Critical Solvent Properties Affecting the Particle Formation Process and Characteristics of Celecoxib-Loaded PLGA Microparticles via Spray-Drying

Purpose

It is imperative to understand the particle formation mechanisms when designing advanced nano/microparticulate drug delivery systems. We investigated how the solvent power and volatility influence the texture and surface chemistry of celecoxib-loaded poly (lactic-co-glycolic acid) (PLGA) microparticles prepared by spray-drying.

Methods

Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA).

Results

Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures.

Conclusions

The particle formation process is mainly governed by the PLGA precipitation rate, which is solvent-dependent, and the migration rate of celecoxib molecules during drying. The texture and surface chemistry of the spray-dried PLGA microparticles can therefore be tailored by adjusting the solvent composition.

Mre11 inhibition by oncolytic adenovirus associates with autophagy and underlies synergy with ionizing radiation

New treatment approaches are needed for hormone refractory prostate cancer. Oncolytic adenoviruses are promising anti‐cancer agents, and their efficacy can be improved by combining with conventional therapies such as ionizing radiation. The aim of this study was to determine the timing of oncolytic adenovirus treatment with regard to radiation and study the mechanisms of synergy in combination treatment. Prostate cancer cells were infected with oncolytic adenoviruses, irradiated and synergy mechanisms were assessed. In vivo models of combination treatment were tested. Radiation and oncolytic viruses were synergistic when viral infection was scheduled 24 hr after irradiation. Combination of oncolytic adenovirus with radiotherapy significantly increased antitumor efficacy in vivo compared to either agent alone. Microarray analysis showed dysregulated pathways including cell cycle, mTOR and antigen processing pathways. Functional analysis showed that adenoviral infection was accompanied with degradation of proteins involved in DNA break repair. Mre11 was degraded for subsequent inactivation of Chk2‐Thr68 in combination treated cells, while γH2AX‐Ser139 was elevated implicating the persistence of DNA double strand breaks. Increased autophagocytosis was seen in combination treated cells. Combination treatment did not increase apoptosis or virus replication. The results provide evidence of the antitumor efficacy of combining oncolytic adenoviruses with irradiation as a therapeutic strategy for the treatment of prostate cancer. Further, these findings propose a molecular mechanism that may be important in radiation induced cell death, autophagy and viral cytopathic effect. © 2009 UICC     

Clostridium difficile genotyping based on slpA variable region in S-layer gene sequence: an alternative to serotyping

Recent investigations of Clostridium difficile cell wall components have revealed the presence of an S-layer encoded by the slpA gene. The aim of this study was to determine whether slpA genotyping can be used as an alternative to serotyping. The variable regions of slpA were amplified by PCR from serogroup reference strains and various clinical isolates chosen randomly. Amplified products were analyzed after restriction enzyme digestion and DNA sequencing. The sequences of the variable region of the SlpA protein were found to be strictly identical within a given serogroup but divergent between serogroups. These preliminary results suggest that PCR-restriction fragment length polymorphism, in conjunction with DNA sequencing of the slpA variable region, could constitute an alternative typing method for determining C. difficile serotypes.     

Interleukin-6 promoter polymorphism and late-onset Alzheimer's disease in the Finnish population

Recently, the involvement of the inflammatory response in Alzheimer's disease (AD) has received considerable attention. The gene encoding for interleukin-6 (IL-6) is interesting since IL-6 has been reported not only to be involved in immune functions but also in AD. We investigated whether the IL-6-174 G/C polymorphism is associated with late onset AD (LOAD) in the Finnish subjects. The G allele was over-represented in ApoE4-LOAD patients but remained unimportant in all and in the ApoE E4 carriers. Interestingly, the G allele frequency was lower in our population in both AD patients and in controls compared to Southern European populations.     

