Capecitabine/oxaliplatin as first-line treatment for metastatic colorectal cancer: a meta-analysis

OBJECTIVE

A meta-analysis of randomized controlled trials (RCT) was carried out to determine the efficacy and safety of capecitabine plus oxaliplatin (CAPOX) or fluorouracil plus oxaliplatin (FUOX) as first-line treatment for metastatic colorectal cancer (MCRC).

METHOD

A literature search was conducted of the Cochrane Controlled Trials Register Databases, Medline, Embase, ISI databases and Chinese Biomedical Literature Database without exclusion of material published in any language. RCTs conducted between 1998 and 2008 of CAPOX compared with FUOX regimens were considered for inclusion. Statistical analyses were carried out using RevMan software.

RESULTS

Ten RCTs were included, involving 3208 patients. The meta-analysis showed that there were no statistically significant differences in tumour response rate (RR, 0.93; 95% CI, 0.87-1.01; P = 0.09), progression-free survival (PFS) (RR, 0.98; 95% CI, 0.94-1.01; P = 0.19), and overall survival (OS) (RR, 1.02; 95% CI, 0.97-1.07; P = 0.47) between CAPOX and FUOX regimen. However, symptoms of thrombocytopenia and hand-foot syndrome (HFS) were increased in the CAPOX regimen (RR, 1.89; 95% CI, 1.33-2.69; P = 0.0004 and RR, 3.40; 95% CI, 2.25-5.15; P < 0.00001 respectively), while neutropenia and leucopenia occurred more frequently in the FUOX regimen (RR, 0.29; 95% CI, 0.15-0.55; P = 0.0002 and RR, 0.41; 95% CI, 0.18-0.95; P = 0.04 respectively).

CONCLUSION

CAPOX was equivalent to FUOX in terms of tumour response rate, progression-free survival (PFS), and OS in first-line treatment for patients with MCRC, which may be considered as standard first-line treatment in patients with MCRC.

Bioengineered skin in diabetic foot ulcers

OBJECTIVE

Bioengineered skin (BS) has been shown to play an important role in the treatment of diabetic foot ulcers (DFUs). Whether BS in the therapy of DFU can improve the outcomes still remains uncertain. We performed a quantitative meta-analysis of available randomized controlled trials to determine the effectiveness and safety of BS in the treatment of patients with DFUs.

DESIGN AND METHODS

Comprehensive search strategies of various electronic databases were used for this study to evaluate the effectiveness and safety between BS and conventional treatment (CT) in patients with DFU, and only randomized controlled trials were adopted in our review. Search terms included 'bioengineered skin', 'tissue-engineering skin', 'human-tissue graft', 'human-skin device', 'living-skin equivalent' and 'diabetic foot', 'diabetic ulcer', 'diabetic wound'. Analysis outcomes included complete wound closure, complications, ulcer recurrence and adverse severe events (ASEs).

RESULTS

Seven randomized controlled trials on BS vs. CT were included, and 880 participants met inclusion criteria. Pooled analysis showed a significant effectiveness and safety advantages for BS treatment compared to CT for patients with DFUs. In analysis of complications, only statistically significant difference of infection was noted. And no included trials reported ASEs related to these treatments.

CONCLUSIONS

Based on the meta-analysis, patients with DFUs may benefit from the BS because of its high effectiveness and safety and reduced risk for infections in comparison to CT.

rtE218G, a novel hepatitis B virus mutation with resistance to adefovir dipivoxil in patients with chronic hepatitis B

Antiviral therapy is a potentially successful approach for the treatment of patients with Hepatitis B virus (HBV) infection. One antiviral agent is the nucleoside analogue adefovir dipivoxil (ADV). Its efficiency is compromised by the emergence of drug-resistant HBV mutants. Although three major ADV-resistant mutations of HBV are known, rtA181T/V and rtN236T, HBV mutations associated with ADV resistance have not been fully identified. We analyzed DNA sequences that covered a 244 base pair region of the HBV polymerase gene from patients with clinical manifestations of ADV resistance. A novel pattern of amino acid substitutions in HBV polymerase was detected in 26 out of 86 patients. This mutant exhibited a substitution of glycine for glutamic acid at residue 218 (rtE218G). Transient transfection of the HBV replication-competent construct including the rtE218G mutation was performed in HepG2 cells in order to determine the relevance of this mutation to ADV resistance. Phenotypic analyses demonstrated that the rtE218G mutation could independently confer resistance to ADV in vitro, with a 50% inhibitory concentration (IC(50)) 5.5-fold higher than wild-type HBV. RtE218G-mutated HBV also showed a decreased replication capacity in vitro, equal to 87% of wild-type HBV. The present study showed that the rtE218G mutation may be a novel ADV-resistant mutation. Further work will focus on resistance surveillance and cross-resistance analyses, and the molecular mechanisms involved.

