The mechanism of uptake of biodegradable microparticles in Caco-2 cells is size dependent

PURPOSE

To study the uptake of biodegradable microparticles in Caco-2 cells.

METHODS

Biodegradable microparticles of polylactic polyglycolic acid co-polymer (PLGA 50:50) of mean diameters 0.1 micron, 1 micron, and 10 microns containing bovine serum albumin as a model protein and 6-coumarin as a fluorescent marker were formulated by a multiple emulsion technique. The Caco-2 cell monolayers were incubated with each diameter microparticles (100 micrograms/ml) for two hours. The microparticle uptake in Caco-2 cells was studied by confocal microscopy and also by quantitating the 6-coumarin content of the microparticles taken up by the cells. The effects of microparticle concentration, and incubation time and temperature on microparticle cell uptake were also studied.

RESULTS

The study demonstrated that the Caco-2 cell microparticle uptake significantly depends upon the microparticle diameter. The 0.1 micron diameter microparticles had 2.5 fold greater uptake on the weight basis than the 1 micron and 6 fold greater than the 10 microns diameter microparticles. Similarly in terms of number the uptake of 0.1 micron diameter microparticles was 2.7 x 10(3) fold greater than the 1 micron and 6.7 x 10(6) greater than the 10 microns diameter microparticles. The efficiency of uptake of 0.1 micron diameter microparticles at 100 micrograms/ml concentration was 41% compared to 15% and 6% for the 1 micron and the 10 microns diameter microparticles, respectively. The Caco-2 cell microparticle (0.1 micron) uptake increased with concentration in the range of 100 micrograms/ml to 500 micrograms/ml which then reached a plateau at higher concentration. The uptake of microparticles increased with incubation time, reaching a steady state at two hours. The uptake was greater at an incubation temperature of 37 degrees C compared to at 4 degrees C.

CONCLUSIONS

The Caco-2 cell microparticle uptake was microparticle diameter, concentration, and incubation time and temperature dependent. The small diameter microparticles (0.1 micron) had significantly greater uptake compared to larger diameter microparticles. The results thus suggest that the mechanism of uptake of microparticles in Caco-2 cell is particle diameter dependent. Caco-2 cells are used as an in vitro model for gastrointestinal uptake, and therefore the results obtained in these studies could be of significant importance in optimizing the microparticle-based oral drug delivery systems.

Influenza A vaccine decreases the incidence of otitis media in 6- to 30-month-old children in day care

OBJECTIVE

To determine if the use of influenza vaccine in children in day care decreases the incidence of otitis media during the influenza season.

DESIGN

Prospective cohort study.

SETTING

Eight day-care centers in North Carolina.

PARTICIPANTS

One hundred eighty-six children aged 6 to 30 months.

INTERVENTION

Half the participants received trivalent subvirion influenza virus vaccine.

MEASUREMENTS

Acute otitis media (AOM) and serous otitis media (SOM) were assessed biweekly from mid-November 1993 to mid-March 1994 by visual and tympanometric examinations performed by "blinded" observers. The winter season was divided into three periods-before, during, and after influenza season--and the number of children with AOM or SOM during each period was determined. Unadjusted and adjusted odds ratios (ORs) were computed, while controlling for race and sex using logistic regression methods.

RESULTS

Influenza vaccine was protective against AOM (OR = 0.69, 95% CI, 0.49-0.98) during the influenza season. Although there may have been some protection against SOM (OR = 0.75, 95% CI, 0.54-1.02) statistical significance was not achieved. Myringotomy tubes were also significantly protective against AOM and SOM during all three time periods, with ORs between 0.34 and 0.52, but the greatest protection was seen during the influenza period.

CONCLUSIONS

Influenza vaccination of 6- to 30-month-old children in day care was associated with a decreased incidence of otitis media during the influenza season. Myringotomy tubes protected against AOM and SOM during all 16 weeks monitored.

Plasma clearance, organ distribution and target cells of interleukin-6/hepatocyte-stimulating factor in the rat

The plasma half-life of recombinant human interleukin-6 (rhIL-6) was determined in rats by measuring the disappearance of the biological activity as well as of the radioactivity of 125I-rhIL-6 from the circulation. The kinetics of clearance were biphasic. It consisted of a rapid initial disappearance corresponding to a half-life of 3 min, and of a second slow one corresponding to a half-life of about 55 min. By cellulose-acetate electrophoresis it was shown that rhIL-6 binds to a plasma protein resulting in a complex migrating in the beta-gamma region; 20 min after intravenous injection, about 80% of the 125I-rhIL-6 that had disappeared from the circulation was found in the liver. 125I-rhIL-6 was exclusively localized on the surface of parenchymal cells suggesting the existence of an interleukin-6 receptor on the hepatocytes.

