The promise of layer-specific neuroimaging for testing predictive coding theories of psychosis

Predictive coding potentially provides an explanatory model for understanding the neurocognitive mechanisms of psychosis. It proposes that cognitive processes, such as perception and inference, are implemented by a hierarchical system, with the influence of each level being a function of the estimated precision of beliefs at that level. However, predictive coding models of psychosis are insufficiently constrained-any phenomenon can be explained in multiple ways by postulating different changes to precision at different levels of processing. One reason for the lack of constraint in these models is that the core processes are thought to be implemented by the function of specific cortical layers, and the technology to measure layer specific neural activity in humans has until recently been lacking. As a result, our ability to constrain the models with empirical data has been limited. In this review we provide a brief overview of predictive processing models of psychosis and then describe the potential for newly developed, layer specific neuroimaging techniques to test and thus constrain these models. We conclude by discussing the most promising avenues for this research as well as the technical and conceptual challenges which may limit its application.

OP0212 MEN DIAGNOSED WITH INFLAMMATORY ARTHRITIS BEFORE THE AGE OF 40 YEARS HAVE A LOWER FERTILITY RATE THAN THOSE DIAGNOSED AFTER THE AGE OF 40 YEARS: RESULTS OF A LARGE MULTICENTER STUDY (IFAME-FERTILITY)

Background:

The effect of inflammatory arthritis (IA) on fertility has been mainly studied in women. Multiple factors associated with lower fertility rate in women can also be present in male patients with IA (1). The fertility rate in men with IA, however, has never been studied.

Objectives:

To describe the fertility rate (number of biological children per individual) of men with IA.

Methods:

We performed a multicenter cross-sectional retrospective study conducted in eight Dutch hospitals. Men with IA (Rheumatoid Arthritis (RA), Juvenile Idiopathic Arthritis (JIA) and Spondyloarthritis (SpA)) who were over 40 years old and indicated that their family size was complete were invited to participate. Men who were still planning on having biological children were excluded. Participants completed a digital questionnaire that included fertility-related questions and questions regarding their demographic and clinical information. To analyze the impact of IA on male fertility rate, patients were divided into groups according to the age at the time of their diagnosis: age<30 years, age 31-40 years and age>41 years.

Results:

In total 628 participants diagnosed with IA were included. The response rate 34.87%. Information regarding their age, age at diagnosis, clinical diagnosis and number of children is presented per group in Table 1. Regarding the total number of children per man, there was a statistically significant difference between the three groups (p=<0.005). The mean total number of children was significantly lower in men diagnosed at age<30 years (1.39 {SD 1.41}) and at age 31-40 years (1.60 {SD 1.35}) compared to those diagnosed after at age>41 years (1.88 {SD 1.14}). Compared to men from the general population of the Netherlands, the total number of children of men diagnosed at age>41 years was not statistically different (1.88 vs 1.80, respectively).

Table 1.

Participants’ basic demographic and clinical characteristics, including the number of biological children per men.

All patientsIA diagnosed at age <30 yearsIA diagnosed at age 31-40 yearsIA diagnosed at age >41 yearsTotal, n (%)628137 (21.82)149 (23.73)342 (54.46)Age, mean (SD)57.17 (9.98)53.01 (9.96)52.76 (7.35)61.06 (9.47)Diagnosis, n (%)•iRA297 (47.29)42 (30.66)67 (44.97)188 (55.32)•AJIA10 (1.59)10 (6.25)0 (0)0 (0)•ISpA (incl. PsA)320 (50.96)90 (65.69)83 (55.70)147 (42.98)Age at diagnosis, mean (SD)41.29 (13.08)26.27 (9.15)36.99 (5.66)49.98 (9.70)Disease duration, mean (SD)15.89 (11.88)26.48 (12.57)15.70 (8.52)11.30 (9.87)Number of biological children, mean (95% CI)1.71 (1.60-1.81)1.39 (1.15-1.63)a,b1.60 (1.38-1.82)a1.88 (1.75 -2.01)

a p< 0.05 compared to those diagnosed age >41 years

b p< 0.05 compared to those diagnosed age >31-40 years

Conclusion:

This is the largest study ever conducted to evaluate the impact of IA on male fertility. We demonstrated that men diagnosed with IA before and during their reproductive years have a lower fertility rate than those men diagnosed with IA after their reproductive years. Multiple mechanisms (biological and non-biological) can be responsible for this association. More research is needed to identify the causes of these lower fertility rates in men with IA.

References:

[1]Perez-Garcia LF, Te Winkel B, Carrizales JP, Bramer W, Vorstenbosch S, van Puijenbroek E, et al. Sexual function and reproduction can be impaired in men with rheumatic diseases: A systematic review. Semin Arthritis Rheum. 2020;50(3):557-73.

