High-Valence Surface-Modified LMO Cathode Materials for Lithium-Ion Batteries: Diffusion Kinetics and Operando Thermal Stability Investigation

Lithium manganese oxide (LiMn2O4) is a prevalent cathode material for lithium-ion batteries due to its low cost, abundant material sources, and ecofriendliness. However, its capacity fade, low energy density, and fast auto-discharge hinders its large-scale commercialization. Consequently, scientists are urged to achieve high-performance LMO cathodes through material doping and surface modification using a wide range of transition metals, polymers, and carbon precursors. Few studies have considered the potential of high-valence transition metal oxides in stabilizing the LMO's cycling process and enhancing the overall battery performance. In this work, we report the synthesis of surface-modified lithium manganese oxide using high-valence tungsten oxide (WVIO3). Different WO3 wt % were investigated before settling for 0.5%WO3-LMO as the synergic surface-modified LMO. Using galvanostatic charge-discharge, 0.50 WO3-LMO exhibited better rate capability by retaining 51% of its initial capacity at a 20C rate, compared to 34% for the pristine LMO. Furthermore, cyclic voltammetry at different scan rates showed that 0.50 WO3-LMO possesses better ion diffusion than pristine LMO, around 10-11 and 10-13 cm2·s-1 respectively. Finally, using in situ Raman spectroscopy, reaction mechanisms during cycling were investigated, and operando accelerating rate calorimetry (ARC) visualized the surface-modified LMO's cycling thermal stability and highlighted its potential use for safe high-voltage lithium-ion batteries in automotive applications.

Frequency-Dependent Squeezed Vacuum Source for the Advanced Virgo Gravitational-Wave Detector

In this Letter, we present the design and performance of the frequency-dependent squeezed vacuum source that will be used for the broadband quantum noise reduction of the Advanced Virgo Plus gravitational-wave detector in the upcoming observation run. The frequency-dependent squeezed field is generated by a phase rotation of a frequency-independent squeezed state through a 285 m long, high-finesse, near-detuned optical resonator. With about 8.5 dB of generated squeezing, up to 5.6 dB of quantum noise suppression has been measured at high frequency while close to the filter cavity resonance frequency, the intracavity losses limit this value to about 2 dB. Frequency-dependent squeezing is produced with a rotation frequency stability of about 6 Hz rms, which is maintained over the long term. The achieved results fulfill the frequency dependent squeezed vacuum source requirements for Advanced Virgo Plus. With the current squeezing source, considering also the estimated squeezing degradation induced by the interferometer, we expect a reduction of the quantum shot noise and radiation pressure noise of up to 4.5 dB and 2 dB, respectively.

Search for Subsolar-Mass Binaries in the First Half of Advanced LIGO's and Advanced Virgo's Third Observing Run

We report on a search for compact binary coalescences where at least one binary component has a mass between 0.2  M_{⊙} and 1.0  M_{⊙} in Advanced LIGO and Advanced Virgo data collected between 1 April 2019 1500 UTC and 1 October 2019 1500 UTC. We extend our previous analyses in two main ways: we include data from the Virgo detector and we allow for more unequal mass systems, with mass ratio q≥0.1. We do not report any gravitational-wave candidates. The most significant trigger has a false alarm rate of 0.14  yr^{-1}. This implies an upper limit on the merger rate of subsolar binaries in the range [220-24200]  Gpc^{-3} yr^{-1}, depending on the chirp mass of the binary. We use this upper limit to derive astrophysical constraints on two phenomenological models that could produce subsolar-mass compact objects. One is an isotropic distribution of equal-mass primordial black holes. Using this model, we find that the fraction of dark matter in primordial black holes in the mass range 0.2  M_{⊙}<m_{PBH}<1.0  M_{⊙} is f_{PBH}≡Ω_{PBH}/Ω_{DM}≲6%. This improves existing constraints on primordial black hole abundance by a factor of ∼3. The other is a dissipative dark matter model, in which fermionic dark matter can collapse and form black holes. The upper limit on the fraction of dark matter black holes depends on the minimum mass of the black holes that can be formed: the most constraining result is obtained at M_{min}=1  M_{⊙}, where f_{DBH}≡Ω_{DBH}/Ω_{DM}≲0.003%. These are the first constraints placed on dissipative dark models by subsolar-mass analyses.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Quantum Backaction on kg-Scale Mirrors: Observation of Radiation Pressure Noise in the Advanced Virgo Detector

