Experimental microdissection enables functional harmonisation of pancreatic cancer subtypes

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDA) has among the highest stromal fractions of any cancer and this has complicated attempts at expression-based molecular classification. The goal of this work is to profile purified samples of human PDA epithelium and stroma and examine their respective contributions to gene expression in bulk PDA samples.

DESIGN

We used laser capture microdissection (LCM) and RNA sequencing to profile the expression of 60 matched pairs of human PDA malignant epithelium and stroma samples. We then used these data to train a computational model that allowed us to infer tissue composition and generate virtual compartment-specific expression profiles from bulk gene expression cohorts.

RESULTS

Our analysis found significant variation in the tissue composition of pancreatic tumours from different public cohorts. Computational removal of stromal gene expression resulted in the reclassification of some tumours, reconciling functional differences between different cohorts. Furthermore, we established a novel classification signature from a total of 110 purified human PDA stroma samples, finding two groups that differ in the extracellular matrix-associated and immune-associated processes. Lastly, a systematic evaluation of cross-compartment subtypes spanning four patient cohorts indicated partial dependence between epithelial and stromal molecular subtypes.

CONCLUSION

Our findings add clarity to the nature and number of molecular subtypes in PDA, expand our understanding of global transcriptional programmes in the stroma and harmonise the results of molecular subtyping efforts across independent cohorts.

Kinetic modeling of [11C]raclopride: combined PET-microdialysis studies

The in vivo binding of D2 receptor ligands can be affected by agents that alter the concentration of endogenous dopamine. To define a more explicit relation between dopamine and D2 receptor binding, the conventional compartment model for reversible ligands has been extended to account for a time-varying dopamine pulse. This model was tested with [11C]raclopride positron emission tomography and dopamine microdialysis data that were acquired simultaneously in rhesus monkeys. The microdialysis data were incorporated into the model assuming a proportional relation to synaptic dopamine. Positron emission tomography studies used a bolus-plus-infusion tracer delivery with amphetamine given at 40 minutes to induce dopamine release. The extended model described the entire striatal time-activity curve, including the decrease in radioactivity concentration after an amphetamine-induced dopamine pulse. Based on these results, simulation studies were performed using the extended model. The simulation studies showed that the percent decrease in specific binding after amphetamine measured with the bolus-plus-infusion protocol correlates well with the integral of the postamphetamine dopamine pulse. This suggests that changes in specific binding observed in studies in humans can be interpreted as being linearly proportional to the integral of the amphetamine-induced dopamine pulse.

A prediction model for type 2 diabetes risk among Chinese people

AIMS/HYPOTHESIS

A range of prediction rules for the onset of type 2 diabetes have been proposed. However, most studies have been conducted in white groups and it is not clear whether these models apply to Asian populations. The purpose of this study was to construct a simple points model for predicting incident diabetes among Chinese people.

METHODS

We estimated the 10 year risk of diabetes in a cohort study of middle-aged and elderly participants who were free from diabetes at baseline. Cox regression coefficients were used to construct the simple points model and the discriminatory ability of the resulting prediction rule was determined using AUC and net reclassification improvement and integrated discrimination improvement statistics. Fivefold random splitting was used to test the internal validity and obtain bootstrap estimates of the AUC.

RESULTS

Of the 2,960 participants without diabetes at the baseline examination, 548 developed type 2 diabetes during a median 10 year follow-up period. Age (four points), elevated fasting glucose (11 points), body mass index (eight points), triacylglycerol (five points), white blood cell count (four points) and a higher HDL-cholesterol (negative four points) were found to strongly predict diabetes incidence in a multivariate model. The estimated AUC for the model was 0.702 (95% CI 0.676-0.727). This model performed better than existing prediction models developed in other populations, including the Prospective Cardiovascular Münster, Cambridge, San Antonia and Framingham models for diabetes risk.

CONCLUSIONS/INTERPRETATION

We have constructed a model for predicting the 10 year incidence of diabetes in Chinese people that could be useful for identifying individuals at high risk of diabetes in the Chinese population.