Figure 1.

Total number of biological children (mean and SD) per group.

Acknowledgements:

The authors would like to acknowledge Ron Buijs, data manager of the Department of Rheumatology of the Erasmus MC, for his technical support with regards to data collection.

Disclosure of Interests:

Luis Fernando Perez-Garcia Consultant of: Galapagos, Esther Röder: None declared, Robbert Goekoop: None declared, Johanna Hazes: None declared, Marc R Kok Consultant of: Novartis, Grant/research support from: Novartis, Petra Kok: None declared, Hieronymus TW Smeele: None declared, Ilja Tchetverikov: None declared, J.H. van der Kaap: None declared, Annette van der Helm - van Mil: None declared, Bouwe Krijthe: None declared, Radboud Dolhain Speakers bureau: UCB, Roche, Abbvie, Genzyme, Novartis, Consultant of: Galapagos, Grant/research support from: UCB

OP0211 PATERNAL INFLAMMATORY ARTHRITIS IS ASSOCIATED WITH A HIGHER RISK OF MISCARRIAGES: RESULTS OF A LARGE MULTICENTER STUDY (IFAME-FERTILITY)

Background:

The effect of inflammatory arthritis (IA) on pregnancy outcomes has been studied mainly in women. Paternal older age, sperm DNA integrity and certain genetic defects have been associated with worse pregnancy outcomes (1). However, pregnancy outcomes of partners of men with IA have never been studied.

Objectives:

To describe the pregnancy characteristics and outcomes of partners of men diagnosed with IA.

Methods:

We performed a multicenter cross-sectional retrospective study conducted in eight Dutch hospitals. Men with IA (Rheumatoid Arthritis (RA), Juvenile Idiopathic Arthritis (JIA) and Spondyloarthritis (SpA)) who were over 40 years old and indicated that their family size was complete were invited to participate. Participants completed a digital questionnaire that included pregnancy-related questions and questions regarding their demographic and clinical information. To analyze the impact of IA on pregnancy outcomes, pregnancies were classified into two groups; pregnancies that occurred after diagnosis of IA and before the diagnosis of IA.

Results:

In total 628 male participants diagnosed with IA were included. 408 men reported 897 singleton pregnancies that resulted in 794 live births. Regarding pregnancy characteristics, pregnancies conceived after diagnosis of IA had a higher mean paternal and maternal age at conception and a lower rate of spontaneous pregnancies (90.91 vs 96.60%, p=<0.005) (See Table 1). With regards to pregnancy outcomes, pregnancies conceived after receiving the diagnosis of IA had a lower rate of live births (86.36% and 89.22%, p=0.053) and a significant higher rate of miscarriages (12.27 vs 7.53%, p=<0.05). After correcting for maternal age and year of pregnancy, pregnancies conceived after the diagnosis of IA had a higher risk of miscarriages (OR 1.71 [CI 1.04-2.81], p<0.05). No statistically significant differences between the two groups were reported for the rates of abortions, preterm births and pregnancy complications.

Table 1.

Pregnancy characteristics and outcomes.

AllpregnanciesPregnancy afterdiagnosis of IAPregnancy before diagnosis of IAP valuePregnancy characteristicsTotal number of pregnancies897220677Maternal age at conception, mean (SD)29.00 (5.00)30.69 (5.16)28.45 (4.83)p<0.005Paternal age at conception, mean (SD)31.31 (5.72)34.27 (6.08)30.49 (5.34)p<0.005Spontaneous pregnancy, n (%)854 (95.21)200 (90.91)654 (96.60)p<0.005Pregnancy duration-months, median (IQR)39 (38-40)39 (38-40)39 (38-40)p=0.928Pregnancy outcomesLive births, n (%)794 (88.52)190 (86.36)604 (89.22)p=0.053Miscarriage, n (%)78 (8.70)27 (12.27)51 (7.53)p<0.05Abortion, n (%)25 (2.78)3 (1.36)22 (3.25)p=0.128*Medical indication5 (20.00)0 (0)5 (22.73)*Personal reasons20 (80.00)3 (100.00)17 (77.27)Pre-term birth149 (16.61)31 (14.09)118 (17.43)p=0.248Pregnancy complicationsNo complications during pregnancy, n (%)754 (84.34)184 (83.64)570 (84.57)p=0.741Hypertensive disorders(hypertension, pre/eclampsia), n (%)41 (4.57)8 (3.64)33 (4.87)p=0.445Gestational Diabetes Mellitus11 (1.28)2 (0.94)9 (1.38)p=0.619Growth restriction12 (1.34)1 (0.45)11 (1.65)p=0.193

Conclusion:

This is the largest study to describe the pregnancy characteristics and outcomes of partners of men diagnosed with IA and the first to demonstrate that paternal IA is associated with a higher risk of miscarriage. Prospective studies are needed to corroborate these findings.

