Observations in simultaneous microencapsulation of 5-fluorouracil and leucovorin for combined pH-dependent release.

5-Fluorouracil (5-FU) in combination with leucovorin (LV) is nowadays the standard treatment in colon cancer and would be a candidate to be delivered orally to the colon. Eudragit P-4135F or Eudragit RS100 were used separately to prepare microspheres by an oil/oil emulsification process trapping 5-FU and LV simultaneously. Scanning electron microscopy permitted a structural analysis, process parameters were analyzed and drug loading and release profiles were recorded. Particle size varied between 123 (RS100) and 146 microm (P-4135F). Generally, higher encapsulation rates were found with RS100 (5-FU, 60.3+/-9.7%; LV, 81.4+/-8.6%) compared to P-4135F (5-FU, 48.3+/-2.0%; LV, 55.4+/-2.7%). Microparticles made from Eudragit RS100 released the incorporated drug combination within 8 h not exhibiting general differences between the kinetics of both drugs. P-4135F was found to maintain the undesired 5-FU release at pH 6.8 lower than 25% within 4 h while at pH 7.4, a nearly immediate release (within 15 min) was observed. Although the release was similar at pH 7.4, at pH 6.8 LV showed a distinct initial drug loss of about 60% and a complete release within 2 h. SEM analyses revealed a substantial presence of LV crystals on the particle surface provoking a distinct burst effect of LV. These observations were concluded to be related to the high lipophilicity of P-4135F provoking a separation between P-4135F and LV during the preparation process.     

A pH-sensitive microsphere system for the colon delivery of tacrolimus containing nanoparticles.

Nanoparticles (NP) are known to accumulate at the site of inflammation in inflammatory bowel disease. In order to avoid premature uptake or degradation of NP during their passage through the small intestine, it appeared necessary to devise a form of local delivery system for NP. Tacrolimus (FK506) loaded poly(lactic-co-glycolic acid) NP entrapped into pH-sensitive microspheres (NPMS) were designed to achieve greater selectivity to their site of action when administered orally. The therapeutic efficacy of this drug delivery system was tested in an experimental colitis in rats. The in vitro characterization showed a successful incorporation of FK506-NP and strongly pH-sensitive release kinetics of both NP and drug. During the in vivo studies, clinical activity, colon/body weight index, and myeloperoxidase activity were determined to assess the severity of inflammation. Systemic availability of a fluorescent dye entrapped in the microspheres was measured in order to determine possible adverse effects. The NPMS as well as the controls of NP and MS formulations exhibited significant mitigating effects in the clinical activity index after 3 days of treatment with similar levels for the various therapies. When observing colon/body weight index and myeloperoxidase activity, only the NPMS group reached statistically significant differences (P<0.05) compared to the colitis control group while other groups did not (colitis control: 21.94+/-4.97; FK506 solution: 15.81+/-3.42; FK506-NP: 17.03+/-5.52; FK506-MS: 15.17+/-7.81; and FK-NPMS: 10.26+/-7.76 U/mg tissue). Moreover, the NPMS system reduced the systemic absorption of the entrapped dye compared to the dye solution or simple NP formulation (relative biovailability-solution: 100+/-14.9%; NP: 46.8+/-8.6%; and NPMS: 29.4+/-3.3%). The results suggest that the NPMS system can provide selective delivery of NP in the colon and develop a significant mitigating effect, while the control group treatments appeared to be insufficient.     

A-kinase anchoring proteins in amygdala are involved in auditory fear memory

A-kinase anchoring proteins (AKAPs) constitute a family of scaffolding proteins that bind the regulatory subunits of protein kinase A (PKA). AKAP binding to PKA regulates the phosphorylation of various proteins, some of which have been implicated in synaptic plasticity and memory consolidation. Here we show that the regulatory subunits of PKA are colocalized with AKAP150 (an AKAP isoform that is expressed in the brain) in the lateral amygdala (LA) and that infusion to the LA of the peptide St-Ht31, which blocks PKA anchoring onto AKAPs, impairs memory consolidation of auditory fear conditioning.     

