The nociceptin receptor inhibits axonal regeneration and recovery from spinal cord injury

Axonal growth after traumatic spinal cord injury is limited by endogenous inhibitors, selective blockade of which promotes partial neurological recovery. The partial repair phenotypes suggest that compensatory pathways limit improvement. Gene expression profiles of mice deficient in Ngr1, which encodes a receptor for myelin-associated inhibitors of axonal regeneration such as Nogo, revealed that trauma increased the mRNA expression of ORL1, which encodes the receptor for the opioid-related peptide nociceptin. Endogenous and overexpressed ORL1 coimmunoprecipitated with immature NgR1 protein, and ORL1 enhanced the O-linked glycosylation and surface expression of NgR1 in HEK293T and Neuro2A cells and primary neurons. ORL1 overexpression inhibited cortical neuron axon regeneration independently of NgR1. Furthermore, regeneration was inhibited by an ORL1 agonist and enhanced by the ORL1 antagonist J113397 through a ROCK-dependent mechanism. Mice treated with J113397 after dorsal hemisection of the mid-thoracic spinal cord recovered greater locomotor function and exhibited lumbar raphespinal axon sprouting. These effects were further enhanced by combined Ngr1 deletion and ORL1 inhibition. Thus, ORL1 limits neural repair directly and indirectly by enhancing NgR1 maturation, and ORL1 antagonists enhance recovery from traumatic CNS injuries in wild-type and Ngr1 null mice.

Abstract 3432: Sex-dependent Differences in Autophagy After Experimentally-induced Stroke

Background and Purpose: Autophagy is a catabolic process where the cell consumes pieces of itself as a part of normal cellular growth, development, and homeostasis. In response to nutrient challenge or other stressors, including ischemia, autophagy levels may rise, enabling the cell to survive. Autophagy has been shown to play a role in the cellular response to neonatal cerebral ischemia, and sex differences have been found in cell culture models of neuronal nutrient starvation. However, the role of sex in the autophagic response to stroke has not been investigated in vivo . The objective of this study was to examine the impact of sex on autophagy following experimental stroke.

Methods: Stroke was induced by reversible right middle cerebral artery occlusion (MCAO - 90 minutes) in male, gonadally-intact female, and ovariectomized (OVX) WT C57BL/6 mice (20-25 gm). Autophagy activity was assessed at 6 and 24 hours following MCAO with LC3-I/II and Atg7 protein levels by western blot (n=3 MCAO; n=3 sham/group). Beta-actin was utilized as a loading control.

Results: Atg7 levels were higher in sham males at both the 6h and 24h timepoint compared to intact females and OVX females. After MCAO, males and OXV females showed increased levels of Atg7 relative to sham at 6h, while intact female levels were unchanged. By 24h, Atg7 levels in MCAO males and OVX females remained higher than sham, while intact females showed no difference. LC3-II levels were higher in MCAO for OVX females at 6h and 24h, while intact females saw transiently-elevated LC3-II levels at 6h and no elevation by 24h. Males had higher levels of LC3-II in both MCAO and sham relative to intact females at both 6h and 24h and higher levels than OVX females at 6h.

Conclusions: This study demonstrates that autophagy activation in response to stroke differs between the sexes. We found that males had overall higher levels of autophagy than both OVX females and intact females at both 6h and 24h. Both males and OVX females showed higher levels of autophagy at 24h and 6h after MCAO relative to sham, while females showed no change. Our study suggests that changes in autophagy may contribute to the differential outcome after stroke between the sexes. Studies examining sex differences in infarct size after MCAO after inhibition of autophagy with 3-methyladenine (3-MA, Sigma-Aldrich, St. Louis, MO) are ongoing in our laboratory.