Hint1 is a haplo-insufficient tumor suppressor in mice

The HINT1 protein, a member of the histidine triad (HIT) family, is highly conserved in diverse species and ubiquitously expressed in mammalian tissues. However, its precise function in mammalian cells is not known. As a result of its structural similarity to the tumor-suppressor protein FHIT, we used homozygous-deleted Hint1 mice to study its role in tumorigenesis. We discovered that after 2 to 3 years of age the spontaneous tumor incidence in Hint1 -/- mice was significantly greater than that in wild-type Hint1 +/+ mice (P < 0.05). Using a well-established mouse model of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinogenesis we found a marked and significant (P < 0.05) increase in the incidence of mammary and ovarian tumors in both, Hint1 -/- and +/- mice versus +/+ mice. The Hint1 -/- and +/- mice had similar tumor incidence and similar tumor histologies. Therefore, deletion of Hint1 in mice enhances both spontaneous tumor development and susceptibility to tumor induction by DMBA. In addition, since the Hint1 +/- tumors retained expression of the unmutated wild-type allele, Hint1 is haplo-insufficient with respect to tumor suppression in this model system.

Chin-Shan Community Cardiovascular Cohort in Taiwan-baseline data and five-year follow-up morbidity and mortality

A cohort consisting of 3602 residents (82.8% of the target population) aged 35 years and older was established in 1990 in the Chin-Shan Community, a suburb 20 miles outside of metropolitan Taipei, Taiwan. The long-term objective was to investigate the prospective impact on cardiovascular health in a society undergoing transition from a developing to a developed nation. This article presents the study design, selected baseline risk factors of cardiovascular diseases (CVD), and CVD events at the 5-year follow-up evaluation with an emphasis on sociodemographic differences. The multivariate logistic regression analyses revealed that white-collar individuals were more likely than blue-collar workers to have dyslipidemia including high-density lipoprotein cholesterol (HDL-C) levels <35 mg/dl [odds ratio (OR) = 1.7, 95% confidence interval (CI) = 1.2-2.4] and low-density lipoprotein cholesterol (LDL-C) levels >/=160 mg/dl (OR = 1.3, 95% CI = 1.0-1.7). However, they were at slightly lower risk for stroke and CVD/sudden death, and at moderately higher risk for coronary artery disease and diabetes, although both these trends were not significant. Men were more likely than women to have HDL-C levels <35 mg/dl (OR = 1.8, 95% CI = 1.4-2.2), but they were less likely to have LDL-C levels >/=160 mg/dl (OR = 0.7, 95% CI = 0.6-0.8). The risk of CVD/sudden death was higher for men than for women during the follow-up period (OR = 1.9, 95% CI = 1.3-2.9). This could be due to risk factors such as a much higher prevalence of tobacco (61.9% vs. 4.5%) and alcohol (43.7% vs. 6.4%) use in men. In conclusion, individuals of higher socioeconomic status have a higher prevalence of dyslipidemia but slightly lower 5-year incidence of CVD events.

Simultaneous synthesis and functionalization of water-soluble up-conversion nanoparticles for in-vitro cell and nude mouse imaging

Water-solubility and biocompatibility are prerequisites for rare-earth up-converting nanophosphors applied to biological imaging. In this work, we have developed a facile and one-step synthesis technique, through which water-soluble NaYF(4): Yb(3+), Er(3+) nanoparticles (NPs) with functional groups including 3-mercaptopropionic acid, 6-aminocaproic acid and poly(ethylene glycol)methyl ether on their surface can be directly prepared without any further surface treatment. Some inorganic salts will be selected as starting materials, water and some low toxic organic agents have been used as reaction media, which differs from earlier works. Structural and up-converting fluorescence are characterized by a variety of techniques. Cell uptake and in-vitro imaging of the as-synthesized NPs have been investigated using a multiphoton con-focal laser scanning microscope with a near-infrared excitation source. Internalization of the bare and functionalized NPs in human lung carcinoma A549 and human cervical carcinoma HeLa cells are studied at a nanoparticle loading of 10 µg mL(-1) over an exposure period from 30 min to 24 h. The cytotoxicity of modified NPs in HeLa cells is found to be low. In addition, the feasibility of the NPs in animal imaging has been demonstrated by subcutaneously injecting these NPs into nude mouse. The results indicated that our directly synthesized NPs coated with various functional groups are promising as bio-imaging agents due to their easy uptake, long lasting, low cytotoxicity, emissive in various human carcinoma cell lines and small animals through up-conversion with near-infrared excitation.

