The genome sequence of Drosophila melanogaster

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

The design of scaffolds for use in tissue engineering. Part I. Traditional factors

In tissue engineering, a highly porous artificial extracellular matrix or scaffold is required to accommodate mammalian cells and guide their growth and tissue regeneration in three dimensions. However, existing three-dimensional scaffolds for tissue engineering proved less than ideal for actual applications, not only because they lack mechanical strength, but they also do not guarantee interconnected channels. In this paper, the authors analyze the factors necessary to enhance the design and manufacture of scaffolds for use in tissue engineering in terms of materials, structure, and mechanical properties and review the traditional scaffold fabrication methods. Advantages and limitations of these traditional methods are also discussed.

Functional gamma-secretase inhibitors reduce beta-amyloid peptide levels in brain

Converging lines of evidence implicate the beta-amyloid peptide (Ass) as causative in Alzheimer's disease. We describe a novel class of compounds that reduce A beta production by functionally inhibiting gamma-secretase, the activity responsible for the carboxy-terminal cleavage required for A beta production. These molecules are active in both 293 HEK cells and neuronal cultures, and exert their effect upon A beta production without affecting protein secretion, most notably in the secreted forms of the amyloid precursor protein (APP). Oral administration of one of these compounds, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester, to mice transgenic for human APP(V717F) reduces brain levels of Ass in a dose-dependent manner within 3 h. These studies represent the first demonstration of a reduction of brain A beta in vivo. Development of such novel functional gamma-secretase inhibitors will enable a clinical examination of the A beta hypothesis that Ass peptide drives the neuropathology observed in Alzheimer's disease.

Crystal structure of an IHF-DNA complex: a protein-induced DNA U-turn

Integration host factor (IHF) is a small heterodimeric protein that specifically binds to DNA and functions as an architectural factor in many cellular processes in prokaryotes. Here, we report the crystal structure of IHF complexed with 35 bp of DNA. The DNA is wrapped around the protein and bent by >160 degrees, thus reversing the direction of the helix axis within a very short distance. Much of the bending occurs at two large kinks where the base stacking is interrupted by intercalation of a proline residue. IHF contacts the DNA exclusively via the phosphodiester backbone and the minor groove and relies heavily on indirect readout to recognize its binding sequence. One such readout involves a six-base A tract, providing evidence for the importance of a narrow minor groove.

Genetic diversity and disease control in rice

Crop heterogeneity is a possible solution to the vulnerability of monocultured crops to disease. Both theory and observation indicate that genetic heterogeneity provides greater disease suppression when used over large areas, though experimental data are lacking. Here we report a unique cooperation among farmers, researchers and extension personnel in Yunnan Province, China--genetically diversified rice crops were planted in all the rice fields in five townships in 1998 and ten townships in 1999. Control plots of monocultured crops allowed us to calculate the effect of diversity on the severity of rice blast, the major disease of rice. Disease-susceptible rice varieties planted in mixtures with resistant varieties had 89% greater yield and blast was 94% less severe than when they were grown in monoculture. The experiment was so successful that fungicidal sprays were no longer applied by the end of the two-year programme. Our results support the view that intraspecific crop diversification provides an ecological approach to disease control that can be highly effective over a large area and contribute to the sustainability of crop production.

Direct analysis and identification of proteins in mixtures by LC/MS/MS and database searching at the low-femtomole level

A method to directly identify proteins contained in mixtures by microcolumn reversed-phase liquid chromatography electrospray ionization tandem mass spectrometry (LC/MS/MS) is studied. In this method, the mixture of proteins is digested with a proteolytic enzyme to produce a large collection of peptides. The complex peptide mixture is then separated on-line with a tandem mass spectrometer, acquiring large numbers of tandem mass spectra. The tandem mass spectra are then used to search a protein database to identify the proteins present. Results from standard protein mixtures show that proteins present in simple mixtures can be readily identified with a 30-fold difference in molar quantity, that the identifications are reproducible, and that proteins within the mixture can be identified at low femtomole levels. Based on these studies, methodology has been developed for direct LC/MS/MS analysis of proteins enriched by immunoaffinity precipitation, specific interaction with a protein-protein fusion product, and specific interaction with a macromolecular complex. The approach described in this article provides a rapid method for the direct identification of proteins in mixtures.