Fatal and life-threatening complications in antireflux surgery: analysis of 5,502 operations

BACKGROUND: There have been few comprehensive studies relating to the life-threatening or fatal complications of antireflux surgery. METHODS: Some 5502 antireflux operations were performed in Finland between January 1987 and January 1996 (population approximately 5 million); 3993 procedures (72.6 per cent) were open fundoplications, 1162 (21.1 per cent) laparoscopic fundoplications and 347 (6.3 per cent) other anti-reflux procedures. RESULTS: There were 43 fatal or life-threatening complications (prevalence 0.8 per cent). Twenty-two followed primary open fundoplication (prevalence 0.6 per cent), 15 laparoscopic fundoplication (prevalence 1.3 per cent) (P < 0.05), one refundoplication and five other antireflux procedures. The overall mortality rate was 0.3 per cent. Nine patients (0.2 per cent) died after open fundoplication, one (0.1 per cent) following laparoscopic fundoplication (P = 0.43), one following refundoplication and four after other antireflux procedures. Laparoscopic fundoplication was followed by 14 non-fatal life-threatening complications (prevalence 1.2 per cent), open fundoplication by 13 (prevalence 0.3 per cent) (P < 0.01) and other antireflux procedures by one life-threatening complication (0.3 per cent). CONCLUSION: Laparoscopic fundoplication was associated with more life-threatening complications than open fundoplication. This may compromise the advantages of the laparoscopic technique.     

Molecular Diagnosis of Human Rhinovirus Infections: Comparison with Virus Isolation

To compare the sensitivity and specificity of RT-PCR with that of virus isolation in the detection of human rhinoviruses, we tested nasopharyngeal aspirates from 200 patients on the 1st and 7th days after the onset of the common cold. An assay utilizing a short amplicon in the conserved 5′ noncoding region was found highly sensitive. Of 192 positive samples altogether, 65 were found positive by RT-PCR only, 6 were positive by isolation exclusively, and 121 gave positive results in both tests.     

Viruses and Bacteria in the Etiology of the Common Cold

Two hundred young adults with common colds were studied during a 10-month period. Virus culture, antigen detection, PCR, and serology with paired samples were used to identify the infection. Viral etiology was established for 138 of the 200 patients (69%). Rhinoviruses were detected in 105 patients, coronavirus OC43 or 229E infection was detected in 17, influenza A or B virus was detected in 12, and single infections with parainfluenza virus, respiratory syncytial virus, adenovirus, and enterovirus were found in 14 patients. Evidence for bacterial infection was found in seven patients. Four patients had a rise in antibodies against Chlamydia pneumoniae, one had a rise in antibodies against Haemophilus influenzae, one had a rise in antibodies against Streptococcus pneumoniae, and one had immunoglobulin M antibodies against Mycoplasma pneumoniae. The results show that although approximately 50% of episodes of the common cold were caused by rhinoviruses, the etiology can vary depending on the epidemiological situation with regard to circulating viruses. Bacterial infections were rare, supporting the concept that the common cold is almost exclusively a viral disease.     

Severity of hand osteoarthritis and its association with upper extremity impairment in a population of disabled older women: the Women's Health and Aging Study

Most severity indices of osteoarthritis (OA) include measures of physical function which render them unsuitable for assessing the impact of OA on disability. Data from 1002 moderate to severely disabled community-dwelling women > or = 65 years were used to develop hand OA severity indices which are independent of functional status. Baseline exams and strength tests were conducted by trained nurse examiners. Each distal and proximal interphalangeal joint, and first carpometacarpal joint (20 joints in all) was scored for the presence of a) bony enlargement or deformity, and b) pain on motion or tenderness on palpation. Severity indices were then created: Deformity index (DEF) = sum of joints with bony changes (0-20); Pain/Tenderness index (PT) = sum of joints with pain or tenderness (0-20); and Combined Deformity/Pain index = sum of DEF and PT (0-40). These indices were then validated against grip and pinch strength. All three indices showed a significant trend for weaker grip strength as severity index scores increased. When the 25th, 50th and 75th percentiles were used to divide each severity index into levels of involvement, a threshold effect was observed with significantly poorer grip strength performance above the 75th percentile for each index. Similar results were seen for pinch strength. In conclusion, these hand OA severity indices, based on examination findings alone, help distinguish disease status, and may provide a valuable research tool for investigating the role of hand OA in impairment and disability.     