DNA binding properties of two Arabidopsis MADS domain proteins: binding consensus and dimer formation

MADS domain proteins are members of a highly conserved family found in all eukaryotes. Genetic studies clearly indicate that many plant MADS domain proteins have different regulatory functions in flower development, yet they share a highly conserved DNA binding domain and can bind to very similar sequences. How, then, can these MADS box genes confer their specific functions? Here, we describe results from DNA binding studies of AGL1 and AGL2 (for AGAMOUS-like), two Arabidopsis MADS domain proteins that are preferentially expressed in flowers. We demonstrate that both proteins are sequence-specific DNA binding proteins and show that each binding consensus has distinct features, suggestion a mechanism for specificity. In addition, we show that the proteins with more similar amino acid sequences have more similar binding sequences. We also found that AGL2 binds to DNA in vitro as a dimer and determined the region of AGL2 that is sufficient for DNA binding and dimerization. Finally, we show that several plant MADS domain proteins can bind to DNA either as homodimers or as heterodimers, suggesting that the number of different regulators could be much greater than the number of MADS box genes.

No high Tibetan Plateau until the Neogene

The Late Paleogene surface height and paleoenvironment for the core area of the Qinghai-Tibetan Plateau (QTP) remain critically unresolved. Here, we report the discovery of the youngest well-preserved fossil palm leaves from Tibet. They were recovered from the Late Paleogene (Chattian), ca. 25.5 ± 0.5 million years, paleolake sediments within the Lunpola Basin (32.033°N, 89.767°E), central QTP at a present elevation of 4655 m. The anatomy of palms renders them intrinsically susceptible to freezing, imposing upper bounds on their latitudinal and altitudinal distribution. Combined with model-determined paleoterrestrial lapse rates, this shows that a high plateau cannot have existed in the core of Tibet in the Paleogene. Instead, a deep paleovalley, whose floor was <2.3 km above mean sea level bounded by (>4 km) high mountain systems, formed a topographically highly varied landscape. This finding challenges prevailing views on tectonic processes, monsoon dynamics, and the evolution of Asian biodiversity.

Vector-host interactions governing epidemiology of West Nile virus in Southern California

Southern California remains an important focus of West Nile virus (WNV) activity, with persistently elevated incidence after invasion by the virus in 2003 and subsequent amplification to epidemic levels in 2004. Eco-epidemiological studies of vectors-hosts-pathogen interactions are of paramount importance for better understanding of the transmission dynamics of WNV and other emerging mosquito-borne arboviruses. We investigated vector-host interactions and host-feeding patterns of 531 blood-engorged mosquitoes in four competent mosquito vectors by using a polymerase chain reaction (PCR) method targeting mitochondrial DNA to identify vertebrate hosts of blood-fed mosquitoes. Diagnostic testing by cell culture, real-time reverse transcriptase-PCR, and immunoassays were used to examine WNV infection in blood-fed mosquitoes, mosquito pools, dead birds, and mammals. Prevalence of WNV antibodies among wild birds was estimated by using a blocking enzyme-linked immunosorbent assay. Analyses of engorged Culex quinquefasciatus revealed that this mosquito species acquired 88.4% of the blood meals from avian and 11.6% from mammalian hosts, including humans. Similarly, Culex tarsalis fed 82% on birds and 18% on mammals. Culex erythrothorax fed on both birds (59%) and mammals (41%). In contrast, Culex stigmatosoma acquired all blood meals from avian hosts. House finches and a few other mostly passeriform birds served as the main hosts for the blood-seeking mosquitoes. Evidence of WNV infection was detected in mosquito pools, wild birds, dead birds, and mammals, including human fatalities during the study period. Our results emphasize the important role of house finches and several other passeriform birds in the maintenance and amplification of WNV in southern California, with Cx. quinquefasciatus acting as both the principal enzootic and "bridge vector" responsible for the spillover of WNV to humans. Other mosquito species, such as Cx. tarsalis and Cx. stigmatosoma, are important but less widely distributed, and also contribute to spatial and temporal transmission of WNV in southern California.