HT29-MTX/Caco-2 cocultures as an in vitro model for the intestinal epithelium: in vitro-in vivo correlation with permeability data from rats and humans

The diverse secretory and absorptive functions of the intestinal epithelium are conducted by a mixed population of absorptive cells and mucus-producing goblet cells as the major cell types. In order to approach the main characteristics in an in vitro model, a coculture system of absorptive Caco-2 cells and mucus-secreting HT29-MTX cells was developed and the permeability of a range of different drugs was tested. Variable goblet cell frequency can be achieved, preserving a significant barrier to drug transport and maintaining the differentiated features of both cell types. Absorption rates for actively transported drugs are rather underestimated in the cell culture model when compared to in vivo data. However, a good correlation with fraction absorbed in humans was attained separating the range of passively transported drugs into two groups of well-absorbable compounds with Peff > or = 10 x 10(-6) cm/s and drugs that are absorbed 40-70% with Peff = 0.1-1 x 10(-5) cm/s. A permeability of Peff < 0.1 x 10(-5) cm/s is suggested for low absorbable drugs.

Microencapsulation of DNA using poly(DL-lactide-co-glycolide): stability issues and release characteristics

The design of DNA vaccination delivery systems for the targeting of professional antigen presenting cells could be an interesting approach to elicit cytotoxic T-cell responses to fight viral infections and in cancer therapy. Stability studies with linear high and low molecular DNA and supercoiled plasmid DNA were performed in order to check their ability to withstand stress conditions applied during formulation processes. DNA was tested for integrity by the PicoGreen assay and transfectivity was assessed in cell culture transfection experiments. Double-stranded DNA is extremely stable under physiological conditions in vitro but is rapidly degraded under acidic conditions and high shear forces. Thereby, different stress factors resulted in distinct degradation patterns such as fragmentation and strand separation possibly followed by further decomposition of single-stranded DNA. DNA containing PLGA microparticles as a potential delivery system was prepared by spray-drying. Encapsulation efficiency, DNA stability and burst release varied significantly depending on the different parameters explored in this study. The microencapsulation process was altered to achieve maximal stability of encapsulated DNA by reducing exposure to shear forces and by the addition of NaHCO(3) which acts as a buffering agent and furthermore stabilizes dsDNA against mechanical degradation. Stability of DNA is maintained during the burst release phase, but massive degradation occurred during the second release phase possibly due to acidic catalyzed decomposition. In summary, we feel that microencapsulation of DNA vaccines by spray-drying offers manifold possibilities to design suitable delivery systems in terms of optimizing phagocytosis by APCs and maintaining stability of DNA in phagosomes.

Evaluation of particle uptake in human blood monocyte-derived cells in vitro. Does phagocytosis activity of dendritic cells measure up with macrophages?

This work focuses on microparticles as potential antigen delivery systems to target professional antigen-presenting cells. Surface modified polystyrene microparticles were administered to human-derived macrophages (MPhis) and dendritic cells (DCs) in vitro to evaluate the phagocytosis activity of each cell type. To discriminate between internalised particles and those closely attached to the outside of the cells, particle internalisation was verified by confocal laser scanning microscopy. Especially positively charged particles tend to stick to the outer cell membrane and may lead to false positive results when measured by conventional microscopy. In contrast, fluorescence microscopy in combination with an extracellular fluorescence quenching agent (trypan blue) allows the unequivocal assessment of particle uptake for screening purposes. For this assay, the fluorescent label needs to be in direct contact to the quenching agent and cannot be localised inside the particle core. Different types of microparticles varying in size, surface-material and zeta potential resulted in vast differences regarding their uptake by MPhis and DCs as well as the maturation of DCs. Negatively-charged carboxylated and bovine serum albumin-coated particles were phagocytosed by MPhis to a relatively small extent. Interestingly, phagocytosis of these particles was still significantly lower in DCs while positively charged poly-L-lysine (PLL) coated particles induced high phagocytosis activity in both cell types. By comparing our results with literature data, we conclude that phagocytosis activity of DCs and MPhis largely depends on particle size and surface charge and is also influenced by the character of bulk and coating material. PLL can be directed to DCs and MPhis with comparable efficiency and, in addition, induce maturation of DCs.

