Folate-coated, long-circulating and pH-sensitive liposomes enhance doxorubicin antitumor effect in a breast cancer animal model

Long circulating pH-sensitive liposomes have been shown to effectively deliver doxorubicin (DOX) to tumors and reduce its toxic effects. Folic acid receptors are upregulated in a wide variety of solid, epithelial tumors, including breast cancer. In order to improve liposomal endocytosis and antitumor activity, folic acid has been added to nanoparticles surfaces to exploit overexpression of folate receptors in tumor cells. The purpose of this study was to evaluate the antitumor activity in vitro and in vivo of long circulating pH-sensitive folate-coated DOX-loaded liposomes (SpHL-DOX-Fol) in a 4T1 breast cancer model system in vitro and in vivo. Biodistribution studies were performed and in vivo electrocardiographic parameters were evaluated. A higher tumor uptake for radiolabeled SpHL-Fol (^99mTc-SpHL-Fol) 4 h after intravenous administration was observed in comparision with non-folate-coated liposomes (^99mTc-SpHL). Antitumor activity showed that SpHL-DOX-Fol treatment led to a 68% growth arrest and drastically reduce pulmonary metastasis foci. Additionally, eletrocardiographic parameters analysis revealed no dispersion in the QT and QTc interval was observed in liposomal treated mice. In summary, this novel multifunctional nanoplatform deomonstrated higher tumor uptake and antitumor activity. SpHL-DOX-Fol represents a drug delivery platform to improve DOX tumor delivery and reduce dose-limiting toxicity.

Synthesis, characterization and radiolabeling of polymeric nano-micelles as a platform for tumor delivering

The use of nanoparticles for diagnostic approaches leads to higher accumulation in the targeting tissue promoting a better signal-to-noise ratio and consequently, early tumor detection through scintigraphic techniques. Such approaches have inherent advantages, including the possibility of association with a variety of gamma-emitting radionuclides available, among them, Tecnethium-99m (^99mTc). ^99mTc is readily conjugated with nanoparticles using chelating agents, such as diethylenetriaminepentaacetic acid (DTPA). Leveraging this approach, we synthesized polymeric micelles (PM) consisting of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-mPEG₂₀₀₀) functionalized with DTPA for radiolabeling with ^99mTc. Micelles made up of DSPE-mPEG₂₀₀₀ and DSPE-PEG₂₀₀₀-DTPA had a mean diameter of  ∼10nm, as measured by DLS and SAXS techniques, and a zeta potential of -2.7±1.1mV. Radiolabeled micelles exhibited high radiochemical yields and stability. In vivo assays indicated long blood circulation time (456.3min). High uptake in liver, spleen and kidneys was observed in the biodistribution and imaging studies on healthy and tumor-bearing mice. In addition, a high tumor-to-muscle ratio was detected, which increased over time, showing accumulation of the PM in the tumor region. These findings indicate that this system is a promising platform for simultaneous delivery of therapeutic agents and diagnostic probes.

Doxorubicin-loaded pH-sensitive micelles: A promising alternative to enhance antitumor activity and reduce toxicity

Doxorubicin (DOX) is an anthracycline antibiotic widely used in the treatment of cancer, however, it is associated with the occurrence of adverse reactions that limits its clinical use. In this context, the encapsulation of DOX in micelles responsive to pH variations has shown to be a strategy for tumor delivery of the drug, with the potential to increase therapeutic efficacy and to reduce the toxic effects. In addition, radiolabeling nanoparticles with a radioactive isotope is of great use in preclinical studies, since it allows the in vivo monitoring of the nanostructure through the acquisition of quantitative images. Therefore, this study aimed to develop, characterize, and evaluate the antitumor activity of a pH-sensitive micelle composed of DSPE-PEG₂₀₀₀, oleic acid, and DOX. The micelles had a diameter of 13 nm, zeta potential near to neutrality, and high encapsulation percentage. The critical micellar concentration (CMC) was 1.4 × 10^-5 mol L^-1. The pH-sensitivity was confirmed in vitro through a drug release assay. Cytotoxicity studies confirmed that the encapsulation of DOX into the micelles did not impair the drug cytotoxic activity. Moreover, the incorporation of DSPE-PEG₂₀₀₀-DTPA into the micelles allowed it radiolabeling with the technetium-99 m in high yield and stability, permitting its use to monitor antitumor therapy. In this sense, the pH-sensitive micelles were able to inhibit tumor growth significantly when compared to non-pH-sensitive micelles and the free drug. in vivo toxicity evaluation in the zebrafish model revealed significantly lower toxicity of pH-sensitive micelles compared to the free drug. These results indicate that the developed formulation presents itself as a promising alternative to potentiate the treatment of tumors.