Induction with and without antithymocyte globulin combined with cyclosporine/tacrolimus-based immunosuppression in renal transplantation: a meta-analysis of randomized controlled trials

OBJECTIVE

The objective of this study was to conduct a meta-analysis of randomized controlled trials (RCT) to compare the effectiveness and safety of induction with and without antithymocyte globulin (ATG) combined with cyclosporine/tacrolimus-based immunosuppression in renal transplantation.

METHODS

Trials were identified through a computerized literature search of PubMed, EMBASE, Cochrane controlled trials register, Cochrane Renal Group Specialized Register of RCTs, and Chinese Biomedical database. Two independent reviewers assessed trials for eligibility and quality, and then extracted data. Data were extracted for patient and graft survival, acute rejection, the incidence of Banff, cytomegalovirus (CMV) infection, leukopenia, and thrombocytopenia. Dichotomous outcomes were reported as relative risk (RR) with 95% confidence intervals (CI).

RESULTS

Four RCTs (892 patients) were identified. The data showed that induction with ATG was more beneficial than no induction with ATG to reduce the incidence of chronic rejection (RR 0.70; 95% CI, 0.57-0.84) and acute rejection within 6 months (RR 0.68; 95% CI, 0.49-0.96) and at 12 months (RR 0.67; 95% CI, 0.50-0.89) as well as Banff II episodes (RR 0.53; 95% CI, 0.30-0.91), but increased the incidences of CMV infection (RR 1.61; 95% CI, 1.27-2.04) and leukopenia (RR 3.88; 95% CI, 2.80-5.38) and thrombocytopenia (RR 2.92; 95% CI, 1.77-4.04). There was no statistical difference between patient or graft survival rates at 6 and 12 months, as well as the incidences of Banff III or Banff I after transplantation.

CONCLUSION

Based on available data induction with ATG was more efficient to reduce the rate of acute rejection episodes and chronic rejection responses after renal transplantation, but was associated with increased side effects, particularly CMV infections. It is important to provide the most benefit for an individual patient.

Snapin facilitates the synchronization of synaptic vesicle fusion

Synaptic vesicle (SV) fusion is a fine-tuned process requiring a concert of fusion machineries. Using cortical neurons from snapin-deficient mice, we reveal a role for Snapin in facilitating synchronous release. In addition to reduced frequency of miniature excitatory postsynaptic currents (mini-EPSCs) and smaller release-ready vesicle pool (RRP) size, snapin deficiency results in EPSCs with multiple peaks and increased rise and decay times, reflecting "desynchronized" SV fusion. These defects impair both synaptic precision and efficacy during sustained neurotransmission. Transient expression of Snapin not only rescues the slowed kinetics of EPSCs, but also further accelerates the rate found in wild-type neurons. Furthermore, expression of Snapin-C66A, a dimerization-defective mutant with impaired interactions with SNAP-25 and Synaptotagmin, reduces the RRP size but exhibits less effect on synchronized fusion. Our studies provide mechanistic insights into a dual role of Snapin in enhancing the efficacy of SV priming and in fine-tuning synchronous SV fusion.

Docking of axonal mitochondria by syntaphilin controls their mobility and affects short-term facilitation

Proper distribution of mitochondria within axons and at synapses is critical for neuronal function. While one-third of axonal mitochondria are mobile, a large proportion remains in a stationary phase. However, the mechanisms controlling mitochondrial docking within axons remain elusive. Here, we report a role for axon-targeted syntaphilin (SNPH) in mitochondrial docking through its interaction with microtubules. Axonal mitochondria that contain exogenously or endogenously expressed SNPH lose mobility. Deletion of the mouse snph gene results in a substantially higher proportion of axonal mitochondria in the mobile state and reduces the density of mitochondria in axons. The snph mutant neurons exhibit enhanced short-term facilitation during prolonged stimulation, probably by affecting calcium signaling at presynaptic boutons. This phenotype is fully rescued by reintroducing the snph gene into the mutant neurons. These findings demonstrate a molecular mechanism for controlling mitochondrial docking in axons that has a physiological impact on synaptic function.