Hydrophilic poly(DL-lactide-co-glycolide) microspheres for the delivery of DNA to human-derived macrophages and dendritic cells

Biodegradable poly(lactide-co-glycolide) (PLGA) microspheres have a proven track record for drug delivery and are suggested to be ideal carrier systems to target therapeutics into phagocytic cells such as macrophages (MPhis) and dendritic cells (DCs). Microspheres prepared by spray-drying from different PLGA-type polymers were evaluated regarding their effect on phagocytosis, intracellular degradation and viability of human-derived macrophages MPhis and DCs. Even the microspheres prepared from the most hydrophilic polymer RG502H, were efficiently phagocytosed by primary human MPhis and DCs. Interestingly, uptake of PLGA microspheres by DCs as potent immune modulator cells was almost as efficient as uptake by the highly phagocytic MPhis. Phagocytosed microspheres remained inside the cells until decay with none of the microsphere preparations induced significant apoptosis or necrotic cell death. Acidic pH and the phagosomal environment inside the cells enhanced microsphere decay and release of encapsulated material. Degradation of microspheres consisting of the most hydrophilic PLGA polymer RG502H occurred in a reasonable time frame of less than 2 weeks ensuring the release of encapsulated drug during the life span of the cells. To explore important technical and biological aspects of DNA microencapsulation, we have studied DNA loading and in vitro DNA release of microspheres from different PLGA type polymers. Hydrophobicity and molecular weight of the PLGA polymers had profound influence on both the encapsulation efficiency of DNA and its release kinetics in vitro: the hydrophilic polymers showed higher encapsulation efficiency and faster release of intact DNA compared to the hydrophobic ones. These results suggest that microspheres from the PLGA polymer RG502H have improved characteristics for DNA delivery to human MPhis and DCs.

Long-term follow-up of posttransfusion and sporadic chronic hepatitis non-A, non-B and frequency of circulating antibodies to hepatitis C virus (HCV)

The natural course of chronic hepatitis non-A, non-B (HNANB) was documented for 3-20 yr (mean 8 yr) in 86 patients, who attended our special ambulance between 1981 and 1988. Sixty five of the 86 patients (75%) were positive for circulating antibodies against hepatitis C virus (HCV) (anti-HCV). Twenty four patients had chronic posttransfusion (PT)-HNANB (18 anti-HCV-positive; 75%), and 62 patients had sporadic (S)-HNANB (47 anti-HCV-positive; 75%). Twenty nine per cent of patients with chronic PT-HNANB had sustained normalization of aminotransferases after a period up to 5 yr, 55% demonstrated chronic persistent hepatitis (CPH) and 16% progressed to chronic active hepatitis (CAH) with transition to cirrhosis. In the group with chronic S-HNANB, 2% of patients showed remission, 43% had stable CPH and 55% progressed to CAH or cirrhosis. However, development of cirrhotic complications required many years. Transition from CAH to CPH or remission was not observed. The results indicate that 75% of both patients groups with chronic PT- and S-HNANB are infected with the same agent, of which antibodies are detected by the new anti-HCV assay. There was no statistical association between the severity of the disease and the presence of anti-HCV. The different proportions of progressive courses in chronic PT- and S-HNANB might be explained by the patient recruitment.

Transjugular intrahepatic portosystemic stent-shunt (TIPS) in the treatment of Budd-Chiari syndrome

Budd-Chiari syndrome is characterized by splanchnic congestion due to obstruction of the hepatic venous outflow. A variety of treatment modalities have limited applicability due to their invasive nature, complications or low effectivity. The transjugular intrahepatic portosystemic stent-shunt (TIPS) offers a new treatment by creating an intraparenchymal duct between a main branch of the portal vein and hepatic vein i.e. the intrahepatic part of the inferior vena cava. This paper describes the treatment of two patients with fulminant and subacute Budd-Chiari syndrome treated 2 days and 2 months after the onset of clinical symptoms. It demonstrates that TIPS is a feasible treatment of Budd-Chiari syndrome that restores splanchnic blood flow, reduces collateral circulation and ascites and provides sufficient time to allow for elective liver transplantation, if indicated. Further studies are required to evaluate the effect of TIPS on liver function and survival.