High prevalence of abnormal acid gastro-oesophageal reflux in idiopathic pulmonary fibrosis

The aim of this prospective study was to determine the prevalence and characteristics of acid gastro-oesophageal reflux (GER) in patients with idiopathic pulmonary fibrosis (IPF). Sixty-five consecutive patients with well-defined IPF were subjected to 24-h pH monitoring and oesophageal manometry. A total of 133 consecutive patients with intractable asthma and symptoms of GER were used as comparisons. The prevalence of abnormal acid GER in IPF patients was 87%, with 76% and 63% demonstrating abnormal distal and proximal oesophageal acid exposures, respectively. Abnormal acid GER was significantly more common in IPF patients than asthma patients. Only 47% of IPF patients experienced classic GER symptoms. Despite treatment with standard doses of proton pump inhibitors (PPIs), 12 out of 19 patients receiving PPIs during the 24-h pH monitoring had abnormal oesophageal acid exposures by pH probe. There was no correlation between IPF severity and acid GER severity. In conclusion, abnormal acid gastro-oesophageal reflux is highly prevalent, but often clinically occult in patients with idiopathic pulmonary fibrosis. Standard doses of proton pump inhibitors may not suppress the acid gastro-oesophageal reflux in this population. Therefore, further studies are needed to determine if acid abnormal gastro-oesophageal reflux represents an important risk factor for idiopathic pulmonary fibrosis development or progression, and if optimal suppression of acid gastro-oesophageal reflux slows the progression of idiopathic pulmonary fibrosis and/or decreases episodic exacerbations of idiopathic pulmonary fibrosis.

Peroxisome proliferator-activated receptor gamma ligands are potent inhibitors of angiogenesis in vitro and in vivo

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that functions as a transcription factor to mediate ligand-dependent transcriptional regulation. Activation of PPARgamma by the naturally occurring ligand, 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), or members of a new class of oral antidiabetic agents, e.g. BRL49653 and ciglitizone, has been linked to adipocyte differentiation, regulation of glucose homeostasis, inhibition of macrophage and monocyte activation, and inhibition of tumor cell proliferation. Here we report that human umbilical vein endothelial cells (HUVEC) express PPARgamma mRNA and protein. Activation of PPARgamma by the specific ligands 15d-PGJ2, BRL49653, or ciglitizone, dose dependently suppresses HUVEC differentiation into tube-like structures in three-dimensional collagen gels. In contrast, specific PPARalpha and -beta ligands do not affect tube formation although mRNA for these receptors are expressed in HUVEC. PPARgamma ligands also inhibit the proliferative response of HUVEC to exogenous growth factors. Treatment of HUVEC with 15d-PGJ2 also reduced mRNA levels of vascular endothelial cell growth factor receptors 1 (Flt-1) and 2 (Flk/KDR) and urokinase plasminogen activator and increased plasminogen activator inhibitor-1 (PAI-1) mRNA. Finally, administration of 15d-PGJ2 inhibited vascular endothelial cell growth factor-induced angiogenesis in the rat cornea. These observations demonstrate that PPARgamma ligands are potent inhibitors of angiogenesis in vitro and in vivo, and suggest that PPARgamma may be an important molecular target for the development of small-molecule inhibitors of angiogenesis.

Obesity induces expression of uncoupling protein-2 in hepatocytes and promotes liver ATP depletion

Uncoupling protein 2 (UCP2) uncouples respiration from oxidative phosphorylation and may contribute to obesity through effects on energy metabolism. Because basal metabolic rate is decreased in obesity, UCP2 expression is predicted to be reduced. Paradoxically, hepatic expression of UCP2 mRNA is increased in genetically obese (ob/ob) mice. In situ hybridization and immunohistochemical analysis of ob/ob livers demonstrate that UCP2 mRNA and protein expression are increased in hepatocytes, which do not express UCP2 in lean mice. Mitochondria isolated from ob/ob livers exhibit an increased rate of H+ leak which partially dissipates the mitochondrial membrane potential when the rate of electron transport is suppressed. In addition, hepatic ATP stores are reduced and these livers are more vulnerable to necrosis after transient hepatic ischemia. Hence, hepatocytes adapt to obesity by up-regulating UCP2. However, because this decreases the efficiency of energy trapping, the cells become vulnerable to ATP depletion when energy needs increase acutely.