The quantum radiation pressure and the quantum shot noise in laser-interferometric gravitational wave detectors constitute a macroscopic manifestation of the Heisenberg inequality. If quantum shot noise can be easily observed, the observation of quantum radiation pressure noise has been elusive, so far, due to the technical noise competing with quantum effects. Here, we discuss the evidence of quantum radiation pressure noise in the Advanced Virgo gravitational wave detector. In our experiment, we inject squeezed vacuum states of light into the interferometer in order to manipulate the quantum backaction on the 42 kg mirrors and observe the corresponding quantum noise driven displacement at frequencies between 30 and 70 Hz. The experimental data, obtained in various interferometer configurations, is tested against the Advanced Virgo detector quantum noise model which confirmed the measured magnitude of quantum radiation pressure noise.

GW190521: A Binary Black Hole Merger with a Total Mass of 150 M_{⊙}

On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85_{-14}^{+21}  M_{⊙} and 66_{-18}^{+17}  M_{⊙} (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65  M_{⊙}. We calculate the mass of the remnant to be 142_{-16}^{+28}  M_{⊙}, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3_{-2.6}^{+2.4}  Gpc, corresponding to a redshift of 0.82_{-0.34}^{+0.28}. The inferred rate of mergers similar to GW190521 is 0.13_{-0.11}^{+0.30}  Gpc^{-3} yr^{-1}.

Increasing the Astrophysical Reach of the Advanced Virgo Detector via the Application of Squeezed Vacuum States of Light

Current interferometric gravitational-wave detectors are limited by quantum noise over a wide range of their measurement bandwidth. One method to overcome the quantum limit is the injection of squeezed vacuum states of light into the interferometer's dark port. Here, we report on the successful application of this quantum technology to improve the shot noise limited sensitivity of the Advanced Virgo gravitational-wave detector. A sensitivity enhancement of up to 3.2±0.1  dB beyond the shot noise limit is achieved. This nonclassical improvement corresponds to a 5%-8% increase of the binary neutron star horizon. The squeezing injection was fully automated and over the first 5 months of the third joint LIGO-Virgo observation run O3 squeezing was applied for more than 99% of the science time. During this period several gravitational-wave candidates have been recorded.

[Unusual cause of Takotsubo cardiomyopathy after pacemaker implantation]

Since its first description in Japan in 1990, Takotsubo (stress) cardiomyopathy has gained worldwide recognition. The disease is characterized by transient systolic and diastolic left ventricular dysfunction with a variety of wall-motion abnormalities. She predominantly affects elderly women and she is often preceded by an emotional or physical trigger. In the acute phase, the clinical presentation, electrocardiographic findings and biomarker profiles are often similar to those of an acute coronary syndrome. Although, the cause of Takotsubo cardiomyopathy remains unknown, the role of the brain-heart axis in the pathogenesis of the disease has been described. The potential role of catecholamine excess in the pathogenesis of Takotsubo cardiomyopathy has been long debated, and as such beta-blockers have been proposed as a therapeutic strategy. Currently, the treatment is not codified and it adapts according to clinical symptomatology. It seems difficult to summarize all the factors to provoque the cardiomyopathy, we describe a case of Takotsubo after a pacemaker (PM) implantation and to give a recent progress on this heart disease.

[Coronary artery fistulas, a current problem: Clinical and therapeutic considerations]

The coronary fistula is a link between one or more of the coronary arteries and cardiac cavity or great vessel. The exact occurrence is unknown. The majority of these fistulas are congenital in origin. However, they may occasionally be detected after cardiac surgery. For a long time, fistulas are asymptomatic, especially if they are small; the frequency of the symptoms and especially the complications rise with age. The potential complications are: cardiac failure, endocarditis, endarteritis, atrial fibrillation, ventricular arrhythmias, rupture, and thrombosis. The main differential diagnosis is patent arterial duct, while other congenital arteriovenous shunts need to be excluded. Even though echocardiography Doppler can help to differentiate shunts, the coronary angiography remains the main diagnostic tool for the description of the anatomy. For a long time, the surgery was the only therapeutic means, up till now, percutaneous occlusion is the first line therapy of coronary fistulas and that the different devices can be tailored to meet different anatomic and functional characteristics.

