Multicomponent Plasmid Protects Mice From Spontaneous Autoimmune Diabetes

Type 1 diabetes is an autoimmune disease in which insulin-secreting β-cells are destroyed, leading to a life-long dependency on exogenous insulin. There are no approved disease-modifying therapies available, and future immunotherapies would need to avoid generalized immune suppression. We developed a novel plasmid expressing preproinsulin2 and a combination of immune-modulatory cytokines (transforming growth factor-beta-1, interleukin [IL] 10 and IL-2) capable of near-complete prevention of autoimmune diabetes in non-obese diabetic mice. Efficacy depended on preproinsulin2, suggesting antigen-specific tolerization, and on the cytokine combination encoded. Diabetes suppression was achieved following either intramuscular or subcutaneous injections. Intramuscular plasmid treatment promoted increased peripheral levels of endogenous IL-10 and modulated myeloid cell types without inducing global immunosuppression. To prepare for first-in-human studies, the plasmid was modified to allow for selection without the use of antibiotic resistance; this modification had no impact on efficacy. This pre-clinical study demonstrates that this multi-component, plasmid-based antigen-specific immunotherapy holds potential for inducing self-tolerance in persons at risk of developing type 1 diabetes. Importantly, the study also informs on relevant cytokine and immune cell biomarkers that may facilitate clinical trials. This therapy is currently being tested for safety and tolerability in a phase 1 trial (ClinicalTrials.gov Identifier: NCT04279613).

“I have failed to separate my HIV from this pain”: the challenge of managing chronic pain among people with HIV

Pain is a highly prevalent and burdensome symptom among people with HIV (PWH). This study aims to identify how the experience of living with HIV and chronic pain influences pain beliefs, health-seeking and pain management. Thirty-nine purposively sampled PWH with chronic pain (sample characteristics = 61% women, 79% Black, Asian and minority ethnic groups, 18% men who have sex with men, 45-54 median age category) participated in focus groups in London. Focus groups were co-facilitated with community members. Transcripts wereanalysed using a thematic approach. Findings revealed that HIV stigma, fractured care pathways, and general practitioners' lack of HIV training are barriers to supported pain management. Unaddressed pain results in poorer mental health and reduced quality of life, which has important clinical implications for HIV treatment adherence. Creating HIV-specific pain resources, activating social networks, and pain self-management techniques are potential solutions. Person-centred assessment and HIV training is needed to help clinicians identify PWH with chronic pain. Clear guidelines need to be developed to identify which health service providers are responsible for chronic pain management in PWH. This study generated a refined version of the Fear Avoidance Model that introduces a dimension of HIV-specific behaviours that impact PWHs seeking chronic pain management.

OP0284 AN AGENT-BASED SIMULATION OF THE EFFECTS OF VARYING TIME TO TREATMENT WITH BIOLOGICAL AGENTS ON PATIENT HEALTH AND COST IN AXIAL SPONDYLOARTHRITIS USING NATIONAL REGISTER DATA

Background:

Evaluating the long-term impacts of healthcare policies on patient’s health and treatment costs for people with axial spondyloarthritis (axSpA) is challenging due to its chronic nature, and the variation in individual patient journeys post-diagnosis. Agent-based simulations are a novel approach to interrogating this complexity, and allow the consequences of different policy scenarios on outcomes to be explored.

Objectives:

Develop and validate an agent-based simulation of the UK axial spondyloarthritis healthcare system, using real-world data.

Interrogate the effects of earlier biologic treatment on costs and patient outcomes.

Methods:

Anonymised data were obtained from the UK National Early Inflammatory Arthritis Audit, and BSR Biologics Register (BSRBR-AS). This provided data on 162 units, and 702 patients with 1,631 patient-years of follow-up. An agent-based model was designed and programmed on the Netlogo platform to simulate patients and units individually over time. New patients were created based on national disease prevalence statistics. Patients’ disease journeys were modelled with a Bath AS Disease Activity Index (BASDAI) score. The model included hospital outpatient attendances, treatment histories, drug costs, and key patient demographics. The baseline simulation was run for two simulated years, repeated 10 times, and assessed against the BSRBR-AS dataset for validation. The model was subsequently used to explore five experimental scenarios in which the time between the date of diagnosis, to first introduction to biologics (d-b) was varied by increasing the number of appointments. The experiment was run 10 times for each parameter setting.

Results:

In the baseline model in a typical two year run, 13,631 new patients attended 5,167 baseline, and 6,966 follow-up appointments. Of these, 6,324 and 623 were prescribed ≥1NSAID, and biologics, respectively. The validation comparison tests showed a high-level of similarity between simulated output and target datasets. In the target data, d-b was 250 days. In the experimental scenarios, as might be expected, earlier biologic access improved outcomes but at higher-costs (Figure 1; Table 1). Reducing d-b to 150 days doubled the number of patients on biologics at 2 years from 623 to 1,286. It also led to 8% more patients achieving a BASDAI of 0 to 2.5 at 2 years, with 5%, 1%, and 2% less patients achieving 2.5 - 5, 5 to 7.5 and 7.5 to 10 BASDAI, respectively. Reducing d-b to 150 days increased drug costs from £3.2 million to £8.8 million. However, the total number of appointments (a proxy for staff costs) increased proportionality less from 16,000 to 20,000.