References:

[1]Ibrahim Y, Johnstone E. The male contribution to recurrent pregnancy loss. Translational andrology and urology. 2018;7(Suppl 3):S317-S27.

Acknowledgements:

The authors would like to acknowledge Ron Buijs, data manager of the Department of Rheumatology of the Erasmus MC, for his technical support with regards to data collection.

Disclosure of Interests:

Luis Fernando Perez-Garcia Consultant of: Galapagos, Esther Röder: None declared, Robbert Goekoop: None declared, Marc R Kok Consultant of: Roche, Grant/research support from: Roche, Petra Kok: None declared, Hieronymus TW Smeele: None declared, Ilja Tchetverikov: None declared, Annette van der Helm - van Mil: None declared, J.H. van der Kaap: None declared, Bouwe Krijthe: None declared, Radboud Dolhain Speakers bureau: Abbvie, UCB, Genzyme, Novartis, Consultant of: Galapagos, Grant/research support from: UCB

Optimal Imaging of Remote Bodies Using Quantum Detectors

We implement a general imaging method by measuring the complex degree of coherence using linear optics and photon number resolving detectors. In the absence of collective or entanglement-assisted measurements, our method is optimal over a large range of practically relevant values of the complex degree of coherence. We measure the size and position of a small distant source of pseudothermal light, and show that our method outperforms the traditional imaging method by an order of magnitude in precision. Finally, we show that a lack of photon-number resolution in the detectors has only a modest detrimental effect on measurement precision and simulate imaging using the new and traditional methods with an array of detectors, showing that the new method improves both image clarity and contrast.

Nonreciprocal Transmission and Reflection of a Chirally Coupled Quantum Dot

We report strongly nonreciprocal behavior for quantum dot exciton spins coupled to nanophotonic waveguides under resonant laser excitation. A clear dependence of the transmission spectrum on the propagation direction is found for a chirally coupled quantum dot, with spin up and spin down exciton spins coupling to the left and right propagation directions, respectively. The reflection signal shows an opposite trend to the transmission, which a numerical model indicates is due to direction-selective saturation of the quantum dot. The chiral spin-photon interface we demonstrate breaks reciprocity of the system and opens the way to spin-based quantum optical components such as optical diodes and circulators in a chip-based solid-state environment.

Side-by-side secretion of Late Palaeozoic diverged courtship pheromones in an aquatic salamander

Males of the advanced salamanders (Salamandroidea) attain internal fertilization without a copulatory organ by depositing a spermatophore on the substrate in the environment, which females subsequently take up with their cloaca. The aquatically reproducing modern Eurasian newts (Salamandridae) have taken this to extremes, because most species do not display close physical contact during courtship, but instead largely rely on females following the male track at spermatophore deposition. Although pheromones have been widely assumed to represent an important aspect of male courtship, molecules able to induce the female following behaviour that is the prelude for successful insemination have not yet been identified. Here, we show that uncleaved sodefrin precursor-like factor (SPF) protein pheromones are sufficient to elicit such behaviour in female palmate newts (Lissotriton helveticus). Combined transcriptomic and proteomic evidence shows that males simultaneously tail-fan multiple ca 20 kDa glycosylated SPF proteins during courtship. Notably, molecular dating estimates show that the diversification of these proteins already started in the late Palaeozoic, about 300 million years ago. Our study thus not only extends the use of uncleaved SPF proteins outside terrestrially reproducing plethodontid salamanders, but also reveals one of the oldest vertebrate pheromone systems.

Superresolving multiphoton interferences with independent light sources

We propose to use multiphoton interferences from statistically independent light sources in combination with linear optical detection techniques to enhance the resolution in imaging. Experimental results with up to five independent thermal light sources confirm this approach to improve the spatial resolution. Since no involved quantum state preparation or detection is required, the experiment can be considered an extension of the Hanbury Brown-Twiss experiment for spatial intensity correlations of order N>2.

Diagnostic accuracy of mammography readers and their memory performance have no correlation with each other

INTRODUCTION

The study aims to determine if any association exists between visual memory performance and diagnostic accuracy performance in a group of radiologist mammogram readers.