[Measurement of coronary flow and flow reserve with transthoracic echocardiography: an old concept, a new tool, a lot of applications]

Non invasive evaluation of coronary flow and flow reserve by using transthoracic echocardiography is a promising method for evaluating coronary disease. Left anterior descending and right posterior descending coronary flow are accessible in the majority of patients. This technique is useful in various settings: detection of coronary artery stenosis, coronary occlusion, follow up after percutaneous coronary intervention, evaluation of the significance of coronary stenosis of intermediate severity, evaluation of the microcirculation, study of reperfusion and no reflow in the acute phase of myocardial infarction, evaluation of bypass grafts, improvement of the diagnostic accuracy during stress echocardiography. After a period of training, it's possible to change an old concept, formerly not easily accessible in clinical practice, into a useful and modern tool for evaluating coronary artery disease.

[Dyspnea of effort with an unusual cause: diagnostic significance of stress echocardiography]

Left intra ventricular obstruction occurring during doubutamine stress echography is not exceptional but its clinical significance is controversial, notably due to the non-reproducibility of such a phenomenon during physical exercise in a certain number of patients. Moreover, in the studies which demonstrate a link between symptoms of effort and left intra ventricular obstruction during dobutamine echography, an echography with effort was not systematically performed in order to confirm this relationship. We describe the case of two patients, aged 50 and 62 years respectively, with no notable cardiovascular past history except hypertension, who had dyspnoea of effort in the absence of underlying cardiopathy in resting conditions. Dobutamine stress echography provoked a systolic anterior movement of the mitral valve (SAM) responsible for mitral insufficiency and significant left intra ventricular obstruction (maximum gradient of 77 mmHg for one, 130 mmHg for the other), with reproduction of spontaneous symptoms, in the absence of myocardial ischaemia. An effort echography performed several weeks later confirmed these data, even though a sublingual trinitrate (0.3 mg) test was without effect. In the absence of underlying hypertrophic cardiomyopathy the SAM (with left intra ventricular obstruction and mitral insufficiency) occurring during dobutamine stress echography could have clinical significance in selected cases, notably in hypertensive patients with effort intolerance who have normal systolic and diastolic function in the resting state, and absence of myocardial ischaemia during stress, as illustrated in our two observations. The therapeutic implications are clear, with patients like this successfully treated with beta-blockers.

Two different transduction pathways are activated by C3a and C5a anaphylatoxins on astrocytes

C3a and C5a anaphylatoxins are two proinflammatory peptides generated during complement system activation. C3a and C5a exert several biological activities through binding to their specific receptors, named C3aR and C5aR, respectively. We have previously shown that C3aR and C5aR are constitutively expressed by astrocytes, a cell type that actively participates in inflammatory events in the central nervous system. In this article, we focus on the transduction signal pathways activated by these two receptors on astrocytes. We show that the stimulation of C3aR or C5aR results in the activation of the mitogen activated protein kinase pathway by phosphorylation of the p44 and p42 kinases. On the contrary, the binding of C3a or C5a to their receptors on astrocytes decreases the production of cAMP, revealing an inhibition of the adenylyl cyclase pathway. Stimulation of C3aR and C5aR induces an increase in intracellular calcium concentration, arising from the opening of intracellular calcium channels. The observed calcium wave results from the activation of the phospholipase C pathway. Taken together, our results suggest that the binding of C3a or C5a to their receptors on astrocytes would be of functional importance since it induces the activation of two important transduction pathways leading to several cellular events such as neurotrophin and cytokine production.