HMG-CoA reductase inhibitors induce apoptosis in pericytes

Pericytes, which surround endothelial cells in precapillary arterioles, capillaries, and postcapillary venules, are important for the development, maturation, and maintenance of the vascular system. Pericytes are also pluripotent cells that can differentiate into a variety of mesenchymal cells including smooth muscle cells and osteoblasts. Possibly because of their vasculature regulating activities and ability to differentiate in situ, pericytes are implicated in several diseases with vascular complications, including diabetic retinopathy, as well as Reynaud's Syndrome, central nervous system dementias, and vascular calcification among others. Statin drugs, which block the conversion of HMG-CoA to mevalonate in the cholesterol synthesis pathway, are known to have apoptotic and growth inhibitory effects on cells in vitro and complex pleiotropic effects on cells and tissues in vivo. Recently, evidence has emerged that statin drug use in human patients results in a significant 20% reduction in cancer incidence. It is not known whether these results are due to direct statin action on normal tissue, growth inhibitory/pro-apoptotic effects on tumor cells, and/or effects on angiogenesis. Because of the role of pericytes in angiogenesis and the effects of statins on cancer incidence, we tested the direct effects of statins on pericytes. Specifically, we demonstrate that 3 statins, simvastatin, lovastatin, and mevastatin induce dose-dependent apoptosis in the TR-PCT1 pericyte cell line, that simvastatin (empirically shown to be the most potent of the 3 statins) induces similar levels of apoptosis in freshly isolated pericytes, and that simvastatin-induced apoptosis in pericytes is cholesterol, caspase-3, and caspase-7 mediated.

Cationic lipid structure and formulation considerations for optimal gene transfection of the lung

Enhanced gene transduction to the lung using cationic lipids could be attained through optimization of the structure of the lipids and the formulation of the cationic lipid:plasmid DNA (pDNA) complexes. We have expanded on our earlier observation of the importance of the structural orientation of the cationic lipid headgroup. Through the synthesis of a number of matched pairs of cationic lipids differing only in the configuration of their headgroup, we confirmed that those harboring a T-shape headgroup are more active than their linear counterparts, at least when tested in the lungs of BALB/c mice. Additionally, we demonstrated that not only are the structural considerations of these cationic lipids important, but also their protonation state, the free base being invariably more active than its salt counterpart. The salt forms of cationic lipids bound pDNA with greater avidity, which may have affected their subsequent intracellular dissolution and transit of the pDNA to the nucleus. Inclusion of a number of frequently used solutes in the vehicle severely inhibited the gene transfection activity of the cationic lipids. The selection of neutral co-lipids was also an important factor for overall transfection activity of the formulation, with significant gains in transfection activity realized when diphytanoylphosphatidylethanolamine or dilinoleoylphosphatidylethanolamine were used in lieu of dioleoylphosphatidylethanolamine. Finally, we showed that a transacylation reaction could occur between the cationic lipid and neutral co-lipid which reduced the transfection activity of the complexes. It is the hope that as our understanding of the many factors that influence the activity of these cationic lipid:pDNA complexes improves, formulations with much greater potency can be realized for use in the treatment of pulmonary diseases.

The history of DBCP from a judicial perspective

The efforts of workers in less-developed countries who have been exposed to 1,2-dibromo-3-chloropropane (DBCP) to obtain redress through the courts for damages suffered from these exposures are reported. The authors, who are lawyers, have represented more than 26,000 such workers. Evidence of the culpability of the U.S. manufacturers and the corporate users of DBCP, particularly Standard Fruit Company in Costa Rica, is presented. The damaged-worker plaintiffs are stymied by the application by the U.S. judicial system of forum non conveniens, which works in the defendants' favor by shunting the cases back to the plaintiffs' home countries, where the judicial systems are inadequate to deal with such cases and unlikely to be able to enforce judgments against the defendants.