Regulation of dendritic spine morphology by SPAR, a PSD-95-associated RapGAP

The PSD-95/SAP90 family of scaffold proteins organizes the postsynaptic density (PSD) and regulates NMDA receptor signaling at excitatory synapses. We report that SPAR, a Rap-specific GTPase-activating protein (RapGAP), interacts with the guanylate kinase-like domain of PSD-95 and forms a complex with PSD-95 and NMDA receptors in brain. In heterologous cells, SPAR reorganizes the actin cytoskeleton and recruits PSD-95 to F-actin. In hippocampal neurons, SPAR localizes to dendritic spines and causes enlargement of spine heads, many of which adopt an irregular appearance with putative multiple synapses. Dominant negative SPAR constructs cause narrowing and elongation of spines. The effects of SPAR on spine morphology depend on the RapGAP and actin-interacting domains, implicating Rap signaling in the regulation of postsynaptic structure.

Hepatocyte growth factor enhances vascular endothelial growth factor-induced angiogenesis in vitro and in vivo

Vascular endothelial growth factor (VEGF) is an important mediator of angiogenesis in both physiological and pathological processes. Hepatocyte growth factor (HGF) is a mesenchyme-derived mitogen that also stimulates cell migration, and branching and/or tubular morphogenesis of epithelial and endothelial cells. In the present study, we tested the hypothesis that simultaneous administration of HGF and VEGF would synergistically promote new blood vessel formation. HGF acted in concert with VEGF to promote human endothelial cell survival and tubulogenesis in 3-D type I collagen gels, a response that did not occur with either growth factor alone. The synergistic effects of VEGF and HGF on endothelial survival correlated with greatly augmented mRNA levels for the anti-apoptotic genes Bcl-2 and A1. Co-culture experiments with human neonatal dermal fibroblasts and human umbilical vein endothelial cells demonstrated that neonatal dermal fibroblasts, in combination with VEGF, stimulated human umbilical vein endothelial cells tubulogenesis through the paracrine secretion of HGF. Finally, in vivo experiments demonstrated that the combination of HGF and VEGF increased neovascularization in the rat corneal assay greater than either growth factor alone. We suggest that combination therapy using HGF and VEGF co-administration may provide a more effective strategy to achieve therapeutic angiogenesis.

Valproate protects dopaminergic neurons in midbrain neuron/glia cultures by stimulating the release of neurotrophic factors from astrocytes

Valproate (VPA), one of the mood stabilizers and antiepileptic drugs, was recently found to inhibit histone deacetylases (HDAC). Increasing reports demonstrate that VPA has neurotrophic effects in diverse cell types including midbrain dopaminergic (DA) neurons. However, the origin and nature of the mediator of the neurotrophic effects are unclear. We have previously demonstrated that VPA prolongs the survival of midbrain DA neurons in lipopolysaccharide (LPS)-treated neuron-glia cultures through the inhibition of the release of pro-inflammatory factors from microglia. In this study, we report that VPA upregulates the expression of neurotrophic factors, including glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) from astrocytes and these effects may play a major role in mediating VPA-induced neurotrophic effects on DA neurons. Moreover, VPA pretreatment protects midbrain DA neurons from LPS or 1-methyl-4-phenylpyridinium (MPP+)-induced neurotoxicity. Our study identifies astrocyte as a novel target for VPA to induce neurotrophic and neuroprotective actions in rat midbrain and shows a potential new role of cellular interactions between DA neurons and astrocytes. The neurotrophic and neuroprotective effects of VPA also suggest a utility of this drug for treating neurodegenerative disorders including Parkinson's disease. Moreover, the neurotrophic effects of VPA may contribute to the therapeutic action of this drug in treating bipolar mood disorder that involves a loss of neurons and glia in discrete brain areas.