[Lyme disease presenting as infarction pain. A case report]

Lyme's disease is a multi-system condition due to infection with a spirochete (Borrelia Burgdorferi), transmitted by a tick. Cardiac involvement, which is not systematic, usually presents with transient atrioventricular block of varying degree. The authors describe an unusual presentation of the cardiac involvement of Lyme's disease with chest pain resembling an acute coronary syndrome in a 32 year old man. The characteristic skin lesion (erythema migrans), the positivity of IgM serology, the myocardial scintigraphic results and the negativity of the work-up of other causes of this pain led to a diagnosis of myocarditis, the outcome of which was favourable with treatment by amoxycillin (3 g/day, orally).

Cyclo-oxygenase and lipoxygenase pathways in mast cell dependent-neurogenic inflammation induced by electrical stimulation of the rat saphenous nerve

1. We investigated the role of arachidonic acid metabolism and assessed the participation of mast cells and leukocytes in neurogenic inflammation in rat paw skin. We compared the effect of lipoxygenase (LOX) and cyclo-oxygenase (COX) inhibitors on oedema induced by saphenous nerve stimulation, substance P (SP), and compound 48/80. 2. Intravenous (i.v.) pre-treatment with a dual COX/LOX inhibitor (RWJ 63556), a dual LOX inhibitor/cysteinyl-leukotriene (CysLt) receptor antagonist (Rev 5901), a LOX inhibitor (AA 861), a five-lipoxygenase activating factor (FLAP) inhibitor (MK 886), or a glutathione S-transferase inhibitor (ethacrynic acid) significantly inhibited (40 to 60%) the development of neurogenic oedema, but did not affect cutaneous blood flow. Intradermal (i.d.) injection of LOX inhibitors reduced SP-induced oedema (up to 50% for RWJ 63556 and MK 886), whereas ethacrynic acid had a potentiating effect. 3. Indomethacin and rofecoxib, a highly selective COX-2 inhibitor, did not affect neurogenic and SP-induced oedema. Surprisingly, the structurally related COX-2 inhibitors, NS 398 and nimesulide, significantly reduced both neurogenic and SP-induced oedema (70% and 42% for neurogenic oedema, respectively; 49% and 46% for SP-induced oedema, respectively). 4. COX-2 mRNA was undetectable in saphenous nerves and paw skin biopsy samples, before and after saphenous nerve stimulation. 5. A mast cell stabilizer, cromolyn, and a H(1) receptor antagonist, mepyramine, significantly inhibited neurogenic (51% and 43%, respectively) and SP-induced oedema (67% and 63%, respectively). 6. The co-injection of LOX inhibitors and compound 48/80 did not alter the effects of compound 48/80. Conversely, ethacrynic acid had a significant potentiating effect. The pharmacological profile of the effect of COX inhibitors on compound 48/80-induced oedema was similar to that of neurogenic and SP-induced oedema. 7. The polysaccharide, fucoidan (an inhibitor of leukocyte rolling) did not affect neurogenic or SP-induced oedema. 8. Thus, (i) SP-induced leukotriene synthesis is involved in the development of neurogenic oedema in rat paw skin; (ii) this leukotriene-mediated plasma extravasation might be independent of mast cell activation and/or of the adhesion of leukocytes to the endothelium; (iii) COX did not appear to play a significant role in this process.

Expression of cytokines by human astrocytomas following stimulation by C3a and C5a anaphylatoxins: specific increase in interleukin-6 mRNA expression

C3a and C5a anaphylatoxins are two proinflammatory peptides generated during complement activation that act through distinct Gi protein-coupled receptors named C3aR and C5aR, respectively. We have demonstrated previously that human astrocytes expressed C3aR and C5aR constitutively and were able to produce a functional complement. In this study, we examined the effect of an anaphylatoxin stimulation on cytokine expression by human astrocyte cell lines. Interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha, and transforming growth factor-beta mRNA expression was studied by quantitative RT-PCR. Whereas IL-1beta, tumor necrosis factor-alpha, and transforming growth factor-beta mRNA levels remained unchanged, stimulation of astrocytoma cells (T98G, CB193, U118MG) by C3a, C5a, and peptidic C3aR and C5aR agonists induced an increase in the IL-6 mRNA level. The amount of IL-6 was markedly increased at 3 and 6 h and returned to the basal level at 9 h of stimulation. This response was specific, because pretreatment of cells with pertussis toxin or with polyclonal anti-C3aR or anti-C5aR antibodies completely blocked the IL-6 mRNA increase. The IL-6 response was also investigated at the protein level, but IL-6 protein was detected neither in cell lysates nor in supernatants of stimulated cells. The anaphylatoxin-mediated transcriptional activation of IL-6 gene suggests that C3a and C5a could play a role in priming glial cells during the inflammatory process in the brain.