Optimization of formulations and conditions for the aerosol delivery of functional cationic lipid:DNA complexes

We have examined several variables inherent in aerosolizing cationic lipid:DNA complexes using a jet nebulizer and thereby have optimized the delivery of functional complexes. Maximal aerosol transfer efficiency of cationic lipid:pDNA complexes was quantitated and shown to require the presence of at least 25 mM NaCL as an excipient. This is possibly related to effects on the measured zeta potentials of the complex, which indicate that the complexes are more highly charged in solutions of physiological ionic strength than in solutions of low ionic strength. Inclusion of saline also resulted in retention of the starting lipid to plasmid DNA (pDNA) ratio following nebulization. These data were used to design in vitro aerosolization experiments with tissue culture cells that resulted in the identification of a cationic lipid:pDNA ratio of 0.75:1 (mol:mol) as being optimal for aerosolization. This formulation largely protected pDNA from shear degradation during nebulization and produced a respirable aerosol droplet size (1-3 microns). It was tested further in a mouse model and shown to result in the dose-dependent transfection of mouse lungs, generating the equivalent of several picograms of reporter gene activity per mouse lung. The results of these experiments have provided a set of optimal conditions for nebulizing cationic lipid:pDNA complexes that can be used as a starting point for the further evaluation of aerosol delivery of these nonviral gene delivery vectors in vivo.

Detailed analysis of structures and formulations of cationic lipids for efficient gene transfer to the lung

Cationic lipid-mediated gene transfer of cystic fibrosis transmembrane conductance regulator (CFTR) cDNA represents a promising approach for treatment of cystic fibrosis (CF). Here, we report on the structures of several novel cationic lipids that are effective for gene delivery to the lungs of mice. An amphiphile (#67) consisting of a cholesterol anchor linked to a spermine headgroup in a "T-shape" configuration was shown to be particularly efficacious. An optimized formulation of #67 and plasmid vector encoding chloramphenicol acetyl-transferase (CAT) was capable of generating up to 1 microgram of CAT enzyme/lung following intranasal instillation into BALB/c mice. This represents a 1,000-fold increase in expression above that obtained in animals instilled with naked pDNA alone and is greater than 100-fold more active than cationic lipids used previously for CFTR gene expression. When directly compared with adenovirus-based vectors containing similar transcription units, the number of molecules of gene product expressed using lipid-mediated transfer was equivalent to vector administration at multiplicities of infection ranging from 1 to 20. The level of transgene expression in the lungs of BALB/c mice peaked between days 1 and 4 post-instillation, followed by a rapid decline to approximately 20% of the maximal value by day 7. Undiminished levels of transgene expression in the lung could be obtained following repeated intranasal administration of #67:DOPE:pCF1-CAT in nude mice. Transfection of cells with formulations of #67:DOPE:pCF1-CFTR generated cAMP-stimulated CFTR chloride channel and fluid transport activities, two well-characterized defects associated with CF cells. Taken together, the data demonstrate that cationic lipid-mediated gene delivery and expression of CFTR in CF lungs is a viable and promising approach for treatment of the disease.

A comparison of direct immunofluorescence, shell vial culture, and conventional cell culture for the rapid detection of influenza A and B

Direct immunofluorescence (FA) and shell vial contrifugation cultures (SVCs) were compared with conventional tube cultures for the rapid detection of influenza A and B by using a commercial antibody. Of the 439 specimens tested, 82 were positive by conventional culture (CC). The direct smear prepared from pelleted cells or direct swab material exhibited positive fluorescence in only seven (8.5%) of these cases, whereas the SVC was positive in 30 (37%). The SVC method detected 12 additional positive isolates that were not recovered in CC. The mean time to isolation in CC was 3.6 days for influenza A and 4.3 days for influenza B. The use of SVC provided more rapid results (36-48 hr). The FA method, although more rapid, may be of limited sensitivity and difficult to interpret depending on the quality of the specimen. The results indicate that SVC complements conventional culture in the rapid detection of influenza and can detect infections that may be missed in conventional tubes, but should not be used to the exclusion of conventional culture.

Rapid isolation of herpes simplex virus by using mink lung and rhabdomyosarcoma cell cultures

Highly sensitive and rapid results can be obtained by isolating herpes simplex virus from clinical specimens in simple cell culture with rhabdomyosarcoma (RD) cells. In this study, 3,186 clinical specimens were inoculated into locally produced, equivalent-age RD and mink lung (ML) cells. Of 727 positive isolates, all (100%) were isolated from RD cells and only 691 (95%) were isolated from ML cells. Furthermore, 162 of the positive isolates (22%) were isolated in RD cells earlier than in ML cells. RD cells are continuous and can be cultivated in house without decreasing sensitivity as the passage number increases. They produce a highly distinguishable cytopathic effect in response to herpes simplex virus and maintain intense confirmatory staining patterns.