Table 1.

Influence of varying the time between diagnosis to biologic treatment (d-b) on drug-use and staffing costs

Diagnosis to Biologic (d-b)Drug Costs Unit (£k)Total AppointmentsNo. patients prescribed NSAIDsNo. patients prescribed Biologics1508,79620,3847,1541,2832205,70218,5926,7969712503,25916,2146,3246212602,05414,7005,9683822651,29713,4115,562233Figure 1.

Influence of varying the time between diagnosis to biologic treatment (d-b) on 2 year BASDAI outcome

Conclusion:

We have successfully developed, and validated an agent-based approach to model the effect of key policy changes on the whole healthcare system, providing output estimates of cost and patient outcomes, based on integrated real-world data. To our knowledge this is the first attempt to explore the patient journey in people with axSpA in this way. The model provides a useful tool for exploring the effects of changing the way healthcare is delivered to patients with this disease. Our experimental analysis lends support to the case for increasing staffing and drug expenditure to achieve current NICE standards of care in AS.

Acknowledgments:

Financial support National Axial Spondyloarthritis Society (NASS), data access BSR.

Disclosure of Interests:

Alan Roach Grant/research support from: I was awarded an I-CRP grant from Pfizer for a similar simulation in RA, this was for about £50k and ran from 1/9/15 28/2/17., Ian Scott: None declared, Gary Macfarlane: None declared, Gareth T. Jones Grant/research support from: Pfizer, AbbVie, UCB, Celgene and GSK., Alex MacGregor: None declared

Deletion of the Mitochondrial Complex-IV Cofactor Heme A:Farnesyltransferase Causes Focal Segmental Glomerulosclerosis and Interferon Response

Mutations in mitochondrial DNA as well as nuclear-encoded mitochondrial proteins have been reported to cause tubulointerstitial kidney diseases and focal segmental glomerulosclerosis (FSGS). Recently, genes and pathways affecting mitochondrial turnover and permeability have been implicated in adult-onset FSGS. Furthermore, dysfunctioning mitochondria may be capable of engaging intracellular innate immune-sensing pathways. To determine the impact of mitochondrial dysfunction in FSGS and secondary innate immune responses, we generated Cre/loxP transgenic mice to generate a loss-of-function deletion mutation of the complex IV assembly cofactor heme A:farnesyltransferase (COX10) restricted to cells of the developing nephrons. These mice develop severe, early-onset FSGS with innate immune activation and die prematurely with kidney failure. Mutant kidneys showed loss of glomerular and tubular epithelial function, epithelial apoptosis, and, in addition, a marked interferon response. In vitro modeling of Cox10 deletion in primary kidney epithelium compromises oxygen consumption, ATP generation, and induces oxidative stress. In addition, loss of Cox10 triggers a selective interferon response, which may be caused by the leak of mitochondrial DNA into the cytosol activating the intracellular DNA sensor, stimulator of interferon genes. This new animal model provides a mechanism to study mitochondrial dysfunction in vivo and demonstrates a direct link between mitochondrial dysfunction and intracellular innate immune response.

Deficient Autophagy Results in Mitochondrial Dysfunction and FSGS

FSGS is a heterogeneous fibrosing disease of the kidney, the cause of which remains poorly understood. In most cases, there is no effective treatment to halt or retard progression to renal failure. Increasing evidence points to mitochondrial dysfunction and the generation of reactive oxygen species in the pathogenesis of CKD. Autophagy, a major intracellular lysosomal degradation system, performs homeostatic functions linked to metabolism and organelle turnover. We prevented normal autophagic pathways in nephrons of mice by mutating critical autophagy genes ATG5 or ATG7 during nephrogenesis. Mutant mice developed mild podocyte and tubular dysfunction within 2 months, profound glomerular and tubular changes bearing close similarity to human disease by 4 months, and organ failure by 6 months. Ultrastructurally, podocytes and tubular cells showed vacuolization, abnormal mitochondria, and evidence of endoplasmic reticulum stress, features that precede the appearance of histologic or clinical disease. Similar changes were observed in human idiopathic FSGS kidney biopsy specimens. Biochemical analysis of podocytes and tubules of 2-month-old mutant mice revealed elevated production of reactive oxygen species, activation of endoplasmic reticulum stress pathways, phosphorylation of p38, and mitochondrial dysfunction. Furthermore, cultured proximal tubule cells isolated from mutant mice showed marked mitochondrial dysfunction and elevated mitochondrial reactive oxygen species generation that was suppressed by a mitochondrial superoxide scavenger. We conclude that mitochondrial dysfunction and endoplasmic reticulum stress due to impaired autophagic organelle turnover in podocytes and tubular epithelium are sufficient to cause many of the manifestations of FSGS in mice.