In vivo inhibition of duck hepatitis B virus replication and gene expression by phosphorothioate modified antisense oligodeoxynucleotides

Antisense oligodeoxynucleotide strategies have been employed in a variety of eukaryotic systems both to understand normal gene function and to block gene expression. Pharmacologically, 'code blockers' are ideal agents for antitumour and antimicrobial treatments because of their specific mode of action. Here we report the inhibition of duck hepatitis B virus (DHBV) by antisense oligodeoxynucleotides in primary duck hepatocyte cultures in vitro as well as in DHBV-infected Pekin ducks in vivo. The most effective antisense oligodeoxynucleotide was directed against the 5' region of the pre-S gene and resulted in a complete inhibition of viral replication and gene expression in vitro and in vivo. These results demonstrate the application of antisense oligodeoxynucleotides in vivo and exemplify their potential as human antiviral therapeutics.

Synthesis of bioadhesive poly(acrylic acid) nano- and microparticles using an inverse emulsion polymerization method for the entrapment of hydrophilic drug candidates

Bioadhesive latices of water-swollen poly(acrylic acid) nano-and microparticles were synthesized using an inverse (W/O) emulsion polymerization method. They are stabilized by a co-emulsifier system consisting of SpanTM 80 and TweenTM 80 dispersed in aliphatic hydrocarbons. The initial polymerization medium contains emulsion droplets and inverse micelles which solubilize a part of the monomer solution. The polymerization is initiated by free radicals, and particle dispersions with a narrow size distribution are obtained. The particle size is dependent on the type of radical initiator used. With water-soluble initiators, for example ammonium persulfate, microparticles were obtained in the size range of 1 to 10 micrometer indicating that these microparticles originate from the emulsion droplets since the droplet sizes of the W/O emulsion show similar distribution. When lipophilic radical initiators, such as azobis-isobutyronitrile, are used, almost exclusively nanoparticles are generated with diameters in the range of 80 to 150 nm, due to the limited solubility of oligomeric poly(acrylic acid) chains in the lipophilic continuous phase. These poly(acrylic acid) micro- and nanoparticles yielded excellent bioadhesive properties in an in-vitro assay and may, therefore, be suitable for the encapsulation of peptides and other hydrophilic drugs.

Hepatitis B virus infection of tupaia hepatocytes in vitro and in vivo

For the systematic analysis of various clinical and molecular aspects of hepatitis B virus (HBV) infection, an experimental small animal system of HBV infection would be a great advance. The susceptibility to HBV infection, therefore, of hepatocytes from the tree shrew species tupaia belangeri was studied in vitro and in vivo. Primary hepatocytes isolated from livers of tupaias can be reproducibly infected with HBV. In vitro infection results in viral DNA and RNA synthesis in hepatocytes and secretion hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) into culture medium. Tupaias can also be infected with HBV in vivo, resulting in viral DNA replication and gene expression in tupaia livers. Similar to acute, self-limited hepatitis B in humans HBsAg is rapidly cleared from serum, followed by seroconversion to anti-HBe and anti-HBs. These data clearly tht HBV is infectious to tupaia hepatocytes in vitro and transiently in vivo. Tupaias, therefore, may become a useful model for the experimental analysis of various molecular and clinical aspects of HBV infection, including the significance of HBV quasispecies, the steps involved in hepatocarcinogenesis as well as the evaluation of various antiviral strategies.

HIV-1 sensitivity to zidovudine and clinical outcome in children

In adults with the acquired immunodeficiency syndrome, long-term monotherapy with zidovudine selects for human immunodeficiency virus type 1 (HIV-1) strains with substantially reduced in-vitro susceptibility to the drug. We have assessed the relation between in-vitro resistance to zidovudine and clinical outcome in children, in whom disease progression is more rapid than in adults. We studied 23 children with symptoms of HIV-1 disease during extended monotherapy with zidovudine. An in-vitro assay was used to determine the concentration of zidovudine required to inhibit by 50% the replication of viral isolates (IC50) obtained after 9 to 39 months of treatment. Viral stocks of high enough titre to yield reproducible results were obtained from 19 of the children. During the following 6 months of therapy, 9 children were stable, 7 deteriorated, and 3 died. There was a highly significant relation between decreased zidovudine susceptibility and poor clinical outcome (p less than 0.001) but no relation between IC50 and age at start of therapy or length of time on treatment. Age-adjusted CD4 lymphocyte counts were lower at the start of treatment (p = 0.02) and at the time of sampling (p = 0.01) in children whose viral isolates had an increased zidovudine IC50. Initial serum p24 antigen levels were not predictive of subsequent emergence of resistant virus, but at the time of sampling for viral sensitivity higher p24 antigen levels were associated with raised IC50 (p = 0.004). The findings suggest that most children who become unresponsive to monotherapy with zidovudine, as judged by clinical criteria, will have changes in in-vitro sensitivity to the drug. In these children, an alternative antiretroviral therapy should be considered.

