RESUMEN
Specific targeting of tissues and/or cells is essential for any type of drug delivery system because this determines the efficacy and side effects of the drug. Poly lactic-co-glycolic acids (PLGA) have long been used as biomaterials for drug delivery due to their excellent biocompatibility and biodegradability. Direct visualization of PLGA particles is feasible even within tissues, and cell specificity of the drug delivery system is normally assessed by using labeled particles. However, particle labeling alone does not address factors such as the release and distribution of the drug. Thus, it is desirable to set up a simulation system of drug release and distribution in vivo. In the present study, we aimed to establish a method to simulate drug distribution in PLGA drug delivery by using Hoechst 33342 as an imitating drug. Our approach enabled us to identify, isolate, and characterize cells exposed to Hoechst 33342 and to deduce the concentration of this fluorescent dye around both targeted and nontargeted cells. We believe that the method described herein will provide essential information regarding the specificity of cell targeting in any type of PLGA drug delivery system.
RESUMEN
BACKGROUND: We previously investigated fecal flora of the pouch after total proctocolectomy using terminal restriction fragment polymorphism analysis. Although the results of the cluster analysis demonstrated clearly that bacterial populations, including an unidentified bacteria generating a 213-bp PCR fragment, moved toward a colon-like community in the pouch, it did not track changes in the individual species of fecal bacteria. AIMS: The aim of the present study was to estimate genome copy number of ten bacterial species, clusters, groups, or subgroups (including the bacteria generating 213-bp fragment in the previous study) in feces samples from pouches at various times following ileostomy closure. METHODS: A total of 117 stool samples were collected from patients with ulcerative colitis after surgery as well as healthy volunteers. We used real-time polymerase chain reaction of the 16S rRNA gene to estimate genome copy numbers for the nine bacterial populations and the bacteria generating 213-bp fragment after identification by DNA sequencing. RESULTS: We demonstrated a time-dependent increase in the number of anaerobic and colon-predominant bacteria (such as Clostridium coccoides, C. leptum, Bacteroides fragilis and Atopobium) present in proctocolectomy patients after stoma closure. In contrast, numbers of ileum-predominant bacterial species (such as Lactobacillus and Enterococcus faecalis) declined. CONCLUSIONS: Our data confirm previous findings that fecal flora in the pouch after total proctocolectomy changes significantly, and further demonstrate that the number and diversity of ileal bacteria decreases while a more colon-like community develops. The present data are essential for the future analysis of pathological conditions in the ileal pouch.