Treatment for a eumycetoma infection caused by Aspergillus in an immunocompromised host: a case report

Eumycetoma is a chronic infection of the skin and subcutaneous tissue caused by filamentous fungi, which usually occurs in tropical or subtropical countries. We report a case of an immunocompromised patient presenting with presumed eumycetoma in the United States and his subsequent treatment with voriconazole. The use of voriconazole and liposomal amphotericin B halted the progression and allowed gradual resolution of the infection. The patient will require close monitoring and long-term therapy with voriconazole to obtain a clinical cure. Voriconazole and liposomal amphotericin B are potential initial treatment options, with long-term voriconazole maintenance therapy, for an Aspergillus-induced eumycetoma.

Observation of magnetocoriolis waves in a liquid metal Taylor-Couette experiment

The first observation of fast and slow magnetocoriolis (MC) waves in a laboratory experiment is reported. Rotating nonaxisymmetric modes arising from a magnetized turbulent Taylor-Couette flow of liquid metal are identified as the fast and slow MC waves by the dependence of the rotation frequency on the applied field strength. The observed slow MC wave is damped but the observation provides a means for predicting the onset of the magnetorotational instability.

Beneficial effects of r-h-CLU on disease severity in different animal models of peripheral neuropathies

Clusterin is a protein involved in multiple biological events, including neuronal cytoprotection, membrane recycling and regulation of complement-mediated membrane attack after injury. We investigated the effect of recombinant human clusterin in preclinical models of peripheral neuropathies. Daily treatment with clusterin accelerated the recovery of nerve motor evoked potential parameters after sciatic nerve injury. Prophylactic or therapeutic treatment of experimental autoimmune neuritis rats with clusterin also accelerated the rate of recovery from the disease, associated with remyelination of demyelinated nerve fibers. These data demonstrate that clusterin is capable of ameliorating clinical, neurophysiological and pathological signs in models of peripheral neuropathies.

Methods to enhance the safety of methotrexate prescribing

The treatment of chronic inflammatory conditions often involves a difficult balance between the benefits of disease modification and the risks attendant with the use of disease-modifying agents. Methotrexate is a useful and commonly used disease-modifying agent but has a particularly notable reputation for causing morbidity and mortality. We explore ways in which the safety of methotrexate prescribing may be improved. There has been considerable debate as to the whether some of the side-effects can be mitigated by co-prescription of folate with methotrexate. Whereas no definitive conclusion can yet be reached, evidence suggests that the improvement in side-effect profile is limited to fewer elevations of liver enzymes, but that this may be at the expense of decreased methotrexate efficacy. The question remains as to whether the improved tolerability more than compensates for the decreased efficacy or whether folic acid should be used in a more circumspect way. However, a very specific danger arises from the fact that methotrexate is prescribed once weekly for inflammatory conditions, leading to errors at both the prescription and patient level. We highlight simple ways of improving safety to decrease such errors.

The accumulation of Zn, Se, Cd, and Pb and physiological condition of Anadara trapezia transplanted to a contamination gradient in Lake Macquarie, New South Wales, Australia

The benthic bivalve, Anadara trapezia, was collected from a 'clean' reference site and transplanted along a suspected trace metal contamination gradient in Lake Macquarie, NSW. At monthly intervals, Zn, Se, Cd and Pb concentrations were measured in the surficial sediments and whole tissues of the cockle as well as their physiological condition (Scope for Growth). Zinc, Cd and Pb concentrations in sediments decreased together, southward, with the highest concentrations in the Cockle Bay area, suggesting that this is the main source of contamination. Zinc, Cd and Pb concentrations were near or above [ANZECC/ARMCANZ, 2000. National water quality management strategy paper 4. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand. pp. 3.5.-1-3.5-10] sediment quality guidelines at Cockle Creek, Warners Bay and Koorooa Bay. Significant differences in trace metal concentrations could not be attributed to grain size or Fe concentration differences. Se concentrations were highest in fine grain Fe rich sediments of Whiteheads Lagoon, and likely to be associated with power generation operations. Trace metal concentrations did not vary significantly over time. Zinc, Cd and Pb concentrations in the tissues of A. trapezia followed a similar pattern to that of sediments. Zinc and Pb concentrations in cockles and sediments were highly correlated, indicating significant exposure-dose relationships. Selenium concentrations in the tissues of A. trapezia were higher after transplantation to the lake, however, Se concentrations were similar in all transplanted cockles, indicating that Se in contaminated sediments is not the major source of Se to organisms. There was a decline in the physiological condition of A. trapezia transplanted to Lake Macquarie after a 90-day-period with marked differences in clearance rates and respiration rates at some locations and absorption efficiencies at all locations. The mean Scope for Growth value at the most contaminated location, Cockle Bay, was markedly lower than at other locations. A significant Zn exposure-dose response relationship indicates that Zn bioaccumulation is occurring in response to sediment contamination. A significant Cd exposure-response relationship indicates that Cd may be influencing the health of cockles. Significant Pb exposure-dose, exposure-response and dose-response relationships indicate that Pb probably is affecting the health of cockles in Lake Macquarie. Therefore, Zn, Cd and Pb concentrations in sediments are likely to be affecting the health of cockles in Lake Macquarie.