Expression of a functional anaphylatoxin C3a receptor by astrocytes

Human astrocyte cell lines reportedly contain a specific receptor for the complement anaphylatoxin C3a based on ligand-binding studies, functional responses, and RNA analysis by RT-PCR. Uptake of 125I-C3a by astrocytes was specific and reversible. Scatchard analysis indicated the presence of two classes of binding sites. High-affinity binding sites were abundantly expressed (20,000-80,000 sites per cell) with an estimated K(D) of 1-2 nM. Low-affinity binding sites with a K(D) of 209 nM were largely expressed (n > or = 4 x 10(6) sites per cell) and probably did not reflect a receptor-mediated binding, but rather an ionic interaction between C3a and the membrane. Analysis of astrocyte mRNA by RT-PCR with three different sets of primers covering 60% of the C3a receptor (C3aR) mRNA sequence indicated that glial C3aR was identical to the leukocytic one. Western blot analysis using a specific anti-C3aR evidenced a C3aR with a molecular mass of 60,000 Da. C3a and a superagonist peptide, E7, induced a transient increase of intracellular [Ca2+] in primary culture of astrocytes. Treatment of the ligands by carboxypeptidase B to eliminate the C-terminus Arg considerably decreased the [Ca2+] response. Moreover, flow cytometry experiments demonstrated the expression of C3aR on normal rat astrocyte membrane. This report brings new insight for the role of the complement system in the brain inflammation response.

The receptor for complement anaphylatoxin C3a is expressed by myeloid cells and nonmyeloid cells in inflamed human central nervous system: analysis in multiple sclerosis and bacterial meningitis

The complement anaphylatoxins C5a and C3a are released at the inflammatory site, where they contribute to the recruitment and activation of leukocytes and the activation of resident cells. The distribution of the receptor for C5a (C5aR) has been well studied; however, the receptor for C3a (C3aR) has only recently been cloned, and its distribution is uncharacterized. Using a specific affinity-purified anti-C3aR peptide Ab and oligonucleotides for reverse transcriptase-PCR analysis, C3aR expression was characterized in vitro on myeloid and nonmyeloid cells and in vivo in the brain. C3aR was expressed by adult astrocytes, astrocyte cell lines, monocyte lines THP1 and U937, neutrophils, and monocytes, but not by K562 or Ramos. C3aR staining was confirmed by flow cytometry, confocal imaging, and electron microscopy analysis. A 65-kDa protein was immunoprecipitated by the anti-C3aR from astrocyte and monocyte cell lysates. Our results at the protein level were confirmed at the mRNA level. Using reverse transcriptase-PCR, Southern blot, and sequencing we found that C3aR mRNA was expressed by fetal astrocytes, astrocyte cell lines, and THP1, but not by K562 or Ramos. The astrocyte C3aR cDNA was identical with the reported C3aR cDNA. C3aR expression was not detected in normal brain sections. However, a strong C3aR staining was evident in areas of inflammation in multiple sclerosis and bacterial meningitis. In meningitis, C3aR was abundantly expressed by reactive astrocytes, microglia, and infiltrating cells (macrophages and neutrophils). In multiple sclerosis, infiltrating lymphocytes did not express C3aR, but a strong staining was detected on smooth muscle cells (pericytes) surrounding blood vessels.