Effect of an impaired oral stage on swallowing in patients with Parkinson's disease

We investigated the swallowing function in patients with Parkinson's disease (PD) using deteriorated tongue control because patients with PD frequently exhibit an impaired oral stage of swallowing and the tongue movement affects oral and pharyngeal stage. In total, 201 patients with PD (106 men, 95 women; mean age 70·6 ± 8·0 years; median Hoehn-Yahr Stage III) were studied. The patients swallowed 10 mL of liquid barium under videofluorography, and their oral transit time (OTT) was measured. Based on 20 healthy controls (mean age 70·3 ± 7·8 years) with an OTT + 2 standard deviation (0·89 + 2 × 0·46) of 1·81 s, the patients with PD were divided into 167 patients with an OTT < 1·81 s and 34 patients with an OTT ≥ 1·81 s. Swallowing function was compared between the groups and assessed using logistic regression analysis. The following factors were significantly associated with oral stage impairment in both groups: tongue-to-palate contact, tongue root-to-posterior pharyngeal wall contact, premature spillage into the pharynx, aspiration and onset of swallowing reflex. Logistic regression analysis showed that tongue root-to-posterior pharyngeal wall contact, onset of swallowing reflex and aspiration were independent factors. PD patients with prolonged OTT displayed poor lingual control and decreased range of motion of the tongue due to bradykinesia and rigidity. Such problems in the oral stage affected the subsequent pharyngeal stage of swallowing with aspiration. Lingual movement in the oral stage thus appears to play an important role in the sequential movement of swallowing in PD.

Aspects of the diagnosis, pathogenesis and epidemiology of canine parvovirus

Between 18 July 1980 and 2 January 1981, 188 samples (145 faeces and 43 intestinal contents) were submitted from dogs with suspected canine parvovirus (CPV) enteritis. CPV was demonstrated in 56 (30%) of these samples; the weekly rate of positive CPV identification was remarkably constant at approximately 30% even though clinical and often post-mortem findings strongly supported a diagnosis of CPV enteritis. The simplest, most sensitive and most rapid method for detection of virus was haemagglutination (HA) which was twice as sensitive as isolation of virus and 8 times as sensitive as electron microscopy (EM). Forty nine of 56 (88%) samples positive for CPV were from dogs less than 1 year old and 44 (79%) CPV-positive samples were from pups less than 6 months old; only one sample from a pup less than 2 months old (pup was 7 weeks old) was positive. An additional 68 samples (53 faeces and 15 intestinal contents) were submitted from Beagle dogs that were part of a colony of approximately 1200 dogs. Epidemiological data pinpoints the entry of CPV into the colony in November 1978 at which time most dogs including pups less than 6 months of age developed antibody to CPV without developing clinical disease. From these data an overview of some aspects of the pathogenesis and epidemiology of CPV is constructed.

Denaturation of bovine liver glutamate dehydrogenase by guanidine hydrochloride. Correlation between enzymatic activity and molecular state