Formation of collisionless high-beta plasmas by odd-parity rotating magnetic fields

Odd-parity rotating magnetic fields (RMFo) applied to mirror-configuration plasmas have produced average electron energies exceeding 200 eV at line-averaged electron densities of approximately 10(12) cm-3. These plasmas, sustained for over 10(3)tauAlfven, have low Coulomb collisionality, vc* triple bond L/lambdaC approximately 10(-3), where lambdaC is the Coulomb scattering mean free path and L is the plasma's characteristic half length. Divertors allow reduction of the electron-neutral collision frequency to values where the RMFo coupling indicates full penetration of the RMFo to the major axis.

Positive-negative epitope-tagging of beta amyloid precursor protein to identify inhibitors of A beta processing

In this report, a novel positive-negative epitope tagging approach was developed to study the cellular processing of beta amyloid precursor protein (beta APP). Amino acids centered around the alpha-secretase cleavage site within the A beta sequence were replaced with residues comprising an epitope for which high-affinity monoclonal antibodies are commercially available. The resulting mutant beta APP cDNAs were expressed in human embryonic kidney cells (HEK 293). Cleavage of labeled beta APP by beta- and gamma-secretase(s) results in the release of an epitope-tagged A beta peptide, whereas cleavage by alpha-secretase results in destruction of the epitope. Highly sensitive and specific immunoassays were developed to study processing of this labeled beta APP via the amyloidogenic pathway. Secretion of epitope-tagged A beta was prevented by MDL 28170, a previously described gamma-secretase inhibitor. Confocal microscopic studies revealed that processing and cellular trafficking of epitope-tagged beta APP was not different from wild-type beta APP. These results suggest that positive-negative epitope-tagged beta APP is normally processed within the cell and may be used to identify secretase inhibitors as therapeutics for Alzheimer's disease.

Migrational analysis of the constitutively proliferating subependyma population in adult mouse forebrain

Initial experiments to evaluate the in vivo fate(s) of constitutively proliferating subependymal cells determined that, following in vivo labeling of this population by infection with a retrovirus containing a beta-galactosidase reporter gene, there was a progressive and eventually complete loss of histochemically beta-galactosidase-positive cells within the lateral ventricle subependyma with increasing survival times of up to 28 days after retroviral infection. Subsequent experiments were designed to ascertain the potential contributions of: (i) the migration of subependymal cells away from the forebrain lateral ventricles; and (ii) the down-regulation of the retroviral reporter gene expression. Retroviral lineage tracing experiments demonstrate that a major in vivo fate for constitutively proliferating subependymal cells is their rostral migration away from the walls of the lateral ventricle to the olfactory bulb. Although down-regulation of retroviral reporter gene expression does not contribute to the loss of detection of beta-galactosidase-labeled cells from the lateral ventricle subependyma, it does result in an underestimation of the absolute number of retrovirally labeled cells in the olfactory bulb at longer survival times. Furthermore, a temporal decrease in the double labeling of beta-galactosidase-labeled cells with [3H]thymidine was observed, indicating that only a subpopulation of the migratory subependymal-derived cells continue to actively proliferate en route to the olfactory bulb. These two events may contribute to the lack of a significant increase in the total number of retrovirally labeled subependymal cells during rostral migration. Evidence from separately published studies suggests that cell death is also an important regulator of the size of the constitutively proliferating subependymal population. In summary, in vivo studies utilizing retroviral reporter gene labeling demonstrate that constitutively proliferating subependymal cells born in the lateral ventricle migrate rostrally to the olfactory bulb. Loss of proliferation potential and retroviral reporter gene down-regulation contribute to the lack of any significant increase in the total number of labeled cells recovered in the olfactory bulb.

A novel phosphatase regulating neurite extension on CNS inhibitors

The inability of injured axons to regenerate in the adult mammalian central nervous system is thought to be in part due to inhibitory molecules synthesized by oligodendrocytes and present in myelin. We describe the cloning of a cDNA encoding a novel neuronal protein, named NERPP-2C, which is distantly related to protein phosphatase 2C and plays a role in the inhibitory response pathway to myelin inhibitors. NERPP-2C is expressed in neuronal cell lines and in rat brain. Expression in rat is detectable at E15, increases with age, and is highest in adulthood. Exposure of NG108-15 cells to antisense oligonucleotides reduces NERPP-2C expression and overcomes the inhibition of neurite extension on CNS myelin substrates in vitro. Antibodies to NERPP-2C detect two proteins, approximately 55 and 80 kDa in size, the smaller of which is found in the cytoplasm, and the larger is associated with the membrane fraction. The antibodies specifically immunoprecipitate a protein which exhibits serine/threonine and tyrosine phosphatase activity. NERPP-2C is localized in neurites and in growth cones, as well as in the cell nucleus. We hypothesize that NERPP-2C is a component in the signal transduction pathway for neuronal growth inhibitory factors in CNS myelin.