Surface modification of PLGA microspheres

Microspheres made of poly(lactic-co-glycolic acid) (PLGA) are biocompatible and biodegradable, rendering them a promising tool in the context of drug delivery. However, nonspecific adsorption of plasma proteins on PLGA micro- and nanospheres is a main limitation of drug targeting. Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG), physisorbed on flat metal oxide surfaces, has previously been shown to suppress protein adsorption drastically. The goal of our work was to characterize the efficiency of the protein repellent character of PLL-g-PEG on PLGA microspheres and to show the feasibility of introducing functional groups on the PLGA microspheres via functionalized PLL-g-PEG. To quantify the adsorbed amount of protein, a semiquantitative method that uses confocal laser scanning microscopy (CLSM) was applied. The first part of the experiment confirms the feasibility of introducing specific functional groups on PLL-g-PEG-coated PLGA microspheres. In the second part of the experiment, PLL-g-PEG-coated PLGA microspheres show a drastic decrease of adsorbed proteins by two orders of magnitude in comparison to uncoated PLGA microspheres. Low protein-binding, functionalizable microspheres provide a fundamental basis for the design of drug delivery and biosensor systems.

Effects of the NO/soluble guanylate cyclase/cGMP system on the functions of human platelets

Platelets are circulating sentinels of vascular integrity and are activated, inhibited, or modulated by multiple hormones, vasoactive substances or drugs. Endothelium- or drug-derived NO strongly inhibits platelet activation via activation of the soluble guanylate cyclase (sGC) and cGMP elevation, often in synergy with cAMP-elevation by prostacyclin. However, the molecular mechanisms and diversity of cGMP effects in platelets are poorly understood and sometimes controversial. Recently, we established the quantitative human platelet proteome, the iloprost/prostacyclin/cAMP/protein kinase A (PKA)-regulated phosphoproteome, and the interactions of the ADP- and iloprost/prostacyclin-affected phosphoproteome. We also showed that the sGC stimulator riociguat is in vitro a highly specific inhibitor, via cGMP, of various functions of human platelets. Here, we review the regulatory role of the cGMP/protein kinase G (PKG) system in human platelet function, and our current approaches to establish and analyze the phosphoproteome after selective stimulation of the sGC/cGMP pathway by NO donors and riociguat. Present data indicate an extensive and diverse NO/riociguat/cGMP phosphoproteome, which has to be compared with the cAMP phosphoproteome. In particular, sGC/cGMP-regulated phosphorylation of many membrane proteins, G-proteins and their regulators, signaling molecules, protein kinases, and proteins involved in Ca²⁺ regulation, suggests that the sGC/cGMP system targets multiple signaling networks rather than a limited number of PKG substrate proteins.

Liver-directed gene transfer: a linear polyethlenimine derivative mediates highly efficient DNA delivery to primary hepatocytes in vitro and in vivo

Efficient DNA delivery is a prerequisite for the successful implementation of molecular antiviral strategies against chronic viral hepatitis and gene therapy in general. The cationic polymer polyethylenimine (PEI) has recently been explored as a gene transfer vector in various cell types in vitro and in vivo. In this study, we evaluated a linear PEI derivative (lPEI) as a vector for gene and oligodeoxynucleotide transfer into hepatocytes in vitro and in vivo. A simple protocol was developed that allowed transfection of up to 50% of primary hepatocytes in vitro. In addition, fluorescent oligodeoxynucleotides were efficiently delivered to the liver in vivo after intravenous injection into Pekin ducks. Thus, lPEI mediates highly efficient gene and oligodeoxynucleotide transfer into primary hepatocytes and is potentially useful for DNA delivery in vivo.