Evaluation of direct immunofluorescence, enzyme immunoassay, centrifugation culture, and conventional culture for the detection of respiratory syncytial virus

Four methods of detecting respiratory syncytial virus (RSV) from clinical specimens were evaluated. A total of 410 specimens consisting of nasopharyngeal washes, aspirates, and swabs were simultaneously tested for the presence of RSV by direct immunofluorescence assay (DFA), enzyme immunoassay (EIA) (Kallestad Pathfinder), shell vial centrifugation culture (SVC), and conventional culture. DFA identified 146 (83%) of the 175 positive cases, EIA detected 153 (87%), SVC detected 127 (73%), and conventional culture detected 70 (40%). Conventional culture isolated an additional 19 respiratory viruses other than RSV. DFA and EIA were able to detect nonviable virus not isolated by a culture method, and SVC isolated low-titer virus not detected by conventional culture. DFA and EIA gave similar results; however, the EIA system was less dependent on technical expertise. The use of SVC enhanced the conventional culture system with 63 RSV isolates not recovered from the tube culture. We recommend complementary use of both culture and nonculture methods in the detection of RSV.

Presumptive identification of enteroviruses with RD, HEp-2, and RMK cell lines

The limited supply of the Lim Benyesh-Melnick antiserum pools for the typing of enteroviruses has made this test inappropriate for routine use in most clinical laboratories. We studied the correlation between the enterovirus groups and the cell lines on which they displayed cytopathic effect in order to make identifications without using the neutralization test. This study indicated that a presumptive identification of the enterovirus group could be made on the basis of characteristic cytopathic effect displayed after passage into rhabdomyosarcoma (RD), HEp-2, and primary rhesus monkey kidney (RMK) cells. Echoviruses and group A coxsackieviruses could be isolated in RD and RMK cells but not HEp-2 cells. Group B coxsackievirus could be isolated in RMK and HEp-2 cells but not RD cells. Poliovirus could be isolated in all three cell lines. We recommend the use of these cell lines to make presumptive enterovirus group identifications for routine viral isolates.

Comparison of enzyme immunoassay, shell vial culture, and conventional cell culture for the rapid detection of herpes simplex virus

Specimens submitted for the detection of herpes simplex virus (HSV) were inoculated into conventional cell-culture tubes and fresh MRC-5 shell vials. The shell vial centrifugation cultures (SVCs) were examined at 16 hr postinoculation for HSV by using type-specific monoclonal antibodies (SVC-FA); they were also analyzed for HSV antigen by using an enzyme-linked immunoassay (SVC-ELISA). Mink Lung (ML) and rhabdomyosarcoma (RD) cells were used in the cell-culture tubes. Of 182 specimens, 35 (19%) were positive in cell-culture tubes, 16 (9%) were positive by SVC-ELISA, and 22 (12%) were positive SVC-FA. All specimens that were positive by SVC-ELISA, SVC-FA, and in culture tubes displayed cytopathic effect (CPE) at 16 hr. Those specimens that had a negative ELISA and/or FA result and were positive in culture were evaluated for the time in which it took to detect CPE. At 16 hr, 48% of the positive tubes were detected; at 40 hr (second day), 83% of the positive tubes were detected; and by the third day, 94% were detected. The RD cell line displayed CPE at the same time or earlier than ML cells did in 92% of the positive cases. The sensitivity of the SVC-ELISA at 16 hr was 46% with 100% specificity. The sensitivity of the SVC-FA at 16 hr was 63% with 99% specificity. Given the increased sensitivity, rapid display of CPE, and reduced cost and handling time of cell cultures, our laboratory found that rapid SVC-ELISA and SVC-FA procedures for HSV detection have no clinical or laboratory advantage.