In vitro expression of endothelin-1 (ET-1) and the ETA and ETB ET receptors by the prostatic epithelium and stroma

RT-PCR analysis of total RNA prepared from the prostate cancer cell lines DU145 and PC3 and from primary epithelial cells indicated the presence of endothelin-1 (ET-1) messenger RNA (mRNA). Neither the LNCaP cell line nor primary prostatic stromal cells possess ET-1 mRNA transcripts. Seventy-two-hour-conditioned media derived from DU145, PC3, and primary epithelia contain immunoreactive ET concentrations equivalent to 0.814 +/- 0.048, 0.330 +/- 0.050, and 0.856 +/- 0.055 fmol/mL/10(6) cells after 72 h, respectively. Basal immunoreactive ET secretion was exhibited by LNCaP (0.029 +/- 0.009 fmol/mL/10(6) cells after 72 h) and stromal cells (0.067 +/- 0.007 fmol/ mL/10(6) cells after 72 h). Examination of ETA and ETB gene expression by RT-PCR demonstrates that ET receptor mRNA is almost completely undetectable in the prostate cancer cell lines. Both ETA and ETB mRNAs are detectable in primary cultures of prostatic epithelia and stroma. Competitive binding studies demonstrate a single class of binding site in both primary benign epithelia (dissociation constant = 1.85 x 10(-10) mol/L; maximal binding capacity = 2.7 x 10(4) binding sites/cell), and stroma (dissociation constant = 1.93 x 10(-10) mol/L; maximal binding capacity = 3.7 x 10(5) binding sites/cell). Use of selective ET receptor antagonists confirmed that the predominant stromal receptor subtype expressed in vitro is ETB. This receptor seems not to be coupled to mitogenic pathways because no growth response to exogenous ET-1 or cooperation between ET-1 and bFGF could be observed. Similarly, no effect of ET-1 or the ET-converting enzyme inhibitor, phosphoramidon, on benign epithelial cells could be observed over a 4-day period.

Human central nervous system myelin inhibits neurite outgrowth

In vitro and animal studies have identified molecules in mammalian CNS myelin which inhibit neuritic extension and which may be responsible, at least in part, for the lack of axonal regeneration after injury in the injured brain, optic nerve and spinal cord. To determine whether such inhibitory activity may be present in human CNS myelin, we used a bioassay to characterize neurite outgrowth on this substrate. Human CNS myelin strongly inhibited neuritic outgrowth from newborn rat dorsal root ganglion neurons and NG-108-15 cells, a neuroblastoma-glioma hybrid cell line. Similar but less potent inhibitory activity was identified in human gray matter. The CNS myelin inhibition of neuritic outgrowth appeared to be dependent on direct contact between the myelin substrate and neurites. The inhibitory activity in human CNS myelin closely resembled that described in adult rodents. Inhibition of neurite growth by human CNS myelin in this in vitro bioassay mirrors the lack of regeneration in vivo and can be used as a model to develop strategies designed to enhance axonal regeneration and neural recovery.

A convenient in vitro assay for the inhibition of neurite outgrowth by adult mammalian CNS myelin using immortalized neuronal cells

The adult mammalian CNS contains molecules which inhibit neurite outgrowth and which may be responsible for the lack of successful axonal regeneration after injuries in the brain and spinal cord. We describe an in vitro assay to measure the ability of primary and established lines of neuronal cells to produce neurites in the presence of CNS inhibitory molecules. The assay is suitable for identification of agents and treatments to overcome neurite growth inhibition. Assays are carried out in 96-well plates with CNS myelin substrates using NG108-15 cells, an immortalized cell line that can be induced to produce extensive neuritic growth. The inhibition of neurite outgrowth by CNS myelin observed in this assay is: (1) observed for NG108-15 cells and also PC12 cells and primary superior cervical ganglion neurons, (2) contact dependent, (3) half-maximal at 5 micrograms/cm2 of myelin, and (4) trypsin-labile. This assay is quantitative, rapid, highly reproducible, convenient and can be used to test compounds which have the potential to overcome the growth inhibitory molecules present in CNS myelin.

An antineuronal monoclonal antibody that reverses neurite growth inhibition by central nervous system myelin

A component of adult mammalian central nervous system (CNS) myelin causes collapse of neuronal growth cones and inhibits axonal growth, properties that may be responsible for the lack of regrowth of injured axons in the CNS. The molecules and detailed mechanism through which the inhibitory activity acts are not known. To study the cellular molecules mediating the response to this inhibitor, we have used an in vitro neurite growth inhibition assay to screen a panel of monoclonal antibodies raised against rat neuronal membrane proteins, for clones capable of blocking the response. One monoclonal antibody (10D) neutralized the inhibition of neurite growth seen when primary sympathetic neurons, PC12 cells or NG108-15 cells were grown on inhibitory CNS myelin substrates, but did not promote growth on non-inhibitory substrates. 10D reacted with neuronal cells but not myelin substrate proteins. The antigen recognized by 10D appears to play a role in the interaction between neurons and their growth substrates, and is a novel candidate for a cellular receptor or associated signalling molecule mediating the response to myelin inhibitors.