Steroid Withdrawal Increases Risk of Acute Rejection but Reduces Infection: A Meta-Analysis of 1681 Cases in Renal Transplantation

OBJECTIVE

To evaluate the safety of steroid withdrawal in renal transplantation recipients.

METHODS

These following databases were searched: Medline (1966 to September 2005), OVID (1966 to 2004), Embase (1984 to 2004), Cochrane library (issue 4, 2005), Highwire (1849 to September 2005), American Transplant Congress (2005), Chinese Biomedicine database (CBM 1994 to 2005). The safety was measured by the following factors: patient and graft survival, acute rejection, chronic rejection, infection, serum creatinine. We performed meta-analysis by using Revman 4.2.7.

RESULTS

Nine randomized clinical trials were identified to have a steroid withdrawal and a steroid continuing group. They included 1681 patients: 845 with steroid withdrawal and 836 with continuing steroid. The risk of acute rejection after steroid withdrawal was two times higher than steroid-continuing group (RR 2.05; 95% confidence interval [CI]: 1.54, 2.72; P < .00001), while the incidence of opportunistic infection and urinary tract infection of steroid withdrawal group were lower than the control group (RR 0.80; 95%CI 0.64, 1.00; P = .05 vs RR 0.74; 95%CI, 0.60, 0.92; P = .004, respectively). The graft and patient survivals, chronic rejection, and serum creatinine were similar to the steroid continuing group.

CONCLUSION

Steroid withdrawal can significantly increase the risk of acute rejection episodes, but reduces the incidence of infection to a certain extent. To prophylaxis against serious infection, steroid withdrawal is worth considering using a sufficient immunosuppressive regimen. The key point is to balance the benefit and harm for the individual recipient.

Safety and immunogenicity of an oral, inactivated, whole-cell vaccine for Shigella sonnei: preclinical studies and a Phase I trial

Orally delivered, inactivated whole-cell vaccines are safe methods of inducing local and systemic immunity. To increase surface proteins associated with adherence and invasion, Shigella sonnei were grown in BHI broth containing deoxycholate. A whole-cell vaccine (SsWC) was then produced by formalin inactivation. In pre-clinical studies, the SsWC vaccine was immunogenic and protected against S. sonnei-induced keratoconjunctivitis in the guinea pig model. In a randomized, double-blind, placebo-controlled, Phase I study, 10 evaluable subjects received either three doses of SsWC on Days 0, 14, and 28 (N = 3); five doses of SsWC on Days 0, 2, 4, 6, and 28 (N = 4); or placebo (N = 3). Each dose contained 2.0 x 10(10) inactivated cells. Serum and fecal antibodies against SsWC, LPS, and IpaC were measured by ELISA. A > or = 4-fold increase in titer was considered significant. Both SsWC dosing regimens were well tolerated. No fever or severe gastrointestinal symptoms were noted by any of the vaccinated subjects. Antibody responses were similar in the two dosing groups. Serum IgG or IgA responses to SsWC were seen in six of seven vaccinees (86%), to LPS in four of seven (57%), and to IpaC in five of seven (61%). Fecal IgA responses to these three antigens developed in five of five, three of five, and three of five subjects, respectively. Among the seven vaccinees, geometric mean rises in serum IgA levels to all three immunogens were significant; IgG increases trended toward significance (paired one-tailed t-test). We conclude that SsWC was immunogenic and protective in animal studies and well tolerated and immunogenic in a Phase I trial.

The role of Snapin in neurosecretion: snapin knock-out mice exhibit impaired calcium-dependent exocytosis of large dense-core vesicles in chromaffin cells

Identification of the molecules that regulate the priming of synaptic vesicles for fusion and the structural coupling of the calcium sensor with the soluble N-ethyl maleimide sensitive factor adaptor protein receptor (SNARE)-based fusion machinery is critical for understanding the mechanisms underlying calcium-dependent neurosecretion. Snapin binds to synaptosomal-associated protein 25 kDa (SNAP-25) and enhances the association of the SNARE complex with synaptotagmin. In the present study, we abolished snapin expression in mice and functionally evaluated the role of Snapin in neuroexocytosis. We found that the association of synaptotagmin-1 with SNAP-25 in brain homogenates of snapin mutant mice is impaired. Consequently, the absence of Snapin in embryonic chromaffin cells leads to a significant reduction of calcium-dependent exocytosis resulting from a decreased number of vesicles in releasable pools. Overexpression of Snapin fully rescued this inhibitory effect in the mutant cells. Furthermore, Snapin is relatively enriched in the purified large dense-core vesicles of chromaffin cells and associated with synaptotagmin-1. Thus, our biochemical and electrophysiological studies using snapin knock-out mice demonstrate that Snapin plays a critical role in modulating neurosecretion by stabilizing the release-ready vesicles.