Expression of biotransformation enzymes in human fetal olfactory mucosa: potential roles in developmental toxicity

High levels of cytochrome P450 are present in the olfactory mucosa (OM) in mammalian animals and contribute to the known tissue-selective toxicity of numerous chemical compounds. Olfactory toxicity in the perinatal period may have a greater impact on behavior, growth, and development than in adults. To establish a molecular basis for determining the risk of developmental toxicity in OM, the expression of several cytochrome P450 enzymes, as well as NADPH-cytochrome P450 reductase and microsomal epoxide hydrolase, was examined in hepatic and nasal microsomes prepared from human fetal tissues at gestational day 91-125. The relative microsomal concentrations of these biotransformation enzymes were determined on immunoblots. Expression of CYP2A, CYP2J2, the reductase, and epoxide hydrolase was detected in both OM and liver. The microsomal levels of these enzymes were generally lower in OM than in liver of the same fetuses, except for the CYP2A-related proteins, which were expressed in OM at much higher levels. OM expression of CYP2A6, CYP2A13, CYP2B6, and CYP2J2 mRNAs was detected using RNA-PCR. These results document, for the first time, prenatal expression of xenobiotic-bioactivating cytochrome P450 enzymes in human OM and suggest that the human fetal OM may be a preferred target tissue for the toxicity of maternally derived chemical compounds that are activated by the CYP2A enzymes.

Posttraumatic empyema. Risk factor analysis

BACKGROUND

Empyema remains a distressing complication after thoracic injury.

OBJECTIVE

To identify high-risk factors associated with the development of empyema.

DESIGN

Retrospective cohort review.

SETTING

University hospital, level I trauma center.

PATIENTS

Trauma patients who required tube thoracostomy (TT) between January 1, 1991, and November 31, 1993 (n = 584).

METHODS

Data (demographic characteristics, injuries, chest x-ray film reports, and setting of TT) were assessed using a stepwise logistic regression analysis to identify risk factors associated with the development of post-traumatic empyema.

RESULTS

Empyema that required decortication developed in 25 patients (4%). Factors predictive of development of empyema were retained hemothorax (odds ratio, 12.5; 95% confidence interval, 0.96-163), pulmonary contusion (odds ratio, 6.3; 95% confidence interval, 1.53-25.8), and multiple chest tube placement (odds ratio, 2.5; 95% confidence interval, 1.91-3.28); factors not predictive of empyema were severity of injury, mechanism of injury, setting in which TT was performed, number of days chest tubes were in place, and antibiotic drugs at the time of TT.

CONCLUSIONS

The extent of pulmonary injury (pulmonary contusion) is an important predictor of empyema development. Previously implicated factors such as setting in which a TT was performed and mechanism of injury did not correlate with the development of posttraumatic empyema. Based on the results of our study, we recommend early drainage of the pleural space with video-assisted thoracoscopic techniques in patients at risk of empyema, which may spare them the morbidity of a thoracotomy.

Mislocalisation of hephaestin, a multicopper ferroxidase involved in basolateral intestinal iron transport, in the sex linked anaemia mouse

BACKGROUND

Hephaestin is a multicopper ferroxidase required for basolateral transport of iron from enterocytes. Sex linked anaemia (sla) mice have a defect in the release of iron from intestinal enterocytes into the circulation due to an interstitial deletion in the hephaestin gene (heph).