Regulation of intracellular calcium and preprotachykinin neurotransmitter precursor gene expression by patterned electrical stimulation in rat sympathetic neurons

Experiments were performed to test several predictions of the hypothesis that activity pattern-dependent changes in intracellular free calcium concentration ([Ca2+]i) might play a role in the translation of altered patterns of neuronal activity into changes in neurotransmitter gene expression. It was shown that (1) the Ca2+ channel blocker cadmium prevented depolarization-induced preprotachykinin-I (PPT-I) gene repression in rat sympathetic neurons; (2) the magnitudes of transient rises in [Ca2+]i were dependent upon the pattern in which a fixed number of depolarizing stimuli were delivered; and (3) stimulation at 10 Hz for 24 h did not repress PPT-I mRNA, while the same number of pulses delivered in 0.2 s bursts of 50 Hz caused a highly significant reduction to 30 +/- 2.5% of control levels.

Prophylaxis of atrial fibrillation with magnesium sulfate after coronary artery bypass grafting

Ninety-nine consecutive consenting patients were prospectively entered into a randomized, double-blind, placebo-controlled trial to determine the efficacy of postoperative magnesium therapy on the incidence of cardiac arrhythmias after elective coronary artery bypass grafting. No patient had documented or suspected arrhythmias preoperatively. Forty-nine patients received 178 mEq of magnesium given over the first 4 postoperative days, and 50 patients received only placebo. The clinical characteristics of both groups were similar. The preoperative mean serum magnesium concentration was similar in both study (1.90 mEq/L) and placebo (1.90 mEq/L) groups. The mean postoperative serum magnesium concentration in study patients was significantly elevated over postoperative days 1 through 4 when compared with preoperative levels (p less than 0.001). The postoperative mean serum magnesium concentration in control patients declined and remained significantly depressed through postoperative day 3 (p less than 0.001), but increased to preoperative levels by postoperative day 4. The mean serum magnesium concentration was significantly greater in the study patients as compared with the control patients over postoperative days 1 through 4 (p less than 0.001). Although there was no significant difference between groups with respect to episodes of ventricular arrhythmias, there was a significant decrease in the number of episodes of atrial fibrillation in the group receiving magnesium therapy (p less than 0.02). There were no recognized adverse effects of magnesium therapy. Prophylactic magnesium administration seems to lessen the incidence and severity of atrial fibrillation after coronary artery bypass grafting.

Regulation of myelin basic protein gene transcription in normal and shiverer mutant mice

We describe the measurement of myelin basic protein gene transcription rate, and of the accumulation of both mature mRNA and total transcripts from the myelin basic protein gene in brains from mice of wild-type and homozygous shiverer genotypes at several ages spanning postnatal development. In wild-type brains the accumulation of total transcripts as well as mature mRNA, and the transcription rate, all follow the same general pattern of rising sharply from a low level at birth to a peak at 20 days, and continuing at a somewhat reduced level into adulthood. Thus a major factor in the developmental regulation of myelin basic protein expression is the control of transcription rate. The shiverer mutation consists of a deletion of the 3' end of the myelin basic protein gene which completely prevents production of mature mRNA and protein, and results in severe dysmyelination and a trembling behavior. In shiverer brains, the transcription rates for the intact 5' end of the gene follow closely those seen in wild-type animals up to the age at which maximal myelination normally occurs. Total myelin basic protein transcripts follow a similar profile but at less than 5% the level seen in wild-type, and, as expected, no mature mRNA is detected. Thus the shiverer deletion does not remove information required for efficient, developmentally regulated transcription, and the low level of myelin basic protein gene transcripts in this mutant must be a result of their reduced stability. A higher than normal myelin basic protein gene transcription rate in older shiverer animals raises interesting questions regarding the regulatory mechanisms controlling myelinogenesis.

Post-transcriptional events are responsible for low expression of myelin basic protein in myelin deficient mice: role of natural antisense RNA

Myelin deficient mice (mld) are characterized by tandem duplication of the gene coding for myelin basic protein (MBP). The upstream gene contains a large inversion of the 3' region which includes exons 3-7, and therefore it cannot give rise to mature mRNA and functional protein. MBP and MBP mRNA concentrations in mld brains constitute only approximately 2% of the concentrations present in normal mice. The overall transcription rate of the Mbp gene is normal. In order to explain the discrepancy between mRNA concentration and transcription rate, we studied transcription of each individual gene. The two genes were transcribed independently, although some uninterrupted transcription could not be excluded. The rate of transcription of the upstream gene was higher than that of the downstream gene. This difference was reflected in the concentration of sense and antisense RNA found in nuclei. Our results indicate that the low concentration of the mature mRNA cannot be caused by transcriptional interference. High concentration of nuclear antisense RNA strongly suggests that post-transcriptional regulation occurs in mld mice through formation of double stranded RNA.