Transgenic twin lambs cloned by granulosa cells

The development potential of transgenic adult cells after nuclear transfer (NT) was evaluated. Primary ovine granulosa cells (GC(S)) from a slaughter ovary were transfected with pEGFP-N1 plasmid DNA. Three G418-resistance cell lines (A2, B2 and B4) were used as donor cells in NT. A total of 162 NT blastocysts were then frozen with ethylene glycol solution and stored for five months before transplanted into recipients. Twenty-nine frozen thawed NT blastocysts were transferred into 15 synchronized recipients. Twin lambs (6.9%) derived from B2 line were delivered by cesarean section on day 143 but died after birth. A tumor consisting of lung tissues was found on the surface of left lung of the 4-kg lamb and histological analysis indicated that it resembles a hamartoma. DNA analysis confirmed that two lambs were genetically identical to B2 donor cells. Gene insertion and expression have been detected in fibroblasts cells derived from muscle tissues of the lambs. This study indicates that granulosa cell is a suitable cell type for producing transgenic animals by nuclear transfer. Offspring were produced after long-term storage of NT blastocysts.

Ca2+-dependent phosphorylation of syntaxin-1A by the death-associated protein (DAP) kinase regulates its interaction with Munc18

Syntaxin-1 is a key component of the synaptic vesicle docking/fusion machinery that binds with VAMP/synaptobrevin and SNAP-25 to form the SNARE complex. Modulation of syntaxin binding properties by protein kinases could be critical to control of neurotransmitter release. Using yeast two-hybrid selection with syntaxin-1A as bait, we have isolated a cDNA encoding the C-terminal domain of death-associated protein (DAP) kinase, a calcium/calmodulin-dependent serine/threonine protein kinase. Expression of DAP kinase in adult rat brain is restricted to particular neuronal subpopulations, including the hippocampus and cerebral cortex. Biochemical studies demonstrate that DAP kinase binds to and phosphorylates syntaxin-1 at serine 188. This phosphorylation event occurs both in vitro and in vivo in a Ca2+-dependent manner. Syntaxin-1A phosphorylation by DAP kinase or its S188D mutant, which mimics a state of complete phosphorylation, significantly decreases syntaxin binding to Munc18-1, a syntaxin-binding protein that regulates SNARE complex formation and is required for synaptic vesicle docking. Our results suggest that syntaxin is a DAP kinase substrate and provide a novel signal transduction pathway by which syntaxin function could be regulated in response to intracellular [Ca2+] and synaptic activity.

SNAP-29: a general SNARE protein that inhibits SNARE disassembly and is implicated in synaptic transmission

Using the yeast two-hybrid system with syntaxin-1A as bait, we isolated soluble NSF attachment protein (SNAP)-29 from a human brain cDNA library. Synaptosomal fractionation and immunocytochemical staining of hippocampal neurons in culture showed that SNAP-29 is present at synapses and is predominantly associated with synaptic vesicles. The interaction of SNAP-29 with syntaxin-1 was further confirmed with immunoprecipitation analysis. Binding competition studies with SNAP-29 demonstrated that it could compete with alpha-SNAP for binding to synaptic SNAP receptors (SNAREs) and consequently inhibit disassembly of the SNARE complex. Introduction of SNAP-29 into presynaptic superior cervical ganglion neurons in culture significantly inhibited synaptic transmission in an activity-dependent manner. Although SNAP-29 has been suggested to be a general SNARE component in membrane trafficking, our findings suggest that it may function as a regulator of SNARE complex disassembly and modulate the process of postfusion recycling of the SNARE components.