Mitochondrial adaptations to obesity-related oxidant stress

It is not known why viable hepatocytes in fatty livers are vulnerable to necrosis, but associated mitochondrial alterations suggest that reactive oxygen species (ROS) production may be increased. Although the mechanisms for ROS-mediated lethality are not well understood, increased mitochondrial ROS generation often precedes cell death, and hence, might promote hepatocyte necrosis. The aim of this study is to determine if liver mitochondria from obese mice with fatty hepatocytes actually produce increased ROS. Secondary objectives are to identify potential mechanisms for ROS increases and to evaluate whether ROS increase uncoupling protein (UCP)-2, a mitochondrial protein that promotes ATP depletion and necrosis. Compared to mitochondria from normal livers, fatty liver mitochondria have a 50% reduction in cytochrome c content and produce superoxide anion at a greater rate. They also contain 25% more GSH and demonstrate 70% greater manganese superoxide dismutase activity and a 35% reduction in glutathione peroxidase activity. Mitochondrial generation of H(2)O(2) is increased by 200% and the activities of enzymes that detoxify H(2)O(2) in other cellular compartments are abnormal. Cytosolic glutathione peroxidase and catalase activities are 42 and 153% of control values, respectively. These changes in the production and detoxification of mitochondrial ROS are associated with a 300% increase in the mitochondrial content of UCP-2, although the content of beta-1 ATP synthase, a constitutive mitochondrial membrane protein, is unaffected. Supporting the possibility that mitochondrial ROS induce UCP-2 in fatty hepatocytes, a mitochondrial redox cycling agent that increases mitochondrial ROS production upregulates UCP-2 mRNAs in primary cultures of normal rat hepatocytes by 300%. Thus, ROS production is increased in fatty liver mitochondria. This may result from chronic apoptotic stress and provoke adaptations, including increases in UCP-2, that potentiate necrosis.

Synthetic-lethal interactions identify two novel genes, SLA1 and SLA2, that control membrane cytoskeleton assembly in Saccharomyces cerevisiae

Abplp is a yeast cortical actin-binding protein that contains an SH3 domain similar to those found in signal transduction proteins that function at the membrane/cytoskeleton interface. Although no detectable phenotypes are associated with a disruption allele of ABP1, mutations that create a requirement for this protein have now been isolated in the previously identified gene SAC6 and in two new genes, SLA1 and SLA2. The SAC6 gene encodes yeast fimbrin, an actin filament-bundling protein. Null mutations in SLA1 and SLA2 cause temperature-sensitive growth defects. Sla1p contains three SH3 domains and is essential for the proper formation of the cortical actin cytoskeleton. The COOH terminus of Sla2p contains a 200 amino acid region with homology to the COOH terminus of talin, a membrane cytoskeletal protein which is a component of fibroblast focal adhesions. Sla2p is required for cellular morphogenesis and polarization of the cortical cytoskeleton. In addition, synthetic-lethal interactions were observed for double-mutants containing null alleles of SLA2 and SAC6. In total, the mutant phenotypes, sequences, and genetic interactions indicate that we have identified novel proteins that cooperate to control the dynamic cytoskeletal rearrangements that are required for the development of cell polarity in budding yeast.

Cloning and characterization of an IGF-1 isoform expressed in skeletal muscle subjected to stretch

To ascertain if IGF-1 is a regulator of local muscle growth, total RNA was extracted from rabbit muscle induced to undergo rapid hypertrophy using active stretch and from control muscles. This was analysed by Northern hybridization with a 280 base pair probe containing sequences derived from exons 3 and 4 of the insulin-like growth factor 1 gene. Two types of insulin-like growth factor 1 mRNA were shown to be strong expressed in the stretched muscles. In situ hybridization using the same probe (280 base pair) showed that IGF-1 is strongly expressed in muscle that is induced to grow rapidly and is expressed in the muscle fibres themselves. Using RT-PCR a single insulin-like growth factor 1 isoform cDNA (IGF-1Ea) could be cloned from the normal resting muscles. However, an additional isoform of insulin-like growth factor 1 (insulin-like growth factor 1Eb) was found to be expressed in stretched muscle undergoing hypertrophy. The E domain sequence of the additional isoform differs from the liver insulin-like growth factor 1Ea by the presence a 52 base pair insert. This changes the reading frame of the derived carboxyl-terminal resulting in a different precursor insulin-like growth factor 1 isoform. This insulin-like growth factor 1 mRNA probably encodes the precursor insulin-like growth factor 1 isoform that is responsible for local muscle growth regulation in response to mechanical stimulation. To confirm that alternative splicing of the insulin-like growth factor 1 gene occurs in muscle in response to physical activity, oligonucleotide primers were made which specifically amplify the cDNAs of two isoforms (insulin-like growth factors 1Ea and Eb) in the human as well as the rabbit. Following altered physical activity for 2 h to 6 days, appreciable levels of insulin-like growth factor 1Eb (in human the Ec) isoform were detected in skeletal muscle by using RT-PCR. In contrast very little if any of this splice variant could be detected in control muscle not subjected to stretch or extra physical activity.