The duplicated myelin basic protein gene in mld mutant mice does not impair transcription

Myelin basic protein (MBP) gene organization and expression were analyzed in wild type and myelin deficient (mld) mutant mice. Southern analysis demonstrated MBP gene duplication in mld mice. In addition, we present evidence that one MBP gene in mld mice is normal for at least 14 kilobases (kb) upstream from exon I, whereas the second gene is normal for at least 3.5 kb but not more than 7 kb upstream from exon I. Run-on experiments showed that the rate of MBP gene transcription in mld mice is similar to that seen in normal mice. Detailed analysis of the transcriptional activity of various regions of the gene led us to conclude that all portions of the MBP gene are transcribed in mld mice. Consequently, we propose that the low levels of MBP mRNA observed in these mice (2-5% of the wild-type level) are not due to deficient transcriptional activity.

Depolarizing influences regulate preprotachykinin mRNA in sympathetic neurons

We have been studying mechanisms regulating neurotransmitter plasticity in sympathetic neurons. Neurons of the rat superior cervical ganglion (SCG) synthesize multiple putative transmitters, including the peptide substance P (SP). We have now examined steady-state levels of the mRNA encoding preprotachykinin (PPT), the SP precursor. A cloned cDNA probe was used to examine regulation mRNA levels in culture and in vivo. In RNA gel blot experiments, a single band (1.1 kilobases long) was observed in all cases in which an RNA was detected. A low level of PPT mRNA was detected by RNase protection assay in uncultured ganglia, suggesting that the low levels of SP previously observed in the normal ganglion in vivo are synthesized locally. When ganglia were maintained in culture, with consequent denervation, the steady-state level of PPT mRNA increased by 25-fold over the first 24 hr, and the high level was maintained for at least 7 days. RNase protection experiments indicated that the major message in the SCG is the beta-PPT mRNA, encoding both SP and neurokinin A peptide regions. Accumulation of the PPT mRNA in cultured ganglia was sharply inhibited by the depolarizing agent veratridine, and this effect was blocked by tetrodotoxin. Therefore, one form of neuronal plasticity, change in neurotransmitter metabolism, is regulated at least in part by altering steady-state levels of specific mRNA. More generally, extracellular signals may contribute to neuronal plasticity through changes in gene expression.

Chromosomal mapping of mouse myelin basic protein gene and structure and transcription of the partially deleted gene in shiverer mutant mice

The gene for mouse myelin basic protein (MBP) was mapped to chromosome 18 by hybridization of cloned MBP probes to DNA from hamster-mouse hybrid cell lines, showing it to be linked to the shiverer mutation which causes abnormal CNS myelination. Genomic blotting experiments show that in the mutants five of six exons which constitute the wild-type gene have been deleted. In shiverer brains the steady state level of transcripts that initiate correctly at the 5' end of the remaining exon 1 is reduced 16-fold. These RNAs are not spliced correctly and are not efficiently polyadenylated. It is proposed that the partial deletion of the MBP gene is an important part of the shiverer lesion.

Cloning and characterization of the myelin basic protein gene from mouse: one gene can encode both 14 kd and 18.5 kd MBPs by alternate use of exons

A mouse cosmid library was screened with a cDNA clone for rat small (M, 14,000) myelin basic protein (MBP). The entire MBP gene was isolated. Five exons were detected with the cDNA clone, which encode the Mr 14,000 MBP. A sixth exon, detected using a synthetic oligonucleotide, encodes the 41 amino acids specific to the Mr 18,500 form of MBP. Splicing together all six exons would give rise to Mr 18,500 MBP, while an mRNA omitting exon V would be translated to produce Mr 14,000 MBP. Further experiments indicate that there is probably a single MBP gene in the mouse genome, and that there is a single major 5' end for mouse MBP transcripts, 47 bp 5' of the initiator methionine codon.

Structure and expression of the egg-laying hormone gene family in Aplysia

Transcription of the egg-laying hormone (ELH) gene family was examined by characterizing homologous cDNA clones from abdominal ganglion and atrial gland cDNA libraries. All cDNAs contain an exon that spans the coding region (exon III) and one or two additional exons. The tissue-specific expression of the ELH gene family was confirmed by the observation that exon III encodes the ELH precursor protein in the bag cell transcripts and either the A or B precursor proteins in the atrial gland transcripts. The cDNA clones also contain 5' untranslated exons not present in the previously isolated genomic clones. One type of transcript has a 40-base pair segment, designated exon I, contiguous with exon III. A second type of transcript has an additional 149 base pairs of DNA, designated exon II, located between exons I and III. Several genomic clones containing exons I and II were isolated. DNA sequence analysis reveals that exons I and II are directly linked and that they are separated from exon III by an intervening sequence of at least 5 kilobases (kb). Consensus sequences for a putative promotor region and also for RNA splicing and polyadenylation were identified. From this work we can describe a prototype ELH gene complete with identified sequences necessary for the proper initiation of transcription and the subsequent processing of the transcript.