Characterization of rat C5a anaphylatoxin receptor (C5aR): cloning of rat C5aR cDNA and study of C5aR expression by rat astrocytes

Complement system activation within the central nervous system (CNS) is involved in demyelinating and neurodegenerative disorders, but the role of complement in the pathogenic process or in the repair remains unclear. Besides the direct lytic effects of complement on target cells (oligodendrocytes or neurons), complement can exert other functions through interaction of complement fragments with specific receptors. The C5a anaphylatoxin, an inflammatory peptide which is formed during complement activation, might play a role in the CNS pathogenesis, and activation and recruitment of glial cells by binding to its receptor (C5aR) on CNS cells. Using degenerate primers corresponding to homologous regions between human and mouse C5aR cDNAs, we have cloned a rat C5aR cDNA probe from rat monocytes RNAs after RT-PCR experiment. The rat C5aR probe isolated by this procedure allowed us to clone the rat C5aR cDNA-coding sequence using a library screening cloning strategy. This probe was also used to study the expression of the C5aR mRNA in the rat CNS. Northern blotting and RT-PCR experiments demonstrated the constitutive expression of C5aR mRNA in brain, spleen, kidney and lung. This transcript was also observed in primary culture of rat astrocytes. Microfluorimetry experiments demonstrated that C5aR expressed by astrocytes in culture is functional since the addition of C5a induced a dose-dependent increase of intracellular calcium concentration. The expression of the C5aR by astrocytes suggests new roles for the C5a anaphylatoxin in reactive astrogliosis to CNS injuries.

Physiological and immunopathological consequences of active immunization of spontaneously hypertensive and normotensive rats against murine renin

Spontaneously hypertensive Okamoto-strain rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were actively immunized with mouse renin to investigate the effect on blood pressure of blocking the renin-angiotensinogen reaction. Ten male SHR and 10 male WKY rats were immunized with purified mouse submandibular gland renin. Control rats were immunized with bovine serum albumin. Antirenin antibodies were produced by both SHR and WKY rats, but renin-immunized SHR had higher titers of circulating renin antibodies after three injections. The increase in renin antibody in renin-immunized SHR was associated with a significant drop in blood pressure (tail-cuff method) that became similar to that of the WKY control rats after four injections. The blockade by antirenin immunoglobulins of the renin-angiotensinogen reaction also decreased the blood pressure of normotensive rats. Perfusion of renin-immunized rats with mouse submandibular renin (10 micrograms) in vivo caused no increase in blood pressure. Perfusion of renin-immunized, salt-depleted SHR with converting enzyme inhibitor caused no further decrease in blood pressure but significantly decreased blood pressure in salt-depleted control rats. The presence of circulating renin antibodies was associated with low plasma renin activity (0.31 +/- 0.23 ng angiotensin I [Ang I]/ml/hr). Plasma renin activity was unchanged in control animals (13.1 +/- 3.9 ng Ang I/ml/hr in control SHR, 13.9 +/- 3.2 ng Ang I/ml/hr in control WKY rats). Renin antibody-rich serum produced a dose-dependent inhibition of rat renin enzymatic activity in vitro. The chronic blockade of the renin-angiotensinogen reaction in renin-immunized SHR produced an almost-complete disappearance of Ang II (0.8 %/- 7 fmol/ml; control SHR, 30.6 +/- 15.7 fmol/ml) and a 50% reduction in urinary aldosterone. Renin immunization was never associated with a detectable loss of sodium after either 10 or 24 weeks. The glomerular filtration rate was not decreased 10 weeks after renin immunization, whereas blood pressure was significantly decreased, plasma renin activity was blocked, and renal plasma flow was increased. The ratio of left ventricular weight to body weight after 24 weeks was significantly below control levels in renin-immunized WKY rats and SHR. Histological examination of the kidney of renin-immunized SHR showed a chronic autoimmune interstitial nephritis characterized by the presence of immunoglobulins, mononuclear cell infiltration, and fibrosis around the juxtaglomerular apparatus. These experiments demonstrate that chronic specific blockade of renin decreases blood pressure in a genetic model of hypertension in which the renin-angiotensin system is not directly involved.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunological approach to blockade of the renin-substrate reaction