Nitric oxide suppresses apoptosis via interrupting caspase activation and mitochondrial dysfunction in cultured hepatocytes

Nitric oxide (NO) is a potent inhibitor of apoptosis in many cell types, including hepatocytes. We and others have described NO-dependent decreases in caspase activity in cells undergoing apoptosis. However, previous work has not determined whether NO disrupts the proteolytic processing and thus the activation of pro-caspases. Here we report that NO suppresses proteolytic processing and activation of multiple pro-caspases in intact cells, including caspase-3 and caspase-8. We found that both exogenous NO as well as endogenously produced NO via adenoviral inducible NO synthase gene transfer protected hepatocytes from tumor necrosid factor (TNF) alpha plus actinomycin D (TNFalpha/ActD)-induced apoptosis. Affinity labeling with biotin-VAD-fmk of all active caspase species in TNFalpha-mediated apoptosis identified four newly labeled spots (activated caspases) present exclusively in TNFalpha/ActD-treated cells. Both NO and the caspase inhibitor, Ac-DEVD-CHO, prevented the appearance of the four newly labeled spots or active caspases. Immunoanalysis of affinity labeled caspases demonstrated that caspase-3 was the major effector caspase. Western blot analysis also identified the activation of caspase-8 in the TNFalpha/ActD-treated cells, and the activation was suppressed by NO. Furthermore, NO inhibited several other events associated with caspase activation in cells, including release of cytochrome c from mitochondria, decrease in mitochondrial transmembrane potential, and cleavage of poly(ADP-ribose) polymerase in TNFalpha/ActD-treated cells. These findings indicate the involvement of multiple caspases in TNFalpha-mediated apoptosis in hepatocytes and establish the capacity of NO to inhibit not only active caspases but also caspase activation.

Induction of proinflammatory cytokines by a soluble factor of Propionibacterium acnes: implications for chronic inflammatory acne

Although many cytokines have been implicated in the development and persistence of inflammatory immune responses, it is unknown if any of these are important in inflammatory acne. This study investigated the production of the proinflammatory cytokines interleukin-8 (IL-8), IL-1 beta, and tumor necrosis factor alpha (TNF-alpha) by human monocytic cell lines, ThP-1 and U937, and by freshly isolated peripheral blood mononuclear cells from acne patients. Both Propionibacterium acnes and supernatants obtained from 72-h P. acnes cultures could induce significant concentrations of IL-1 beta, TNF-alpha, and IL-8 by both cell lines and by peripheral blood mononuclear cells as determined by enzyme-linked immunosorbent assay. There was no significant difference between acne and non-acne subjects. Endotoxin quantification and addition of polymyxin B to assays indicated no lipopolysaccharide (LPS) contamination. P. acnes supernatant was fractionated into components with molecular weights of < 3,000, < 10,000, and < 30,000 and assayed for the ability to induce IL-8 and TNF production in ThP-1 cells. Nearly 90% of the original activity was found in the < 30,000-molecular-weight fraction, 50% was in the < 10,000-molecular-weight fraction, and only 15% remained in the < 3,000-molecular-weight fraction. The effluent from the < 3,000-molecular-weight fraction contained about 70% activity, indicating that the inducing factor was not retained in the membrane. Incubation of P. acnes supernatant with various concentrations of mutanolysin or lysozyme resulted in a loss of 60% of the original activity. The addition of jimson lectin, which binds peptidoglycan, resulted in a loss of 70% of the activity in a dose-response manner, whereas peanut lectin had little or no effect on the activity. Heating of the P. acnes supernatant to 65 degrees C also had no effect on the activity. Blocking of CD14, a receptor for both LPS and peptidoglycan, reduced cytokine production by > 50%, suggesting that the soluble stimulating factor may be a secreted form of peptidoglycan-polysaccharide.