Depressed mood and body mass index as predictors of muscle strength decline in old men

OBJECTIVE: To study depressed mood as a predictor of strength decline within body weight categories over a 3-year follow-up period. DESIGN: A prospective cohort study over 3 years. SETTING: Honolulu, Hawaii. PARTICIPANTS: The subjects were 2275 men participating in the Honolulu Heart Program with an average age of 77.1 years (range 71-92 years), who were not cognitively impaired at baseline (Exam 4), and who participated in maximal hand grip strength measurements at baseline and 3 years later (Exam 5). MEASUREMENTS: Hand grip strength was measured using a dynamometer. Depressive symptoms were studied using an 11-item version of Center for Epidemiologic Studies Depression Scale with 9 as a cutoff. Body weight categories were formed on the basis of body mass index (BMI) (BMI = weight/height2; underweight: BMI < 20; normal weight: BMI 20-24.99, overweight: BMI > or = 25). MAIN RESULTS: At baseline, 9.4% of the participants were rated as having depressed mood. The mean individual strength change over 3 years was - 6.9% (standard deviation 14.0). Steep strength decline was determined as losing > or = 14% (lowest quartile). The proportions of those with steep strength decline in the groups based on combined distributions of BMI and depressed mood were: underweight/ depressed (n = 22) 41%, underweight/not depressed (n = 200) 28%, normal weight/depressed (n = 127) 30%, normal weight/not depressed (n = 1181) 25%, overweight/depressed (n = 55) 31%, overweight/not depressed (n = 675, referent) 21%. After adjusting for baseline strength, age, height, sociodemographic variables and diseases, the odds ratio for steep strength decline was more than four times greater among those who were depressed and underweight, and twice as great among people who were depressed and normal weight compared with those who were nondepressed and overweight. The risks of nondepressed under- and normal weight people and depressed overweight people did not differ from the reference group. CONCLUSIONS: Depressed mood was associated with increased risk of steep strength decline, in particular in older men with low body weight. Low body weight in combination with depressed mood may be an indicator of frailty or severe disease status that leads to accelerated strength loss and disability.     

Differences in the diagnosis of myocardial infarction by troponin T compared with clinical and epidemiologic criteria

We investigated the difference in the number of myocardial infarction (MI) diagnoses based on troponin T compared with clinical and epidemiologic (modified FINnish Multinational MONItoring of trends and determinants in CArdiovascular diseases) diagnoses, and the prognosis of patients with discordant diagnoses. Five hundred fifty-nine consecutive patients (315 men and 244 women, median age 69 years) were admitted to the hospital with a suspected acute coronary syndrome. Median follow-up time was 17 months. Of the 559 patients, 127 had a clinical and 137 an epidemiologic diagnosis of MI. When a diagnosis of MI was primarily based on troponin T (>0.10 microg/L), the number of MIs was 169, which increased by 33% compared with the number of MIs by clinical diagnosis, and by 23% compared with those by epidemiologic diagnosis. However, troponin T was not elevated in 13% of the 127 patients with the clinical diagnosis and in 14% of the 137 patients with the epidemiologic diagnosis of MI. Among patients in whom clinical diagnosis of MI was not made, the prognosis with regard to coronary death or nonfatal MI was not significantly worse in patients with troponin T >0.10 microg/L than < or =0.10 microg/L (hazard ratio 1.07; 95% confidence interval 0.62 to 1.84). In patients with a suspected acute coronary syndrome, troponin T-based diagnostics leads to an increase in the number of patients diagnosed with MI compared with clinical or epidemiologic diagnosis. The prognostic impact of troponin T in patients without clinical diagnosis of MI based on elevations in conventional enzyme activities needs further study in larger series of patients.