To block the renin-substrate reaction by immunological tools is a long-standing dream. Since 1951 active immunization and the passive transfer of antirenin antisera have been successfully carried out in different species and in different experimental models of hypertension and normotension. These studies indicated that renin is a powerful immunogenic protein, capable of breaking down self-tolerance in different species. In this initial period the most significant results were obtained with hog renin. Passive transfer of antisera raised against hog renin or active immunization with hog renin was able to decrease blood pressure in renovascular or essential hypertension in dogs. Renin was semipurified and injected without adjuvant, however, since there was no method for determining plasma renin activity. Recently, complete purification of murine and human renin has allowed an extension of this approach, using the passive transfer of antirenin polyclonal antisera or monoclonal antibodies. Active immunization against pure human renin was successful in normotensive marmosets. This immunization with a nearly homologous renin in a primate model induced a significant decrease in blood pressure, associated with a complete disappearance of plasma renin activity. Unfortunately this powerful immunization was associated with an autoimmune disease that is specific for the kidney, related to self-recognition of the production site of renin by antibodies and lymphocytes. Similar results were reported with the use of mouse submandibular gland renin as an immunogen in spontaneously hypertensive rats (SHR). This manipulation decreased blood pressure in SHR to a level near that of normotensive Wistar-Kyoto control rats. However, again the animals showed a severe autoimmune disease of the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunologic approaches to blockade of the renin-angiotensin system: a review

Several immunologic approaches to blockade of the renin-angiotensin system (RAS) have been reported, involving most of the proteins and peptides of the biochemical cascade: renin, substrate, angiotensins, and converting enzyme. None as yet has involved blockade of angiotensin II receptors. Earlier and more recent studies used passive transfer of heterologous antibodies or active immunization against RAS proteins and peptides. Passive transfers have been performed with both polyclonal antibodies and now with specific monoclonal immunoglobulins. The latter are better defined in affinity, quantity, and capacity to bind and thus inhibit the biologic activity of the antigen. Active immunization produced long-term blockade of part or all of the biologic activity of the system. The immunopathologic consequences of the use of antibodies raised against a self-antigen could be of interest in defining the predominant site of storage and secretion of the relevant protein and hence the respective roles of different tissues in the production of specific proteins in, for example, the vascular pulmonary bed for converting enzyme and renal arterial tree for renin. In all cases immunologic methods offer in vivo experimental models of short- or long-term RAS blockade that could be compared with pharmacologic methods, such as converting-enzyme inhibition, angiotensin II antagonists, and renin inhibitors.

[Immunologic approach of the blockage of the renin angiotensin system in vivo]

To block the renin-angiotensin system by antibodies directed against renin or angiotensins is an old and recent goal. This goal can be attained by passive transfer of antibodies or by active immunization against the different molecules of the system. Only passive transfer of polyclonal antibodies directed against the native substrate (angiotensinogen) has been performed in rats. This acute blockade of angiotensinogen substrate availability decrease blood pressure about 30 mmHg in salt depleted rats. Passive transfer of anti-converting enzyme immunoglobulins has been already performed in rabbit and rat. It induced an immunoallergic reaction in the pulmonary capillary bed. Immunization against angiotensin II has been a powerful tool in the exploration of the role of the renin angiotensin system in hypertension. Passive and active immunization have been performed in different species: rabbit, rat. The majority of the results concerning the decrease in blood pressure was negative. However, some works reported positive results which could be related to the high affinity of antibodies for angiotensins. Passive and active immunizations against renin were also performed in different species: dog, pig, rat, rabbit, primates. The majority of the results concerning the decrease of blood pressure were positive, if species specificity of renin was taken into account. Recently passive transfer of polyclonal and monoclonal antibodies, directed against human renin have been performed in normotensive and hypertensive primates, demonstrating an acute fall in blood pressure comparable to that observed with converting enzyme inhibitors. Active immunization against human renin has also been performed in primates; and the chronic blockade of the renin-substrate reaction obtained in this way was associated with a significant decrease in blood pressure, aldosterone secretion and a disappearance of plasma renin activity. Unfortunately, such an active immunization was associated with an organ specific autoimmune disease within the kidney. In conclusion, passive and active immunization against the different proteins and peptides of the system offers specific models of blockade which can be compared with synthetic inhibitors of renin, converting enzyme and angiotensins. Therapeutic application of this immunological approach necessitates the verification of the total absence of autoimmune disease.