Functional studies using antibodies against orphanin FQ/nociceptin

Orphanin FQ/nociceptin (OFQ) is a recently discovered endogenous ligand for the novel opioid receptor-like receptor (ORL-1). There are numerous reports in the literature demonstrating paradoxical effects of exogenous OFQ on pain modulation. For example, OFQ produces a pronociceptive effect in the brain and an analgesic effect in the spinal cord. In order to better understand the physiological actions of OFQ, the present study focused on the pain-modulatory effect of endogenously released OFQ measured using antibody microinjection techniques. We found that electroacupuncture analgesia (EA) was increased by intracerebroventricular (i.c.v.) injection of an OFQ-antibody and decreased following intrathecal injection. Furthermore, i.c.v. OFQ-antibody partially reversed tolerance to both chronic morphine and chronic EA. These data suggest that endogenously released OFQ plays an important role in pain modulation, where pain sensitivity in the brain and spinal cord is increased and decreased, respectively.

Nocistatin reverses the effect of orphanin FQ/nociceptin in antagonizing morphine analgesia

Nocistatin is a recently characterized neuropeptide derived from the preprohormone containing nociceptin (Orphanin FQ, OFQ). Nocistatin was reported to antagonize OFQ induced allodynia, hyperalgesia and prostaglandin E2-elicited pain responses. The aim of the present study was to determine whether nocistatin, injected intracerebroventricularly (i.c.v.), would reverse the anti-morphine effect of OFQ in rats using the tail-flick latency (TFL) as the nociceptive index. I.c.v. injection of nocistatin at doses of 0.005, 0.05, 0.5, 5, 50, and 500 ng produced no significant changes in the basal TFL, nor did it affect morphine analgesia. However, it significantly reversed the antagonistic effect of OFQ on morphine analgesia when co-injected i.c.v. at doses of 0.05, 0.5, 5, 50 and 500 ng per rat with OFQ. The dose-response curve was bell-shaped and the most effective dose was 0.5 ng. The results suggest that nocistatin can reverse the anti-morphine effect of OFQ in rat brain.

Multicentre trial on the efficacy and toxicity of single-dose samarium-153-ethylene diamine tetramethylene phosphonate as a palliative treatment for painful skeletal metastases in China

A multicentre trial was organized in China as part of an international coordinated research project to study the efficacy and toxicity of single-dose samarium-153 ethylene diamine tetramethylene phosphonate (EDTMP) as a palliative treatment for painful skeletal metastases. One hundred and five patients with painful bone metastases from various primaries were treated with 153Sm-EDTMP at a dose of 37 MBq/kg(group I) or 18.5 MBq/kg (group II). The effects were evaluated according to change in daily analgesic consumption, pain score, sum of effect product (SEP), Physician's Global Assessment (PGA), blood counts, and organ function tests conducted regularly for 16 weeks. Fifty-eight of 70 patients in group I and 30 of 35 in group II had a positive response, with SEPs of 22.29+/-14. 47 and 20.13+/-13.90 respectively. Of 72 patients who had been receiving analgesics, 63 reduced their consumption. PGA showed that the Karnofsky score (KS) increased from 58.54+/-25.90 to 71.67+/-26. 53, indicating improved general condition, but the difference was not significant. Among subgroups of patients, only those with breast cancer showed a significant change in the Karnofsky score after treatment. Inter-group differences were found for net change in KS between patients with lung and patients with breast cancer, and between patients with lung and patients with oesophageal cancer. Seventeen patients showed no response. No serious side-effects were noted, except for falls in the white blood cell (nadir 1.5x10(9)/l) and platelet (nadir 6.0x10(10)/l) counts in 44/105 and 34/105 cases, respectively. Ten patients had an abnormal liver function test. Response and side-effects were both independent of dose. In conclusion, 153Sm-EDTMP provided effective palliation in 83.8% of patients with painful bone metastases; the major toxicity was temporary myelosuppression. Further studies are needed to identify better ways of determining the appropriate dose in the individual case and the efficacy of treatment.

Definition of T cell epitopes within the 19 kDa carboxylterminal fragment of Plasmodium yoelii merozoite surface protein 1 (MSP1(19)) and their role in immunity to malaria

MSP1(19) is one of the leading malaria vaccine candidates. However, the mechanism of protection is not clear. To determine whether MSP1(19)-specific effector T cells can control parasitaemia, we analysed the specificity of T cells induced following immunization with recombinant forms of P. yoelii MSP1(19) and asked whether they could protect mice. There was no evidence that effector T cells were capable of protecting since: (1) immunization of mice with yMSP1(19), but not defined epitopes, was able to induce protection; and (2) long term MSP1(19)-specific CD4+ T cell lines were incapable of adoptively transferring protection. In contrast, priming mice with the T cell epitopes resulted in a rapid anamnestic antibody response to MSP1(19) after either challenge with MSP1(19) or parasite. Thus, MSP1(19) contains multiple T cell epitopes but such epitopes are the targets of helper T cells for antibody response but not of identified effector T cells capable of controlling parasitaemia.