Synthetic quantitative array technology identifies the Ubp3-Bre5 deubiquitinase complex as a negative regulator of mitophagy

Mitophagy is crucial to ensuring mitochondrial quality control. However, the molecular mechanism and regulation of mitophagy are still not fully understood. Here, we developed a quantitative methodology termed synthetic quantitative array (SQA) technology, which allowed us to perform a genome-wide screen for modulators of rapamycin-induced mitophagy in S. cerevisiae. SQA technology can be easily employed for other enzyme-based reporter systems and widely applied in yeast research. We identified 86 positive and 10 negative regulators of mitophagy. Moreover, SQA-based analysis of non-selective autophagy revealed that 63 of these regulators are specific for mitophagy and 33 regulate autophagy in general. The Ubp3-Bre5 deubiquitination complex was found to inhibit mitophagy but, conversely, to promote other types of autophagy, including ribophagy. This complex translocates dynamically to mitochondria upon induction of mitophagy. These findings point to a role of ubiquitination in mitophagy in yeast and suggest a reciprocal regulation of distinct autophagy pathways.

Acute kidney injury associated with endurance events-is it a cause for concern? A systematic review

INTRODUCTION

A growing body of evidence suggests even small rises in serum creatinine (SCr) are of considerable clinical relevance. Given that participants in endurance events are exposed to potential (repeated) renal insults, a systematic review was undertaken to collate current evidence for acute kidney injury (AKI), complicating such events.

METHODS

A systematic review of studies and case reports meeting inclusion criteria on Medline and EMBASE (inception to October 2015). Included: studies with markers of renal function before and after endurance or ultraendurance events; case reports of severe AKI. Two reviewers assessed risk of bias using the Newcastle-Ottawa scale.

RESULTS

Eleven case report publications (n=27 individuals) of severe AKI, were retrieved, with risk factors including systemic illness or nephrotoxic medications usually identified. From 30 studies of endurance and ultraendurance events, mean rise in SCr was 29 (±12.3) µmol/L after marathon or ultramarathon (17 studies, n=568 participants) events. Where follow-up tests were conducted, SCr returned to baseline within 48 hours. Rises in biomarkers suggest potential parenchymal insult, rather than simply muscle breakdown. However, evidence of long-term deleterious effects is lacking.

CONCLUSIONS

Raised levels of SCr are reported immediately after endurance events. It is not clear whether this is either clinically significant, or if repeated participation predisposes to long-term sequelae. The aetiology of severe exercise-associated AKI is usually multifactorial, with risk factors generally identified in the rare cases reported. On-site biochemistry, urine analysis and biomarkers of AKI may help identify collapsed runners who are at significant short-term risk and allow suitable follow-up.

Taking the stock of granule cargo: Platelet releasate proteomics

Human platelets are key players in a multitude of physiological and pathological processes. Upon activation they release cargo from different types of granules as well as microparticles in an apparently well-regulated and orchestrated manner. The resulting specific platelet releasates create microenvironments of biologically active compounds and proteins during platelet aggregation and thrombus formation, allowing efficient delivery of growth factors and immune modulators to their sites of effect and enhancing the coagulative response in a positive feedback loop. Thus, platelet releasates play a central role in the regulation of platelet homeostasis and heterotypic cell interaction. Additionally, it recently emerged that both the qualitative and quantitative composition of the releasate as well as release dynamics may be stimulus dependent and therefore more complex than expected. Mass spectrometry-based proteomics is an important asset for studying platelet releasates in vitro, as it allows not only (i) identifying released proteins, but moreover (ii) determining their quantities and the dynamics of release as well as (iii) differentially comparing releasates across a variety of conditions. Though owing to the high sensitivity and comprehensiveness of modern proteomic techniques, a thorough experimental design and a standardized and robust sample preparation are essential to obtain highly confident and reliable insights into platelet biology and pathology. Here, we review releasate proteome studies and crucial sample preparation strategies to summarize possible achievements of state-of-the-art technologies and furthermore discuss potential pitfalls and limitations. We provide a future perspective of platelet releasate proteomics including targeted analyses, post-translational modifications and multi-omics approaches that should be adopted by platelet releasate researchers due to their tremendous depth and comprehensiveness.