MATERIALS AND METHODS

One hundred proven mammograms (23 with cancers) were grouped into 5 sets of 20 cases, with sets being of equal difficulty. Pairs of sets were presented in 5 reads (40 cases per read, order random) to a panel of 8 radiologist readers (either present or past screening readers, with experience range from <1 year to >20 years). The readers were asked to either 'clear' or 'call back' cases depending on need for further workup, and at post-baseline reads to indicate whether each case was 'new' or 'old' (i.e. remembered from prior read). Two sets were presented only at baseline (40 cases per reader), and were used to calculate the reader's false recollection rate. Three sets were repeated post-baseline once or twice (100 cases per reader). Reading conditions were standardised.

RESULTS

Memory performance differed markedly between readers. The number of correctly remembered cases (of 100 'old' cases) had a median of 10.5 and range of 0-58. The observed number of false recollections (of 40 'totally new' cases) had a median of 2 and range of 0-17. Diagnostic performance measures were mean (range): sensitivity 0.68 (0.54-0.81); specificity 0.82 (0.74-0.91); positive predictive value (PPV) 0.55 (0.50-0.65); negative predictive value (NPV) 0.89 (0.86-0.93) and accuracy 0.78 (0.76-0.83). Confidence intervals (CIs; 95%) for each reader overlapped for all the diagnostic parameters, indicating a lack of statistically significant difference between the readers at the 5% level. The most sensitive and the most specific reader showed a trend away from each other on sensitivity, specificity, NPV and PPV; their accuracies were 0.76 and 0.82, respectively, and their accuracy 95% CIs overlapped considerably. Correlation analysis by reader showed no association between observed memory performance and any of the diagnostic accuracy measures in our group of readers. In particular, there was no correlation between diagnostic accuracy and memory performance.

CONCLUSION

There was no association between visual memory performance and diagnostic accuracy as a screening mammographer in our group of eight representative readers. Whether a radiologist has a good or a bad visual memory for cases, and in particular mammograms, should not impact on his or her performance as a radiologist and mammogram reader.

Typhlophis ayarzaguenai Señaris, 1998 is a junior synonym of Typhlophis squamosus (Schlegel, 1839)

Abstract

In 1839, Schlegel described Typhlophis squamosus on the basis of a single specimen from Cayenne, French Guiana. Since then the species has been reported from Brazil, Guyana and Suriname. Relying only on the original description and a subsequent short description of the holotype of T. squamosus by Boulenger in 1893, Señaris described T. ayarzaguenai from Venezuela in 1998. Señaris' description of T. ayarzaguenai contains several errors and discrepancies and we argue that our observations justify the consideration of T. ayarzaguenai as a junior synonym of T. squamosus. The genus Typhlophis thus remains monotypic and T. squamosus is a widespread species in the Guiana Shield.

[The value and limitations of the body mass index (BMI) in the assessment of the health risks of overweight and obesity]

--The Body Mass Index (BMI) is used as a measure of overweight and obesity. In epidemiological studies age, sex and ethnic background all have to be taken into consideration, particularly when determining the health risk caused by the amount of body fat. --Caution should be observed when using the BMI as a measure for interpreting overweight and obesity as body composition can be highly variable yet have the same BMI. Therefore, BMI is not a reliable measurement of body composition in individuals particularly in older and younger people. --Excess body fat in the visceral depot poses a separate health risk. The BMI does not give any insight into regional body fat distribution. Waist circumference is a valid index of visceral fat accumulation and can therefore be used as an indicator of health risks associated with visceral obesity.

A real-life prospective health economic study of elective single embryo transfer versus two-embryo transfer in first IVF/ICSI cycles

BACKGROUND

We analysed the difference in maternal, neonatal and total costs after single (SET) versus double day 3 embryo transfer (DET).

METHODS

We performed a two-centre prospective study of women in their first IVF/ICSI cycle choosing between SET or DET. Infertility treatment data were gathered from a database; maternal and neonatal outcome data from a case report form (CRF); health economic data from medical acts registered in the CRF for the outpatient part and from hospital bills. SET was performed in 206/367 (56.1%) and DET in 161/367 (43.9%) women.

RESULTS

In all, 367 transfers yielded 186 positive pregnancy tests, 148 ongoing pregnancies and 136 live deliveries (50.7, 40.3 and 37.1% per embryo transfer) of which 15 (11.0%) were twins. Live birth rate was 37.4% for SET, 36.6% for DET. Intention-to-treat analysis showed differences for: duration of pregnancy (SET: 39.0 +/- 1.4 versus DET: 38.3 +/- 2.2 weeks; P = 0.055), percentage prematurity (8.5 versus 23.8%; P = 0.033), percentage of neonates hospitalized (5.7 versus 17.9%; P = 0.121) and duration of neonatal hospitalization (6.3 +/- 2.2 versus 10.3 +/- 10.1 days; P = 0.01). Total cost after DET was higher (SET: 4700 +/- 3239 versus DET: 8613 +/- 10 105; P = 0.105), due to significantly higher neonatal costs (451 +/- 957 versus 3453 +/- 8154; P < 0.001) and not to differences in maternal costs (4250 +/- 2882 versus 5160 +/- 4106; P = 0.152).

