Preparation,characterization, and antibacterial activity of diclofenac-loaded chitosan nanoparticles

Emerging antibiotic resistance necessitates the development of new therapeutic approaches. Many studies have reported the antimicrobial activity of diclofenac sodium (DIC) and chitosan nanoparticles (CNPs). Hence, this study aimed to prepare non-antibiotic DIC-loaded CNPs (DIC.CNPs) and characterize their in vitro antibacterial activity. DIC.CNPs were prepared from low and high molecular weight (LMW and HMW, respectively) chitosan using an ionic gelation method. Prepared NPs were characterized, and their antibacterial activity against gram-positive Staphylococcus aureus and Bacillus subtilis was evaluated using the agar diffusion and broth dilution methods. The particle size, polydispersity index (PDI), and encapsulation efficiency of the formulated DIC.CNPs increased with increasing MW of chitosan. The prepared NPs showed a narrow size distribution with low PDI values (0.18 and 0.24) and encapsulation efficiency (29.3% and 31.1%) for LMW.DIC.CNPs and HMW.DIC.CNPs, respectively. The in vitro release profile of DIC from the DIC.CNPs was biphasic with a burst release followed by slow release and was influenced by the MW of chitosan. DIC.CNPs exhibited significantly higher antibacterial activity against S. aureus (minimum inhibitory concentration [MIC₉₀] _LMW.DIC.CNPs?=?35?µg/mL and MIC_{90 HMW.DIC.CNPs}?=?18?µg/mL) and B. subtilis (MIC_{90 LMW.DIC.CNPs}?=?17.5?µg/mL and MIC_{90 HMW.DIC.CNPs}?=?9?µg/mL) than DIC alone did (MIC_{90 DIC}?=?250 and 50?µg/mL against S. aureus and B. subtilis, respectively). The antibacterial activity was influenced by pH and the MW of chitosan. Collectively, these results may suggest the potential usefulness of DIC.CNPs as non-antibiotic antibacterial agent necessitating further future studies to asses the stability of DIC.CNPs prepared.     

Carbon nanotube-based substrates for modulation of human pluripotent stem cell fate

We investigated the biological response of human pluripotent stem cells (hPSCs) cultured on a carbon nanotube (CNT) array-based substrate with the long term goal to direct hPSC germ layer specification for a wide variety of tissue engineering applications. CNT arrays were fabricated using a chemical vapor deposition system allowing for control over surface roughness and mechanical stiffness. Our results demonstrated that hPSCs readily attach to hydrophilized and extracellular matrix coated CNT arrays. hPSCs cultured as colonies in conditions supporting self-renewal demonstrated the morphology and marker expression of undifferentiated hPSCs. Conditions inducing spontaneous differentiation lead to hPSC commitment to all three embryonic germ layers as assessed by immunostaining and RT-PCR analysis. Strikingly, the physical characteristics of CNT arrays favored mesodermal specification of hPSCs. This is contradictory to the behavior of hPSCs on traditional tissue culture plastic which promotes the development of ectoderm. Altogether, these results demonstrate the potential of CNT arrays to be used in the generation of new platforms that allow for precise control of hPSC differentiation by tuning the characteristics of their physical microenvironment.     

Treatment of Melasma with Intralesional Tranexamic Acid Versus Cryotherapy

Background Melasma is a relatively common, acquired facial skin disorder of hyperpigmentation. Though it occurs in both sexes, nearly 90% of patients are female. It manifests as hyperpigmented macules and patches distributed symmetrically on the face, neck, and, rarely, the upper limbs. OBJECTIVE: The aim of this study was to evaluate and compare the clinical efficacy and adverse effects of intralesional injection of tranexamic acid (TA) versus cryotherapy in the treatment of melasma.MethodsPatients were divided into two groups: Group A and Group B. Group A comprised 28 patients aged 27 to 50 years. They received localized intralesional injections of TA. According to Wood’s light examination, patients were divided into two subtypes; 13 patients with mainly dermal-type melasma and 15 patients with mainly mixed-type melasma. Family history was obtained in 12 patients. Group B comprised 28 patients aged 29 to 46 years were included. They were treated with cryotherapy. According to Wood’s light examination, the patients were divided into two subtypes of melasma; 8 patients with mainly dermal-type melasma and 10 patients with mainly mixed-type melasma.ResultsThere were no statistically significant differences between Group A and Group B according to contraception, sun exposure, and family history. There was a statistically significant difference between Group A and Group B according to previous treatment. There was no statistically significant difference between the two groups according to drug allergy. There were no statistically significant differences according to systemic disease or general examination.ConclusionIntralesional tranexamic acid is a safe and effective method for the treatment of melasma with no risk of PIH, thrombosis, or bleeding; however, more sessions with longer follow-up periods are recommended, as the final response may take several months to occur. Cryotherapy was neither safe nor effective due to the risk of PIH.     

Metastatic papillary cancer of the neck: a diagnostic dilemma.

The finding of papillary carcinoma in a neck mass usually leads to the presumptive diagnosis of metastatic thyroid carcinoma, with total thyroidectomy revealing the primary tumor. We report five cases of metastatic papillary carcinoma of the neck. The primary tumor in three of the cases was found to be nonthyroidal; two being discovered only after thyroidectomy failed to reveal a primary cancer. In the two thyroidal neoplasms, pathologic examination of the thyroid demonstrated only minimal tumor in one case and no detectable tumor in the other. These cases illustrate the pitfalls of diagnosis and treatment of these tumors and the utility of antithyroglobulin immunostaining in such cases.     

"Early-peak" carbon monoxide production in certain erythropoietic disorders

The "early-labeled" peak (ELP) of 14CO excretion following injection of glycine-2-14C was used to study erythropoiesis in a patient with sideroblastic anemia and in four subjects with myeloproliferative disorders. The ELP was greatly enlarged in all patients, as compared with a normal volunteer. The contour of the peaks from the hematologically abnormal subjects suggested the presence of increased erythroid heme degradation. In the patient with sideroblastic anemia, all hours of the early peak were significantly reduced after transfusion. This was interpreted to mean that even the earliest or "nonerythroid" phase of the peak is influenced by erythropoietic activity, at least under conditions of erythropoietic stress.