High rates of clustering of strains causing tuberculosis in Harare, Zimbabwe: a molecular epidemiological study

We examined the pattern of tuberculosis (TB) transmission (i.e., reactivation versus recent transmission) and the impact of human immunodeficiency virus (HIV) infection in Harare, Zimbabwe. Consecutive adult smear-positive pulmonary TB patients presenting to an urban hospital in Harare were enrolled. A detailed epidemiological questionnaire was completed, and tests for HIV type 1 and CD4 cell counts were performed for each patient. Molecular fingerprinting of the genomic DNA recovered from cultures of sputum was performed by two molecular typing methods: spacer oligonucleotide typing (spoligotyping) and analysis of variable number of tandem DNA repeats (VNTRs). A cluster was defined as isolates from two or more patients that shared the same spoligotype pattern or the same VNTR pattern, or both. DNA suitable for typing was recovered from 224 patients. The prevalence of HIV infection was 79%. Of 187 patient isolates (78.6%) typed by both spoligotyping and analysis of VNTRs, 147 were identified as part of a cluster by both methods. By spoligotyping alone, 84.1% of patient isolates were grouped into 20 clusters. The cluster size was generally <8 patient isolates, although three large clusters comprised 68, 25, and 23 patient isolates. A total of 89.4% of the patient isolates grouped into 12 clusters defined by analysis of VNTRs, with 2 large clusters consisting of 127 and 13 patient isolates, respectively. Thirty-six percent of patient isolates with a shared spoligotype and 17% with a shared VNTR pattern were geographically linked within Harare, but they were not linked on the basis of the patient's home district. In a multivariate analysis, there were no independent predictors of clustering, including HIV infection status. Comparison with the International Spoligotype database (Pasteur Institute, Pointe a Pitre, Guadeloupe) demonstrated that our three largest spoligotype clusters are well recognized and ubiquitous in Africa. In this epidemiologically well characterized urban population with a high prevalence of HIV infection, we identified a very high level of strain clustering, indicating substantial ongoing recent TB transmission. Geographic linkage could be detected in a proportion of these clusters. A small group of actively circulating strains accounted for most of the cases of TB transmission.     

October 2001: 40-year-old Xhosa male with back pain and leg weakness

A 40-year-old Xhosa male presented with progressive upper lumbar back pain and weakness At examination he was emaciated and had enlarged lymph nodes in the groin and axilla. Both lower limbs were severely atrophic and weak. Sensation to touch and pain was decreased below L3 bilaterally. MR of the spine showed a discrete, contrast-enhancing epidural mass. A T10-T12 laminectomy revealed an soft, vascular extradural tumor dorsal to the cord. The mass was loosely applied to the dura and easy to remove. The operative specimen consisted of a sausage-shaped (3.5 x 2.0 x 1.2 cm), thinly-encapsulated mass of reddish-brown tissue. The cut surface had a mottled, vaguely nodular, yellowish-brown appearance. Microscopic examination revealed sheets of hematopoeitic elements, including myeloid, red cell and megakaryocytic lines, the latter showing Factor 8-related positivity. The final diagnosis was extramedullary hematopoiesis (EMH). A bone marrow biopsy performed as a result of the diagnosis showed a myeloproliferative disease and polycythemia vera. EMH in the spinal epidural space is a rare but treatable cause of progressive paraparesis in patients with a variety of hematological disorders. Since 1956 there have been more than 50 reported cases, most of which occurred in association with thalassaemia. In spinal cord compression secondary to EMH, the lesions are commonly localized to the mid-lower thoracic region.     

Polydactyly of the foot

Polydactyly may be preaxial or tibial (hallux-side), postaxial or ulnar (side of the little toe) and central (middle toes). The duplication may appear at the distal and medial phalanges or at the whole digit. The metatarsal bone may be part wise or completely duplicated, the accessory toes may share only one metatarsal. Surgical intervention may be indicated in shoe problems, for esthetic reasons or, especially in duplication of the metatarsales, because of secondary deviation of the toes and therefore shoe problems or plantar callosities. Preoperative analysis including x-ray is of great importance to achieve good functional and cosmetic results.