Endogenous orphanin FQ: evidence for a role in the modulation of electroacupuncture analgesia and the development of tolerance to analgesia produced by morphine and electroacupuncture

1. Our previous work has demonstrated that exogenously administered orphanin FQ (OFQ) antagonizes morphine analgesia and electroacupuncture analgesia (EAA) in the brain and potentiates morphine analgesia and EAA in the spinal cord of the rat. In the present study we evaluated the role of endogenously released OFQ in the development of tolerance to morphine and electroacupuncture (EA) and the analgesia produced by electroacupuncture, by use of the IgG fraction of an anti-OFQ antibody (OFQ-Ab) microinjected into the rat central nervous system (CNS). 2. EAA was produced by stimulating rats at a frequency of 100 Hz. Rats were classified as either high responders (HR) or low responders (LR) based on the analgesic effects of EA. LRs could be converted into HRs by the intracerebroventricular (i.c.v.) microinjection of OFQ-Ab at both 1:1 and 1:10 dilutions but not 1:100. HRs could be changed into LRs by the intrathecal (i.t.) injection of OFQ-Ab at both 1:1 and 1:10 dilutions, but not 1:100. 3. Acute morphine tolerance was induced in rats by repeated subcutaneous (s.c.) injections of morphine (5 mg kg, every 2 h) for 16 h. When injected i.c.v. the OFQ-Ab (1:1 dilution) had no effect on the development of acute morphine tolerance. 4. Chronic morphine tolerance was produced in rats by repeated injection of morphine (5-60 mg kg, s.c., 3 x a day) for 6 days. I.c.v. injection of OFQ-Ab (1:1 dilution) reversed this type of morphine tolerance in rats by 50% (P < 0.01). 5. Acute tolerance to the analgesia produced by EA developed after 6 h of continuous (100 Hz, 3 mA) stimulation. This tolerance was almost completely reversed by the i.c.v. injection of OFQ-Ab (1:1 dilution) (P < 0.05). 6. Chronic tolerance to the analgesic effect of EA was produced by repeatedly administering increasing current (1, 2 and 3 mA, each lasting for 10 min, for a total of 30 min) at a frequency of 100 Hz once a day for 6 days. I.c.v. injection of OFQ-Ab (1:1 dilution) reversed this kind of tolerance by 50% (P < 0.01). 7. Together these results suggest that 100 Hz EA may enhance the release of endogenous OFQ in the CNS of the rat, which in turn may act to antagonize EA-produced analgesia in the brain but potentiate EA produced analgesia in the spinal cord. Therefore, OFQ appears to play an important role in the development of tolerance to the analgesic effects produced by EA. 8. The mechanisms underlying the development of acute morphine tolerance and chronic morphine tolerance appear to be different. Central OFQ may play an important role in the development of tolerance after chronic morphine administration.

Complete protective immunity induced in mice by immunization with the 19-kilodalton carboxyl-terminal fragment of the merozoite surface protein-1 (MSP1[19]) of Plasmodium yoelii expressed in Saccharomyces cerevisiae: correlation of protection with antigen-specific antibody titer, but not with effector CD4+ T cells

The 19-kDa carboxyl-terminal fragment of the merozoite surface protein-1 (MSP1) is a leading malaria vaccine candidate but is unable to induce immunity in all monkeys or all strains of mice. The mechanism of immunity is unclear, although data show that cell-mediated immunity plays a critical role following immunization with the larger mature MSP1 protein. We optimized a vaccine protocol using the MSP1(19) fragment of Plasmodium yoelii expressed in Saccharomyces cerevisiae, such that following exposure of mice to parasites, they remained undetectable in peripheral blood, whereas control animals all died at very high parasitemia within 10 days. We then depleted the vaccinated mice of >99% of CD4+ T cells by anti-CD4 mAb treatment and could show that infections in most animals remained subpatent following challenge. Furthermore, mice in which the gene for the mu-chain of Ig had been disrupted could not be immunized with MSP1(19). Immunity in normal mice did not depend on the presence of an intact spleen nor production of nitric oxide, persisting unabated when >70% of splenic macrophages were depleted. Thus, while effector CD4+ T cells may contribute to immunity, neither they nor factors associated with a Th1-type cell mediated immune response appeared to play the major role in MSP1(19)-induced protection in normal mice. Furthermore, T cells were not sufficient for immunity in mice lacking B cells. In normal mice, protection correlated with a very high titer of MSP1(19)-specific Abs (>6,400,000), predominantly G1 and G2b, which may function by merozoite neutralization.