CONCLUSIONS

This prospective health economic study shows that transfer of a single top quality embryo is equally effective as, but substantially cheaper than, double embryo transfer in women <38 years of age in their first IVF/ICSI cycle.

A randomized trial comparing two laryngeal mask airway insertion techniques

This study was undertaken to compare laryngoscopic-guided LMA insertion with a standard insertion technique. A total of 149 patients undergoing elective general surgical and orthopaedic procedures were randomly divided into two groups. Study endpoints included ease of insertion, haemodynamic changes, local trauma bleeding, and postoperative sore throat. There were no statistically significant differences found. The laryngoscope may aid laryngeal mask airway insertion in some circumstances.

Quantum interferometric optical lithography: exploiting entanglement to beat the diffraction limit

Classical optical lithography is diffraction limited to writing features of a size lambda/2 or greater, where lambda is the optical wavelength. Using nonclassical photon-number states, entangled N at a time, we show that it is possible to write features of minimum size lambda/(2N) in an N-photon absorbing substrate. This result allows one to write a factor of N2 more elements on a semiconductor chip. A factor of N = 2 can be achieved easily with entangled photon pairs generated from optical parametric down-conversion. It is shown how to write arbitrary 2D patterns by using this method.

Epilepsy in practice

Epilepsy is a common and often neglected illness in developing countries requiring a conscious effort by health workers, especially at community level, to enhance access to regular treatment and to motivate patients to continue treatment. Effective new drugs have recently come on to the market. However, their high cost means that they often cannot be afforded by poor countries. Strengthening local and national level organizations may help to motivate health workers and the public, improving health services for those with epilepsy and preventing serious complications.

Resonance Raman spectroscopy of 2H-labelled spheroidenes in petroleum ether and in the Rhodobacter sphaeroides reaction centre

As a step towards the structural analysis of the carotenoid spheroidene in the Rhodobacter sphaeroides reaction centre, we present the resonance Raman spectra of 14-2H, 15-2H, 15'-2H, 14'-2H, 14,15'-2H2 and 15-15'-2H2 spheroidenes in petroleum ether and, except for 14,15'-2H2 spheroidene, in the Rb. sphaeroides R26 reaction center (RC). Analysis of the spectral changes upon isotopic substitution allows a qualitative assignment of most of the vibrational bands to be made. For the all-trans spheroidenes in solution the resonance enhancement of the Raman bands is determined by the participation of carbon carbon stretching modes in the centre of the conjugated chain, the C9 to C15' region. For the RC-bound 15,15'-cis spheroidenes, enhancement is determined by the participation of carbon-carbon stretching modes in the centre of the molecule, the C13 to C13' region. Comparison of the spectra in solution and in the RC reveals evidence for an out-of-plane distortion of the RC-bound spheroidene in the central C14 to C14' region of the carotenoid. The characteristic 1240 cm-1 band in the spectrum of the RC-bound spheroidene has been assigned to a normal mode that contains the coupled C12-C13 and C13'-C12' stretch vibrations.

Preservation of myelinated fibers for electron microscopy: a qualitative comparison of aldehyde fixation, microwave stabilisation and other procedures all completed by osmication

A qualitative comparison was made of a variety of electron microscopic preservation methods for nervous tissue, especially with respect to myelinated fiber areas. The methods studied were aldehyde perfusion/immersion fixation, aldehyde-tannic acid immersion fixation (stimulated by either microwave or conventional heating), microwave stabilisation, saline treatment with conventional heating (all with secondary osmication), and primary osmication. For all methods three morphological aspects, the ultrastructural quality of myelin sheath and axon and the coherence between the two were judged separately. It appears that the best version of each method studied is capable of providing a good overall ultrastructural result but always shows a preference for one or two of the three separate morphological aspects. When aiming at good axon quality together with good axon/myelin coherence, aldehyde perfusion/immersion, saline treatment or primary osmication are almost equivalent. Microwave stabilisation, on the other hand, can be chosen when good myelin quality has to be combined with good axon quality. For more specific purposes the following examples can be given. When excellent myelin quality is needed both microwave-stimulated aldehyde-tannic acid fixation or microwave stabilisation can be considered. When the preservation of the axon quality has priority the aldehyde-perfused tissue should be further immersed in a heated aldehyde-tannic acid solution. Primary osmication guarantees excellent axon/myelin coherence. Despite the differences in detail, a remarkable correspondence is stressed between the overall results of sometimes extremely different methods of tissue preservation. Probably they all guarantee a reliable reflection of the in vivo situation. With respect to the use of microwave irradiation for tissue preservation, it appeared that stabilisation procedures are rather capricious. However, if successful, the results are not inferior to those of aldehyde fixation.