Transcription and expression of the herpes simplex virus tk gene inserted into proviral sequences of feline leukemia virus

Recombinant DNA molecules containing the herpesvirus tk gene inserted near the middle of a cloned feline leukemia virus proviral genome, in the same transcriptional orientation as the long terminal redundancies (LTRs), were used to transform human tk- cells. Analysis of RNA from cloned lines indicates that the 5' LTR promotes a high level of transcription which, as a result of differing RNA splicing and polyadenylation pathways, results in three large, abundant RNAs, two of which contain the entire tk coding region. The tk promoter itself initiates transcription of a smaller, relatively rare tk mRNA, of the same length and abundance as found in cells transformed with the tk gene alone. Assays indicate that there is little if any thymidine kinase (TK) enzymatic activity contributed by the abundant LTR-promoted transcripts. This is presumably due to inefficient initiation of tk translation from the longer LTR-initiated transcripts because of upstream AUG codons in the viral sequences. RNA blots indicate that the viral LTR is stronger as a promoter than the tk promoter. The results also indicate that about one-third of the LTR-initiated transcripts are polyadenylated at the tk poly(A) site, while the rest use the poly(A) site of the 3' LTR.

Intracoronary thrombolysis in patients with acute myocardial infarction: comparison of the efficacy of urokinase with streptokinase

The efficacy of intracoronary urokinase and streptokinase were compared in 80 patients with acute myocardial infarction in a prospective, randomized, double-blind study. Urokinase was infused into the occluded coronary artery at 6000 U/min, and streptokinase was infused at 2000 U/min. Maximal duration of infusion was 2 hr. The frequency of successfully opening the artery was similar for patients receiving urokinase (27 of 45, 60%) and those receiving streptokinase (20 of 35, 57%). Fibrinogen levels after infusion were measured in 63 patients. Nineteen of 29 streptokinase recipients had fibrinogen levels less than 100 mg/dl compared with levels of two of 34 urokinase recipients (p less than .001). Five of 45 (11%) patients receiving urokinase and 10 of 35 receiving streptokinase (29%) had bleeding complications (p less than .05). Major bleeding after early coronary artery bypass surgery was more frequent in the streptokinase group (four of five compared with a similar group of patients receiving urokinase (none of five). This study demonstrates that while urokinase and streptokinase have equal intracoronary thrombolytic efficacy, patients receiving urokinase have less systemic fibrinolysis and less perioperative bleeding with early surgery than do patients receiving streptokinase.

Characterization of cloned cDNA representing rat myelin basic protein: absence of expression in brain of shiverer mutant mice

A cDNA library was constructed from mRNA isolated from the brains of 18-day-old rats, the age at which myelin biosynthesis is maximal. A synthetic DNA probe synthesized based on reverse translation of the amino acid sequence of rat myelin basic protein (MBP) was used to select two cDNA clones encoding MBP. A 1.5 kb Eco RI fragment from one clone was completely sequenced. When translated, a portion of this sequence was identical at 126 of 127 positions with the reported amino acid sequence for small MBP from the rat. Brains from mice of the homozygous shiverer genotype contained neatly reduced amounts of MBP mRNA relative to wild type. A deletion of MBP sequences in the genome of shiverer mice was also demonstrated. cDNAs for MBP will allow molecular investigation of the role this gene plays in both dysmyelinating and demyelinating diseases, as well as questions of MBP biosynthesis.

The U3 portion of feline leukemia virus DNA identifies horizontally acquired proviruses in leukemic cats

The presence and location of DNA sequences related to the U3 and U5 portions of the infectious exogenous feline leukemia virus (FeLV) long terminal repeat (LTR) in various cat DNAs have been determined by hybridization experiments. In uninfected cat DNAs, the U5 LTR segment from the Gardner-Arnstein strain B virus is present at approximately 150 copies per cell. This level is approximately 10-fold greater than that of endogenous internal FeLV sequences. The U5 sequences differ in copy number and, to some extent, in location from one animal to another. For any one animal, the sequence organization of the U5 segments is the same among different tissues, showing that the pattern is inherited through the germ line. Most importantly, the viral U3 LTR probe hybridizes only very weakly with uninfected cat DNAs. Both the U3 and the U5 regions of the LTR from the Gardner-Arnstein strain of virus cross-hybridize with DNA derived from four other infectious FeLVs representing A, B, and C subtypes. Thus, the C3 region may be used as a probe for studying the number and location of exogenously acquired FeLV proviruses in infected cat tissues. In some cases exogenously acquired proviruses are present in unique sites in the genome of virus-positive cat lymphosarcomas, indicating a monoclonal origin for the tumor. In other tumors, the proviral sequences are randomly distributed over many sites. Lymphosarcomas of virus-negative cats have no exogenous U3 sequences despite epidemiological evidence of an association of virus-negative leukemia with exposure to FeLV.