poloxamer which could be explained and correlated with the rheology of poloxamer solutions/gels mixed with simulated tear fluid. The maximum contact time for the preparations studied was about 1 h. The poloxamer system did not seem to be promising as an ophthalmic in situ gel due to the strong concentration dependence of the sol-gel transition temperature combined with the dilution that occurs in the eye.
Subject(s)
Gels/chemistry , Ophthalmic Solutions/chemistry , Poloxamer/chemistry , RheologyABSTRACT
One of the reasons for the relatively low bioavailability of conventional eye drops is their short precorneal contact times. In situ gels are promising ocular drug delivery systems since they are conveniently dropped into the eye as a liquid whereafter they undergo a transition into a gel. Due to their elastic properties hydrogels resist ocular drainage leading to longer contact times. In this paper the rheology of Gelrite in situ gels was studied. A complementary in vivo study for determining precorneal contact times in humans and in rabbits was performed. The elastic moduli of the gels increased with increasing concentration of electrolytes. At physiological concentration of the electrolytes, the elasticity of the gels was independent of Gelrite concentration. The human contact times increased up to 20 h with decreasing osmolality of the formulations. The results indicate that a high rate of the sol/gel transition results in long contact times.
Subject(s)
Eye/metabolism , Ophthalmic Solutions/metabolism , Polysaccharides, Bacterial/metabolism , Animals , Eye/drug effects , Humans , Ophthalmic Solutions/chemistry , Ophthalmic Solutions/toxicity , Polysaccharides, Bacterial/chemistry , Polysaccharides, Bacterial/toxicity , Rabbits , RheologyABSTRACT
A quantitative study was made of the enterochromaffin (EC) cells, visualized with the Masson (slightly modified) and Falck-Hillarp techniques, in the rat gastrointestinal tract. Different factors influencing the quantification were analysed and the magnitude of methodological errors was estimated. The two histochemical techniques visualized the EC cells in different ways, influencing the quantification results. This means that a comparison of the quantitative results obtained by these techniques can only be made after correction by some factors. The frequency of EC cells is given as the number of cells both per mm3 mucosa (cellular density) and per segment of mucosa with a base of 1 mm2. The latter information takes into account both cellular density and mucosal thickness. The highest frequency of EC cells was found in the pyloric gland area of the stomach. On the border with the duodenum there was a marked decrease in this frequency and in the whole intestine the frequency was low, with only minor fluctuations of the mean values. The frequency was increased in the caecum, followed by a gradual decrease in the large intestine. The quantitative variation of the EC cells at the same gastrointestinal level was considerable, and was greater between animals than between serial sections within the same animal. The difference in EC cell frequency that was required to give significance was calculated. For quantitative studies the Masson method has some minor advantages over the Falck-Hillarp technique, as routine formalin-fixed deparaffinized sections can be used and no counterstaining is needed for the areal estimation.