Towards a vibrational analysis of spheroidene. Resonance Raman spectroscopy of 13C-labelled spheroidenes in petroleum ether and in the Rhodobacter sphaeroides reaction centre

We report resonance Raman spectra of the carotenoid spheroidene and its 14'-13C and 15'-13C substituted analogues in petroleum ether and bound to the reaction centre of Rhodobacter sphaeroides R26. The spectra in petroleum ether correspond to planar all-trans spheroidene while those of the reaction centres are consistent with a nonplanar 15,15'-cis spheroidene. The effect of 13C labelling is largest in the carbon-carbon double-bond stretching region. The 15'-13C substitution of the reaction centre bound spheroidene, however, hardly changes the C=C band as compared to that for the natural abundance spheroidene apart from a new weak band at 1508 cm(-1). This observation has been interpreted as a decoupling of the C15=C15' stretch from the other double-bond stretches in combination with a small intrinsic Raman intensity of this local mode for 15,15'-cis spheroidene.

Valproate and sodium currents in cultured hippocampal neurons

Cultured rat hippocampal neurons with short processes were investigated using the whole cell voltage clamp under conditions appropriate for isolating Na+ currents. After incubation of the neuron culture for a period of 15-30 min in 1 mM sodium valproate, several parameters of the Na+ current were changed. The peak Na+ conductance gp, measured using hyperpolarizing prepulses, was reduced by valproate in a voltage-dependent manner. In the membrane voltage range from -30 to +20 mV, this reduction showed a linear dependence on voltage, increasing from about zero to approximately 30% of gp, the maximum peak Na+ conductance of the neuron. At the holding voltage of -70 mV, the inactivation parameter h infinity decreased from 0.88 in the control to 0.64 in the valproate solution. This reduction originated mainly from a 10 mV shift in the sigmoid relation between h infinity and membrane voltage along the voltage axis to hyperpolarizing potentials. The decay of the maximum peak Na+ current (inactivation) could be fitted by a biexponential function. Time constants of the fast and slow component at -20 mV decreased in valproate by about 50%. Valproate also retarded the recovery from inactivation, as determined at the holding voltage. The sigmoid recovery from inactivation could reasonably be described by an exponential function with time constant tau r and delay time delta t. Both tau r and delta t increased more than 200% in valproate. Our results indicate that valproate affected the Na+ current in hippocampal neurons in a way that contributed to a considerable depression of Na+ reactivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Porcine tissue plasminogen activator. Immunoaffinity purification, structural properties and glycosylation pattern

Tissue plasminogen activator was purified in high yield from pig heart by immunoaffinity chromatography and characterized by analysis of the glycosylation pattern and the N-terminal amino acid sequence. Comparisons with the human enzyme reveals residue exchanges in the A-chain at positions 3 (porcine Arg/human Gln) and 5 (Thr/Ile), and in the B-chain at positions 6 (Tyr/Phe), 10 (Thr/Ala) and 20 (Val/Ala). The glycosylation pattern for the porcine activator was determined by endoglycosidase treatment followed by gel electrophoresis. The A-chain contains a single high-mannose type of N-linked glycan structure and the B-chain contains a complex type of oligosaccharide. A similar but not identical pattern has been observed for the human activator, purified from melanoma cells.

Assay characteristics and fibrin affinity of plasminogen activators of the intrinsic fibrinolytic system

Plasminogen activators (PA) in the euglobulin fraction of dextran sulfate activated plasma (DS-EF) were assayed on fibrin plates. Activity related to tissue plasminogen activator (t-PA) or urokinase (u-PA) was quantified by antiserum inhibition. The DS-EF contained 30% t-PA, 30% u-PA and 40-50% activity unrelated to t-PA or u-PA. The latter was completely inhibited by 1.7 mumol/1 C1-inhibitor (C1INH), the two former were less sensitive. Addition of flufenamate to the DS-EF (DS-EF/Fluf) from normal and two factor XII (F XII)-deficient plasmas increased their activities to the same high level. More than 50% of the activity was unrelated to t-PA or u-PA, 30-40% was u-PA and 5-10% t-PA related. After addition of fibrinogen to DS-EF/Fluf and clotting with thrombin, the remaining solution contained only about 30% of the total activity, including less than 10% u-PA. The epsilon-aminocaproic acid inhibition pattern obtained with the DS-EF was uniform, and thus different from the biphasic pattern obtained with the low fibrin affinity PA, two-chain urokinase. Thus, both the plasma u-PA and the major unidentified PA in plasma have affinity for fibrin.