RESULTS

We have demonstrated that hephaestin is primarily localised to a supranuclear compartment in both intestinal enterocytes and in cultured cells. In normal intestinal enterocytes, hephaestin was also present on the basolateral surface. In sla mice, hephaestin was present only in the supranuclear compartment. In contrast, the iron permease Ireg1 localised to the basolateral membrane in both control and sla mice.

CONCLUSION

We suggest that mislocalisation of hephaestin likely contributes to the functional defect in sla intestinal epithelium.

Interferon-alpha 2b enhances barrier function of bovine retinal microvascular endothelium in vitro

Increased permeability of the vascular endothelium is a critical part of pathological processes such as inflammation and wound healing. While several cytokines have been shown to increase endothelial permeability, none has been shown to reduce it. We studied the effect of interferon-alpha 2b on the barrier function of bovine retinal capillary endothelial cells in vitro and found that it increased the electrical resistance of the monolayers (treated cells 211 +/- 6 ohm.cm2, untreated 109 +/- 14 ohm.cm2), decreased their permeability to inulin (Pc inulin of untreated cells 0.73 +/- 0.21 x 10(-6) cm/sec, treated 0.31 +/- 0.23 x 10(-6) cm/sec, P = 0.015), and enhanced their morphological differentiation. Interferon-gamma had no effect. No effect of interferon-alpha treatment on the permeability of bovine aortic endothelial cells was found. We conclude that interferon-alpha 2b can enhance the barrier function of retinal microvascular endothelium in vitro. This is consistent with the hypothesis that interferon-alpha is an effector of a mechanism which actively promotes tissue homeostasis and suggests that it might have therapeutic potential in diseases characterized by leakage of the vascular endothelium.

Novel PRRT2 mutations in paroxysmal dyskinesia patients with variant inheritance and phenotypes

Paroxysmal dyskinesias (PDs) are a group of episodic movement disorders with marked variability in clinical manifestation and potential association with epilepsy. PRRT2 has been identified as a causative gene for PDs, but the phenotypes and inheritance patterns of PRRT2 mutations need further clarification. In this study, 10 familial and 21 sporadic cases with PDs and PDs-related phenotypes were collected. Genomic DNA was screened for PRRT2 mutations by direct sequencing. Seven PRRT2 mutations were identified in nine (90.0%) familial cases and in six (28.6%) sporadic cases. Five mutations are novel: two missense mutations (c.647C>G/p.Pro216Arg and c.872C>T/p.Ala291Val) and three truncating mutations (c.117delA/p.Val41TyrfsX49, c.510dupT/p.Leu171SerfsX3 and c.579dupA/p.Glu194ArgfsX6). Autosomal dominant inheritance with incomplete penetrance was observed in most of the familial cases. In the sporadic cases, inheritance was heterogeneous including recessive inheritance with compound heterozygous mutations, inherited mutations with incomplete parental penetrance and de novo mutation. Variant phenotypes associated with PRRT2 mutations, found in 36.0% of the affected cases, included febrile convulsions, epilepsy, infantile non-convulsive seizures (INCS) and nocturnal convulsions (NC). All patients with INCS or NC, not reported previously, displayed abnormalities on electroencephalogram (EEG). No EEG abnormalities were recorded in patients with classical infantile convulsions and paroxysmal choreoathetosis (ICCA)/paroxysmal kinesigenic dyskinesia (PKD). Our study further confirms that PRRT2 mutations are the most common cause of familial PDs, displaying both dominant and recessive inheritance. Epilepsy may occasionally occur in ICCA/PKD patients with PRRT2 mutations. Variant phenotypes INCS or NC differ from classical ICCA/PKD clinically and electroencephalographically. They have some similarities with, but not identical to epilepsy, possibly represent an overlap between ICCA/PKD and epilepsy.

Annexin 1 exerts anti-nociceptive effects after peripheral inflammatory pain through formyl-peptide-receptor-like 1 in rat dorsal root ganglion

BACKGROUND

Annexin 1 (ANXA1) has analgesic effects in inflammatory pain. We aimed to investigate the anti-nociceptive role of ANXA1, at the dorsal root ganglion (DRG) level, through an interaction with formyl-peptide-receptor-like 1 (FPR2/ALX).