Insights into brain development from neurogenetic syndromes: evidence from fragile X syndrome, Williams syndrome, Turner syndrome and velocardiofacial syndrome

Over the past few decades, behavioral, neuroimaging and molecular studies of neurogenetic conditions, such as Williams, fragile X, Turner and velocardiofacial (22q11.2 deletion) syndromes, have led to important insights regarding brain development. These investigations allow researchers to examine "experiments of nature" in which the deletion or alteration of one gene or a contiguous set of genes can be linked to aberrant brain structure or function. Converging evidence across multiple imaging modalities has now begun to highlight the abnormal neural circuitry characterizing many individual neurogenetic syndromes. Furthermore, there has been renewed interest in combining analyses across neurogenetic conditions in order to search for common organizing principles in development. In this review, we highlight converging evidence across syndromes from multiple neuroimaging modalities, with a particular emphasis on functional imaging. In addition, we discuss the commonalities and differences pertaining to selective deficits in visuospatial processing that occur across four neurogenetic syndromes. We suggest avenues for future exploration, with the goal of achieving a deeper understanding of the neural abnormalities in these affected populations.

Penicillin-induced coagulation disorder

A coagulation disorder was seen after penicillin-G administration (10 million units/day) in uraemic patients and after high-dose penicillin G (40 million units/day) in patients with a normal glomerular filtration-rate (5 patients after cardiac surgery). This disorder was characterised by: prolongation of bleeding-time, appearing immediately after penicillin-G administration and persisting until 4 days after withdrawal of therapy; disturbance of collagen-induced and ristocetin-induced platelet aggregation; increase of antithrombin-III activity; and inhibition of factor-xa activity. The inhibition of factor-xa activity corresponded to that seen after low-dose-heparin prophylaxis. The clinically latent coagulation disorder, when super-imposed upon pre-existing coagulation abnormalities (uraemia, treatment with anti-coagulants) may cause severe bleeding, as observed in 1 patient with acute renal failure on haemodialysis.

Transepithelial transport properties of peptidomimetic thrombin inhibitors in monolayers of a human intestinal cell line (Caco-2) and their correlation to in vivo data

Peptidomimetic thrombin inhibitors (TI), derived from L-Asp-D-Phe were examined in confluent monolayers of a human colon carcinoma cell line (Caco-2) to elucidate their transepithelial transport properties. Effect availabilities, based on activated partial thromboplastin time (aPTT) measurements in rats, after peroral administration of five TI correlated reasonably well with permeability coefficients obtained from in vitro transport studies in Caco-2 monolayers, whereas physicochemical properties, such as molecular mass, solubilities, pKa and octanol-buffer partition coefficients failed to yield meaningful relationships. Substitution of the beta-carboxylic group of L-Asp leads to analogues which are mainly transported by passive diffusion, while an unsubstituted carboxylic group favours carrier-mediated active transport. The effects of concentration, temperature, competitive inhibitors and direction dependence on in vitro transport were investigated. The results obtained are compatible with a saturable carrier-mediated transport, operating parallel to a passive paracellular route. The Michaelis-Menten parameters for the active transport component (Km = 1.67 mM, Vmax = 26.5 pmol min-1 mg protein-1) indicate an involvement of the intestinal di/tripeptide transport system for one of the TI. The Caco-2 transport model may be helpful for the design of perorally active peptidomimetics.

Role of integrin expression in adenovirus-mediated gene delivery to the intestinal epithelium

Adenoviral vectors are being developed for oral delivery of therapeutic genes to the intestine. Initial studies in the rat using mucolytics and direct application of adenovirus encoded with the interleukin-1 receptor antagonist gene to the jejunum produced limited gene expression. The goal of this study was to determine the role of integrins in adenovirus-mediated gene delivery to the intestinal epithelium. Integrins are involved in cellular differentiation and tight junction formation and mediate adenoviral internalization. Results from Caco-2 and IEC-18 cells suggest that, as enterocytes differentiate, cell-surface integrin expression decreases. Pretreatment of Caco-2 cells with RGD peptides reduced adenoviral transduction efficiency by 80% in undifferentiated cells and 20% in differentiated cells. Both differentiated and undifferentiated IEC-18 cells showed a 70% drop in transduction when pretreated with the peptide. Infection inhibition studies with monoclonal antibodies further suggest that alpha(v)beta3 and alpha6beta1 integrins play significant roles in adenoviral internalization in the intestine. Expression of integrins in cell culture models of the intestine correlated with in vivo expression in intestinal segments. These results indicate that the ileum is a prime target for efficient adenovirus-mediated gene transfer in the rat. To enhance transduction in differentiated enterocytes (probable targets for oral gene delivery), Caco-2 cells were treated with interleukin-1beta (a cytokine known to increase integrin expression) prior to administration of the virus. Transduction efficiency increased four-fold.