Sequence of formation of molecular forms of plasminogen and plasmin-inhibitor complexes in plasma activated by urokinase or tissue-type plasminogen activator

The pathway of plasminogen transformation was studied in plasma, particularly in relation to fibrin formation and the subsequent stimulation of plasminogen activation. Plasminogen was activated by urokinase (low fibrin-affinity) or tissue-type plasminogen activator (high fibrin-affinity). Formation of 125I-labelled free and inhibitor-bound plasminogen derivatives was quantified after their separation by acetic acid/urea/polyacrylamide-gel electrophoresis. In plasma activator converted Glu-plasminogen (residues 1-790) into Glu-plasmin, which was complexed to alpha 2-plasmin inhibitor. When this inhibitor was saturated, Glu-plasmin was autocatalytically converted into Lys-plasmin (residues 77-790). No plasmin-catalysed Lys-plasminogen formation was observed. Upon fibrin formation, activation initially followed the same Glu-plasminogen-into-Glu-plasmin conversion pathway, and stimulation of plasminogen activation was only observed with tissue-type plasminogen activator. In agreement with the emergence of novel effector function, on early plasmin cleavage of fibrin [Suenson, Lützen & Thorsen (1984) Eur. J. Biochem. 140, 513-522] the fibrin-binding of Glu-plasminogen increased when solid-phase fibrin showed evident signs of degradation. This was associated with the formation of considerable amounts of the more easily activatable Lys-plasminogen, most of which was fibrin-bound. At the same time the rate of plasmin formation with urokinase increased over that in unclotted plasma and the rate of plasmin formation with tissue-type plasminogen activator accelerated. Altogether these processes favoured enhanced fibrin degradation. The rates of Lys-plasminogen and plasmin formation abruptly decreased after lysis of fibrin, probably owing to a compromised effector function on further fibrin degradation.

Fibrinolytic activity of cerebral tissue after experimental subarachnoid haemorrhage: inhibitory effect of tranexamic acid (AMCA)

The influence of tranexamic acid (AMCA) on the fibrinolytic activity induced by plasminogen activators (PA) of the cerebral leptomeninges, arteries and choroid plexus after artificial subarachnoid haemorrhage (SAH) was studied in 90 rabbits. SAH was induced by injection of 1-2 ml autologous blood into the suboccipital cistern. Half of the rabbits were given AMCA, 200 mg per kg body weight, in daily single i.v. injections. The rabbits were sacrificed after 3-5, 8-10 and 14-15 days respectively. Part of the leptomeninges, basilar artery and choroid plexus were removed for assaying PA by the histochemical fibrin slide and fibrin plate methods, using thiocyanate for extraction of plasminogen activator from the tissues. Quantitative assays for the fibrin plate method showed high PA in the arterial and meningeal tissues from the untreated animals 3-5 days after SAH. The PA had decreased to normal levels 8-10 days after SAH but increased again 14-15 days after SAH. A lower PA in the choroid plexus followed the same pattern. The concentration of the primary plasmin inhibitor in plasma had decreased to half of the normal value 8 days after SAH when compared to the concentration in pooled plasma from normal rabbits. In AMCA treated animals the meningeal PA, assayed by both methods, was decreased 3-5 days after SAH while no or an insignificant decrease in PA was seen 8-10 and 14-15 days after SAH. The PA of the arterial vessel wall and choroid plexus in the AMCA treated animals, assayed by the histochemical method, was moderately decreased 3-5 days after SAH, while no significant differences between untreated and AMCA treated animals were seen after 8-10 or 14-15 days when the tissues were assayed by either method. These findings indicate that AMCA suppresses PA primarily in the leptomeninges during the first few days after SAH and presumably before the meningeal fibrosis has developed.