METHODS

Inflammatory pain was evoked by injecting complete Freund's adjuvant (CFA, 50 μl) into the hindpaw of male Sprague-Dawley rats. The distribution of ANXA1 and FPR2/ALX in L4/5 DRGs was evaluated by immunofluorescence. The expression of ANXA1 was measured by western blot. The involvement of FPR2/ALX in the anti-nociception of ANXA1 was investigated by thermal (irradiant heat) and mechanical (von Frey filament) pain tests with intrathecal (i.t.) ANXA1-derived peptide (Anxa1(2-26)), FPR2/ALX agonist 5(S)-6(R)-7-trihydroxyheptanoic-acid-methyl-ester (BML-111), and antagonist N-t-Boc-Phe-Leu-Phe-Leu-Phe (Boc1).

RESULTS

ANXA1 and FPR2/ALX localized in the satellite glial cells and neurones in L4/5 DRGs. CFA treatment (n=20) increased ANXA1 expression in L4/5 DRGs within 7 days (P<0.01). I.T. Anxa1(2-26) (20 and 100 µg µl(-1)) and BML-111 (10 and 100 nmol) reduced CFA-induced thermal and mechanical nociception within 48 h (n=40) (P<0.05). However, i.t. Boc1 10 µg intensified inflammatory pain (P<0.05) and reversed the anti-nociceptive effect of Anxa1(2-26) (n=25) (P<0.05). Moreover, ANXA1 expression increased in L4/5 DRGs after i.t. Anxa1(2-26) (20 µg µl(-1)) (P<0.05) and BML-111 (10 nmol) (P<0.01) but decreased after i.t. Boc1 (10 and 100 µg) alone (P<0.01) or Boc1 (10 µg) co-injection with Anxa1(2-26) (20 µg µl(-1)) (P<0.05).

CONCLUSIONS

Endogenous ANXA1 expression at the DRG level is involved in CFA-induced inflammatory pain, and i.t. ANXA1 20 µg µl(-1) produces its anti-nociceptive effect through FPR2/ALX.

Relationships between DNA incorporation, mutant frequency, and loss of heterozygosity at the TK locus in human lymphoblastoid cells exposed to 3'-azido-3'-deoxythymidine

3'-Azido-3'-deoxythymidine (AZT), a thymidine analogue widely used in the treatment of AIDS patients and for prevention of the onset of AIDS in HIV-seropositive individuals, causes tumors in mice exposed as adults or in utero. The purpose of this study was to investigate the potential mechanisms of AZT mutagenicity and carcinogenicity by quantifying the incorporation of AZT into cellular DNA, measuring AZT-induced thymidine kinase (TK) mutant frequencies (Mfs), and determining the percentage of loss of heterozygosity (LOH) in spontaneous or AZT-induced TK mutants in the human lymphoblastoid cell line, TK6. Cells were exposed to 300 microM AZT for 0, 1, 3, or 6 days, or to 0, 33, 100, 300, or 900 microM AZT for 3 days (n = 5 flasks/group). The effects of exposure concentration on incorporation of AZT into cellular DNA were evaluated by an AZT radioimmunoassay, and the effects of duration and concentration of AZT exposure on the TK Mfs were assessed by a cell-cloning assay. AZT was incorporated into DNA in a dose-related manner at concentrations up to 300 microM, above which no further increase was observed. TK Mf increased with the extended duration and with incremental concentrations of AZT exposure. There was a positive correlation (P = 0.036, coefficient = 0.903) between AZT-DNA incorporation and AZT-induced TK Mfs, suggesting that AZT incorporation into cellular DNA has a direct role in the genotoxicity of AZT. Southern blot analyses indicated that 84% (6.2 x 10(-6)/7.4 x 10(-6)) of AZT-induced mutants were attributable to LOH, consistent with the known mechanism of AZT as a DNA chain terminator. Considering the importance of LOH in human carcinogenesis, AZT-induced LOH warrants further study.