Complete protective immunity induced in mice by immunization with the 19-kilodalton carboxyl-terminal fragment of the merozoite surface protein-1 (MSP1[19]) of Plasmodium yoelii expressed in Saccharomyces cerevisiae: correlation of protection with antigen-specific antibody titer, but not with effector CD4+ T cells

The 19-kDa carboxyl-terminal fragment of the merozoite surface protein-1 (MSP1) is a leading malaria vaccine candidate but is unable to induce immunity in all monkeys or all strains of mice. The mechanism of immunity is unclear, although data show that cell-mediated immunity plays a critical role following immunization with the larger mature MSP1 protein. We optimized a vaccine protocol using the MSP1(19) fragment of Plasmodium yoelii expressed in Saccharomyces cerevisiae, such that following exposure of mice to parasites, they remained undetectable in peripheral blood, whereas control animals all died at very high parasitemia within 10 days. We then depleted the vaccinated mice of &gt;99% of CD4+ T cells by anti-CD4 mAb treatment and could show that infections in most animals remained subpatent following challenge. Furthermore, mice in which the gene for the mu-chain of Ig had been disrupted could not be immunized with MSP1(19). Immunity in normal mice did not depend on the presence of an intact spleen nor production of nitric oxide, persisting unabated when &gt;70% of splenic macrophages were depleted. Thus, while effector CD4+ T cells may contribute to immunity, neither they nor factors associated with a Th1-type cell mediated immune response appeared to play the major role in MSP1(19)-induced protection in normal mice. Furthermore, T cells were not sufficient for immunity in mice lacking B cells. In normal mice, protection correlated with a very high titer of MSP1(19)-specific Abs (&gt;6,400,000), predominantly G1 and G2b, which may function by merozoite neutralization.

Comparison of protection induced by immunization with recombinant proteins from different regions of merozoite surface protein 1 of Plasmodium yoelii

Vaccination with native full-length merozoite surface protein 1 (MSP1) or with recombinant C-terminal peptides protects mice against lethal challenge with virulent malaria parasites. To determine whether other regions of MSP1 can also induce protection, Plasmodium yoelii MSP1 was divided into four separate regions. Each was expressed in Escherichia coli as a fusion protein with glutathione S-transferase (GST). The N-terminal fragment began after the cleavage site for the signal sequence and ended in the region comparable to the cleavage site for the C terminus of the 82-kDa peptide of Plasmodium falciparum. This expressed protein was 30 kDa smaller than the predicted peptide. One peptide from the middle region was produced, and the C terminus consisted of a 42-kDa fragment corresponding to the analogous peptide of P. falciparum and a 19-kDa fragment that extended 37 amino acids in the amino-terminal direction beyond the probable cleavage site. To test protection of mice against lethal P. yoelii challenge, three mouse strains (CAF1, BALB/c, and A/J) were vaccinated with each of the four recombinant proteins of MSP1. Mice vaccinated with the C-terminal 19-kDa protein were highly protected (described previously), as were those vaccinated with the 42-kDa protein that contained the 19-kDa fragment. The N-terminally expressed fragment of P. yoelii was not full length because of proteolytic cleavage in E. coli. The GST-82-kDa partial fragments induced some immunity, but the surviving mice still had high parasitemias. Vaccination with the peptide from the middle region of MSP1 gave minimal to no protection. Therefore, in addition to the C-terminal 19- and 42-kDa proteins, the only other fragment to give protection was the 82-kDa protein. The protection induced by the truncated 82-kDa protein was minimal compared with that of the C-terminal fragments.