Separation of plasminogen activators from human plasma and a comparison with activators from human uterine tissue and urine

Normal human plasma contains acid-stable as well as labile plasminogen activators. The activity of activators in plasma euglobulins was inhibited by EACA in an uniform pattern, similar to that obtained with the major activators in human uterine tissue or with the purified porcine tissue activator, but different from the patterns obtained with plasmin or with urokinase. Gel filtration at high ionic strength separated activators corresponding to particle sizes of 60,000 dalton and about 10,000 dalton, corresponding to two activators similarly obtained from human tissue. The 60,000 dalton activator was precipitated in the euglobulin fraction. Its concentration increased in plasma after exercise. The 10,000 dalton activator was found mainly in the supernatant. Gel filtration in 0.15 M solutions yielded activators in fractions of molecular sizes of 100-140,000 dalton and 200,000 dalton or larger. The activity of normal and exercise euglobulins was inhibited by antiserum to a plasminogen activator prepared from porcine tissue, but it was not inhibited by antiserum to urokinase. Plasminogen activators in human plasma euglobulins resembled immunochemically the activators in human uterine tissue.

Separation of plasminogen activators from human uterine tissue and a comparison with activators from human urine and porcine tissue

Three types of plasminogen activator could be distinguished in extracts from human uterine tissue. The activators differed in thermostability or in mode of inhibition by EACA. All the extracts contained stable as well as labile activators. The saline extracts were uniformly inhibited by increasing concentrations of EACA. Extracts made with 2 M ammonium thiocyanate were either uniformly inhibited by EACA or showed deflections indicating contamination with an activator, which was inhibited in a biphasic manner. It was possible to distinguish between: (1) An activator, abundantly present in the tissue, which was uniformly inhibited and stable. (2) Another uniformly inhibited activator, which was labile. (3) An activator, inhibited in a biphasic manner, similar to urokinase, which was present in varying amounts in uteri with the endometrium in the proliferative phase. Gel filtration of the uterine extracts showed two major activity peaks corresponding to particle sizes of 60,000 dalton and about 10,000 dalton. Antiserum to purified plasminogen activator, prepared from porcine ovaries, inhibited the activity of the human uterine extracts, but not the activities of human urokinase or urine. Urokinase antiserum in a concentration completely inhibiting human urine or urokinase, inhibited only 10% or less of the activities of human uterine extracts.

Purification of Porcine and Human Tissue Activator

Tissue activator from pig heart: A highly purified activator preparation from pig heart has been prepared, essentially using two affinity adsorbtion steps. 1) Affinity adsorbtion to fibrin and elution with potassium thiocyanate. 2) Affinity chromatography on Sepharose-arginine. The final product, which is obtained by gel filtration on Sephacryl S-200 contains according to SDS-polyacrylamide gel electrophoresis one main band with Mw 64000. Reduced samples still appear as one component but with Mw 31000. The specific activity is about 500000 IU/mg (WHO Reference Preparation for Urokinase) and the yield 15-25 %.

Tissue activator from human uterus: A highly purified preparation of human tissue activator has been prepared from uterus by an immunosorbent technique using antibodies produced in goats against the porcine tissue activator and coupled to Sepharose. A crude preparation from 1 kg uterus tissue and containing about 100000 IU tissue activator was adsorbed on 30 g of the immunosorbent. The activity was eluted with a KSCN-gradient. Further purification was obtained by affinity chromatography on Sepharose-arginine. The yield in the active fraction was 30-35 % and the specific activity 200000 to 300000 IU/mg. SDS-polyacrylamide gel electrophoresis showed one main band and 1-2 additional trace components.

Purification and Properties of a Porcine Tissue Plasminogen Activator and its Comparison with Activators from Human Uterine Tissue, Blood and Urine

A plasminogen activator was prepared from porcine ovaries by a simple procedure described earlier (Kok and Astrup, Biochemistry 8:79, 1969) and further purified by ion exchange chromatography on SE- or SP-Sepharose and affinity chromatography on Sepharose-lysine.

The preparation was homogeneous by gel electrophoresis at pH 3.5 and SDS-polyacrylamide electrophoresis(PAGE). The specific activity was about 4.5 x 106 A and A tissue activator units per mg protein (one tissue activator unit is comparable to 0.1 CTA urokinase unit in a fibrinolytic assay under specified conditions). The molecular size estimated by SDSPAGE corresponded to a Mw of 67000 dalton. After reduction with dithiothreitol the activator produced a single band corresponding to a Mw of 33500 dalton, indicating cleavage into two chains of equal size. Isoelectric focusing revealed several bands, which were active and with an isoelectric pH range of 7-8.

An activator from human uterine tissue and an activator in the euglobulin fraction from human plasma were similar to the porcine tissue activator in molecular size, estimated by gel filtration, and immunochemically. The porcine tissue activator differed from the activator from human urine in reactivity, molecular size and immunochemically.

(This work was supported by USPHS Grant HL-05020, NIH, National Heart and Lung Institute, to dr. Tage Astrup and by the Swedish Medical Research Council (project no. 13X 03906 07A).)