Brain microdialysis and PK/PD correlation of pregabalin in rats

Pregabalin [PGB, (S)-3-isobutyl GABA, CI-1008] is a derivative of the inhibitory neurotransmitter g-aminobutyric acid (GABA). It has shown anticonvulsant, analgesia and anxiety activity in animal models. In this report, blood-brain barrier (BBB) influx and efflux of PGB were investigated with microdialysis at efficacious doses in rats. BBB influx (CLin) and efflux (CLout) permeability for pregabalin were 4.8 and 37.2 microL/min/g brain, respectively, following an intravenous infusion to rats. The results indicate that PGB is brain penetrable, supporting its anti-epilepsy and other CNS pharmacology. Significant anticonvulsant action of PGB was detected between 2 and 8 hr post oral dose, which is lag behind ECF drug concentrations lees. A PK/PD link model was used to describe the counter-clockwise hysteresis relationship between pregabalin brain ECF concentration and the anticonvulsant effect in rats. The resulting Ce (concentration in effect compartment) versus effect profile exhibits a sigmoidal curve and the calculated ECe50 and Keo values were 95.3 ng/mL and 0.0092 min-1, respectively. The small Keo value suggests that the effect is not directly proportional to the amount of pregabalin in the ECF compartment possibly due to inherent delay.

Particle-mediated intravascular delivery of oligonucleotides to tumors: associated biology and lessons from genotherapy

For a solid tumor to become life-threatening, an adequate blood supply has to be established. Although neovascularization has dire consequences for the host, it furnishes a common route through which tumors may be accessed and eradicated by drugs. The fact that a tumor's vasculature is relatively more permeable than that of healthy host tissue means selective delivery of drugs may be achieved. The role played by the cells making up the tumor vascular bed, vascular endothelial cells (VECs), has to be evaluated closely in attempts to design ways for enhancing drug delivery to solid tumors via the vasculature. The two major roles of VECs in the body, as barrier and as transport, are both highly pertinent to drug delivery. Our review examines how VECs may be manipulated in vivo to improve the selective delivery of carriers for oligonucleotide constructs to solid tumors. It also discusses how oligonucleotide drugs may be targeted against tumor VECs on the premise that by killing these cells, the tumor itself will perish. Cationic liposomes and microspheres are the major delivery vehicles discussed, with added analyses of such other nucleic acid carriers as nanospheres, dendrimers, and polyethyleneimine.

Electrical resistance and macromolecular permeability of retinal capillary endothelial cells in vitro

This study was undertaken to examine the ability of retinal capillary endothelial cells to retain blood-retinal barrier properties in vitro. Second passage bovine retinal capillary endothelial cells were grown to confluence on polycarbonate filters in two chamber systems coated with laminin, fibronectin and type IV collagen. The electrical resistances, permeability of 3H-insulin and expression of blood-brain barrier related enzymes by retinal cells was observed and compared with bovine aortic endothelial cells and bovine fibroblasts. The electrical resistance of retinal cells rose over the first week of culture, peaking after 5-9 days in culture. In eleven separate experiments (n = 5 for each experiment) the average peak resistance of retinal endothelial cells ranged from 89.3-186.6 with a mean average of 129.0 ohm.cm2. In one of these experiments, the peak electrical resistance of retinal cells was 149.0 +/- 10.3 compared with 34.8 +/- 6.8 for aortic cells and 37.8 +/- 3.8 ohm.cm2 for fibroblasts. The permeability coefficients of inulin were: retinal cells 0.17 +/- 0.09, aortic cells 3.47 +/- 1.58 (p = 0.015), fibroblasts 3.93 +/- 0.78 (p = 0.002) x 10(-6) cm/sec. Retinal cells expressed significantly higher activities of gamma-glutamyl transpeptidase and alkaline phosphatase than the other cell types. Treatment of the monolayers with the calcium ionophore, A23187, resulted in a reversible increase in permeability as has been described for peripheral vascular endothelium. We conclude that BRCEC retain at least some of their specialised barrier properties in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)