Functional roles for PECAM-1 (CD31) and VE-cadherin (CD144) in tube assembly and lumen formation in three-dimensional collagen gels

Various in vitro models have been described that emulate one or more of the processes involved in angiogenesis in vivo. In the present study endothelial cells were cultured in three-dimensional type I collagen lattices in the presence of a mixture of basic fibroblast growth factor, vascular endothelial cell growth factor, and phorbol myristate acetate. Under these conditions, the endothelial cells rapidly assemble into an interconnected network of tube-like structures with a high frequency of intercellular canals or lumens. The formation of the networks and lumens was completely blocked by cycloheximide and by actinomycin D. Monoclonal antibodies directed against CD31 or vascular endothelial cadherin (VE-cadherin) inhibited the formation of endothelial tubes. A subtle difference in the morphology of cells treated with anti-CD31 versus anti-VE-cadherin was noted; namely, cells incubated in the presence of CD31 antibodies were rounded or formed attenuated tube-like structures, both of which were characterized by a single, large intra- or intercellular vacuole. In contrast, tube formation by cells incubated in the presence of VE-cadherin antibodies was also impaired and, most notably, demonstrated a reduction in either vacuole formation or vacuole fusion, depending upon the monoclonal antibody used. We suggest that the two endothelial-junction-associated proteins, CD31 and VE-cadherin, play different roles in the process of tube formation. CD31 appears to be required for cell elongation, migration, and/or invasion in the gels as well as for cell-cell association to form the network structures. VE-cadherin also appears to be required for cell-cell association, but additionally appears to play some role in the process of vacuolization or vacuole fusion leading to intercellular lumen formation.

MicroRNA-34 suppresses breast cancer invasion and metastasis by directly targeting Fra-1

MicroRNAs have key roles in tumor metastasis. Here, we describe the regulation and function of miR-34a and miR-34c (miR-34a/c) in breast cancer metastasis. Expression analysis verified that miR-34a/c expression is significantly decreased in metastatic breast cancer cells and human primary breast tumors with lymph node metastases. Overexpression of miR-34a/c could inhibit breast cancer cell migration and invasion in vitro and distal pulmonary metastasis in vivo. Further studies revealed that Fos-related antigen 1 (Fra-1 or Fosl1) is a downstream target of miR-34a/c as miR-34a/c bound directly to the 3'untranslated region of Fra-1, subsequently reducing both the mRNA and protein levels of Fra-1. Silencing of Fra-1 recapitulated the effects of miR-34a/c overexpression, whereas enforced expression of Fra-1 reverses the suppressive effects of miR-34a/c. Moreover, significant downregulation of miR-34a in metastatic breast cancer tissues was found to be inversely correlated with Fra-1 expression. Our results demonstrate that miR-34a/c functions as a metastasis suppressor to regulate breast cancer migration and invasion through targeting Fra-1 oncogene and suggest a therapeutic application of miR-34 in breast cancer.

Body distribution of camptothecin solid lipid nanoparticles after oral administration

PURPOSE

The aim of this study was to investigate the specific changes in body distribution of camptothecin (CA) through incorporation into solid lipid nanoparticles (SLN) by peroral route.

METHODS

Camptothecin loaded solid lipid nanoparticles (CA-SLN) coated with poloxamer 188 were produced by high pressure homogenization. The CA-SLN were characterized by transmission electron microscopy and electrophoretic mobility measurement. In vitro release characteristics of camptothecin from CA-SLN were studied at different pH media. The concentration of camptothecin in organs was determined using reversed-phase high-performance liquid chromatography with a fluorescence detector after oral administration of CA-SLN and a camptothecin control solution (CA-SOL).

RESULTS

Our results showed that CA-SLN had an average diameter 196.8 nm with Zeta potential of -69.3 mV. The encapsulation efficiency of camptothecin was 99.6%, and in vitro drug release was achieved up to a week. There were two peaks in the camptothecin concentration-time curves in plasma and tested organs after oral administration of CA-SLN. The first peak was the result of free drug and the second peak was indicative of gut uptake of CA-SLN after 3 hours. In tested organs, the area under curve (AUC) and mean residence time (MRT) of CA-SLN increased significantly as compared with CA-SOL, and the increase of brain AUC was the highest among all tested organs.

CONCLUSIONS

The results indicate SLN could be a promising sustained release and targeting system for camptothecin or other lipophilic antitumor drugs after oral administration.