[Antagonistic effect of orphanin FQ on morphine analgesia in rat brain]

The discovery of a novel receptor-opioid receptor-like (ORL) receptor (1994) and its endogenous ligand-Orphanin FQ (OFQ) (1995) represented a new approach in the study of opioids and anti-opioids in CNS. Based on the high homology of ORL receptor and OFQ with their opioid family counterparts, as well as the high expression of ORL receptor mRNA and protein in the brain areas associated with nociception, the effect of OFQ on morphine induced analgesia in the rat brain was further investigated. The results showed that: (1) Intracerebroventricular (i.c.v.) injection of OFQ reversed the stress analgesia induced by i.c.v. injection of normal saline, which seems to be mediated by endogenous opioid peptides. (2) I.c.v. injection of OFQ dose-dependently antagonized morphine-induced analgesia dose-dependently. (3) I.c.v. injection of antisense oligodeoxynucleotide for the gene encoding ORL receptor to block the expression of ORL receptor in the CNS potentiated the analgesia induced by cumulative injection of morphine. The results suggest that OFQ seems to play a role of anti-opioid peptide in the rat brain.

[2 Hz and 100 Hz electroacupuncture accelerate the expression of genes encoding three opioid peptides in the rat brain]

Previous findings from this laboratory have shown that low (2 Hz) and high (100 Hz)-frequency electroacupuncture (EA) accelerated the release of different kinds of opioid peptides in the CNS. In the present study, we tried to elucidate whether EA of different frequencies would affect the transcription of genes encoding different opioid peptides. Digoxin-labeled antisense cRNA probes were used for in situ hybridization to detect the mRNA encoding preproenkephalin (PPE), preprodynorphin (PPD) and proopiomelanocortin (POMC) in the rat brain. The results showed that: (1) Neither 2 Hz nor 100 Hz EA altered the POMC mRNA level in the rat brain. (2) EA of the two frequencies induced a similar degree of increase of PPE mRNA in rostromedial reticular formation (gigantocellular, paragigantocellular and lateral reticular nucleus); whereas in supraoptic nucleus, suprachiasmatic nucleus, arcuate nucleus, paraventricular hypothalamic nucleus, ventromedial nucleus and the nucleus of lateral lemniscus, 2 Hz EA induced a higher PPE mRNA expression than 100 Hz EA. (3) 100 Hz EA markedly increased the PPD mRNA levels in supraoptic nucleus, paraventricular hypothalamic nucleus, ventromedial nucleus and parabrachial nucleus, while 2 Hz was without effect. Since de novo peptide synthesis is regarded as a natural outcome following accelerated peptide release, the present results substantiate our previous observation that EA of different frequencies exert different acceleratory effects on the release and synthesis of different opioid peptides in the central nervous system.

Bidirectional modulatory effect of orphanin FQ on morphine-induced analgesia: antagonism in brain and potentiation in spinal cord of the rat

1. The present study was designed to investigate further the effects of the newly discovered orphanin FQ (OFQ)-the endogenous ligand for the orphan opioid receptor (called, e.g., ORL, and LC132)-on pain modulation in the rat. We used the tail-flick assay as a nociceptive index. 2. When injected into a cerebral ventricle, OFQ (4 fmol-10 nmol) has no effect on basal tail-flick latency by itself at any dose, but dose-dependently antagonizes systemic morphine analgesia (400 fmol 50 nmol). 3. Injected intrathecally, OFQ (3 and 10 nmol) displayed an analgesic effect without producing motor dysfunction, and potentiated morphine analgesia (1 and 10 nmol). 4. The anti-opioid effect of OFQ in rat brain and the high level of expression of LC132/ORL, receptor in the locus coeruleus indicated a possible role of OFQ in the precipitation of opiate withdrawal symptoms. However, no such precipitation was observed by OFQ in morphine-dependent rats.

Involvement of endogenous orphanin FQ in electroacupuncture-induced analgesia

Recent studies suggest that the novel opioid peptide orphanin FQ (OFQ) is involved in pain modulation. We found that intracerebroventricular (i.c.v.) administration of OFQ in the rat produced a dose-dependent antagonism of the analgesia induced by 100 Hz electroacupuncture (EA) stimulation as measured in the radiant heat tail-flick assay. Antisense oligonucleotides injected i.c.v. potentiated EA analgesia, presumably by interfering with the expression of the OFQ receptor in brain. These results suggest that endogenous OFQ exerts a tonic antagonistic effect on EA-induced analgesia. No such antagonism was observed when OFQ was injected intrathecally (i.t.). Rather, it appears that spinal OFQ produced a marked analgesic effect and enhanced EA-induced analgesia. These findings are consistent with the experimental results obtained in rats where morphine-induced analgesia is antagonized by i.c.v. OFQ and potentiated by i.t. OFQ.