Bovine liver glutamate dehydrogenase (GDH), a hexameric enzyme, undergoes subunit dissociation, denaturation, and inactivation in the presence of guanidine hydrochloride (GdnHCl), depending on the denaturant concentration. The correlation between the enzymatic activity and the molecular state of GDH, and the reconstitution of native hexamer from subunits after the removal of GdnHCl were examined by measuring the enzymatic activity and CD spectrum in the far ultraviolet region. It was found that only the hexameric form of GDH has enzymatic activity, and the reconstitution of the hexamer with full enzymatic activity from the trimeric form which has native polypeptide chain structure can be achieved by the removal of GdnHCl. On the other hand, the recovery of enzymatic activity from the dissociated form in more concentrated GdnHCl solution where unfolding of the polypeptide chain takes place showed an exponential decrease with increasing incubation time in the GdnHCl solution. The time constant for the decay of enzymatic activity with respect to the incubation time was almost the same as that for unfolding of the polypeptide chain (followed by CD spectroscopy). It is suggested on the basis of these experimental results that the failure of reconstitution of GDH hexamer from subunits produced at high denaturant concentration is due to failure in the refolding of the unfolded subunit to the correct three-dimensional structure of the polypeptide chain rather than in the reassociation process from subunits.

Expression of rac1 protein in the crypt-villus axis of rat small intestine: in reference to insulin action

The expression of rho family along the crypt-villus axis of rat small intestine was investigated. The immunoblot analysis showed that the content of rac1 protein gradually increased from tip-villus to crypt-villus enterocytes without changes in the contents of rhoA and rac2 proteins. Furthermore, the contents of rac1 protein in the entire enterocytes were markedly decreased in streptozotocin-induced diabetic rats and restored by short-term treatment with insulin. These results suggest that differentiation and proliferation in the enterocytes of rat small intestine are possibly related to the expression of rac1 protein through insulin action.

Physical and biological effects of paclitaxel encapsulation on disteraroylphosphatidylethanolamine-polyethyleneglycol polymeric micelles

Simple size observations of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-mPEG2000) polymeric micelles (PM) with different compositions including or not paclitaxel (PTX) are unable to evidence changes on the nanocarrier structure. In such system a detailed characterization using highly sensitive techniques such as X-ray scattering and asymmetric flow field flow fractionation coupled to multi-angle laser light scattering and dynamic light scattering (AF4-MALS-DLS) is mandatory to observe effects that take place by the addition of PTX and/or more lipid-polymer at PM, leading to complex changes on the structure of micelles, as well as in their supramolecular organization. SAXS and AF4-MALS-DLS suggested that PM can be found in the medium separately and highly organized, forming clusters of PM in the latter case. SAXS fitted parameters showed that adding the drug does not change the average PM size since the increase in core radius is compensated by the decrease in shell radius. SAXS observations indicate that PEG conformation takes place, changing from brush to mushroom depending on the PM composition. These findings directly reflect in in vivo studies of blood clearance that showed a longer circulation time of blank PM when compared to PM containing PTX.

Encapsulating paclitaxel in polymeric nanomicelles increases antitumor activity and prevents peripheral neuropathy

Paclitaxel (PTX) has a great clinical significance as an antitumor drug, although several side effects are strongly dose-limiting. In this way, we prepared a PTX-loaded 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000] polymeric micelles (PM/PTX) in an attempt to improve safety and effectiveness of conventional PTX formulation (CrEL/EtOH/PTX). In this study, we evaluated from both formulations: stability after dilution, hemocompatibility, cellular uptake, acute toxicity in healthy mice, antitumor activity, and toxicity after multiple-dose treatment. PM/PTX appeared to be more stable than CrEL/EtOH/PTX after dilution. PM/PTX did not exhibit hemolytic activity (values <1%), even at high concentrations. In vitro cellular uptake study indicated that polymeric micelles were able to deliver more PTX (5.8 %) than CrEL/EtOH (2.7 %) to 4T1 cells. In the acute toxicity evaluation in healthy mice, CrEL/EtOH/PTX (single dose of 20 mg/kg) induced peripheral neuropathy, which was not observed in PM/PTX group. Similar results were observed after tumor-bearing mice received a multiple-dose regimen (seven doses of 10 mg/kg). Worth mentioning, we also evaluated vehicles, and CrEL/EtOH alone was not capable of inducing neuropathic pain. Besides, PM/PTX exhibited a higher antitumor activity with an inhibition ratio approximately 1.5-fold higher than CrEL/EtOH/PTX group. This study suggested that PM/PTX is safer than CrEL/EtOH/PTX, and was able to improve the antitumor effectiveness in a 4T1 breast cancer model.