P-677 Increasing the efficacy of FSH with a potentiating monoclonal antibody

Study question

Can we potentiate FSH activity with antibodies to improve ovarian stimulation?

Summary answer

IGYXOS developed a potentiating monoclonal antibody that improves FSH potency and efficacy in vitro and in vivo as demonstrated in different animal models.

What is known already

FSH plays a key role in reproduction. For a controlled ovarian stimulation in IVF cycles, FSH-containing preparations are injected to patients in order to obtain mature and fertilizable oocytes. However, the efficacy of these treatments is frequently limited and sometimes several attempts are needed before reaching a pregnancy and a live birth.

It was previously demonstrated that breeding animals treated with gonadotropins could develop anti-gonadotropin antibodies that enhance their bioactivity instead of inhibiting it. These females had a high kidding rate and sometimes were hyperprolific.

Study design, size, duration

IGYXOS developed a monoclonal antibody (mAb) directed against human FSH. The mAb CF12 was selected based on its ability to increase FSH activity in vitro and in vivo in female rat. Its potentiating activity was tested on different human FSH preparations. The potentiating effect of CF12 was further investigated in ewe treated with mAb alone or FSH alone.

Participants/materials, setting, methods

CF12 was tested in vitro on HEK 293 cells expressing the human FSH receptor and a cell reporter system for cAMP. In vivo, the mAb was tested according to the Steelman and Pohley protocol on different human FSH preparations. Its potentiating effect was also investigated in an ovulation induction protocol on mature ewes.

Main results and the role of chance

In HEK 293 cells expressing the human FSH receptor, CF12 combined to FSH improved both the potency (EC50) and the efficacy (Emax) of FSH by increasing the cyclic AMP production at all tested FSH concentrations. The potentiating activity was confirmed in immature female rats treated with hCG+FSH alone or combined to mAb, twice a day, during 3 days. The animals were sacrificed the fourth day of treatment and the weight of the ovaries was compared. Ovaries weight was significantly increased in the group treated with hCG/FSH+CF12 compared to hCG/FSH only.

To further analyze the effect of CF12 on ovulation induction, it was investigated in ewe as a breeding animal model. Animals were first synchronized with a progestagen and then treated either with FSH alone or with CF12 alone. The number of ovulations was investigated by endoscopy by counting corpora lutea and the progesterone secretion was measured over the luteal cycle. All females treated with CF12 ovulated (100%) by contrast 40% ovulated with FSH treatment. The ovulation rate was 1.8 fold higher in group treated with CF12 compared to FSH group. Moreover, progesterone secretion during luteal phase was increased in animals treated with CF12 suggesting a better quality of corpora lutea.

Limitations, reasons for caution

After several proofs of concept obtained in different animal models, the compound is currently in the humanization phase before starting the CMC process and then preclinical studies.

Wider implications of the findings

The potentiating antibody CF12 is a new concept. It represents an interesting strategy in reproductive health, particularly to improve the IVF outcome. CF12 is currently developed for human application by our company and could be a game changer in the field of ovarian stimulation by enhancing the efficacy of FSH.

Trial registration number

not applicable

Follow-Up and Management of Chronic Rhinosinusitis in Adults with Primary Ciliary Dyskinesia: Review and Experience of Our Reference Centers

Chronic rhinosinusitis is the foremost manifestation in adult patients with primary ciliary dyskinesia (PCD). We present a retrospective series of 41 adult patients with a confirmed diagnosis of PCD followed in our reference centers. As part of the diagnostic work up in our centers, sinus computed tomography scans (CTs) are systematically performed. All patients also undergo a sampling of purulent secretions sampled from the middle meatus under endoscopic view for bacteriological analysis. In our series, CT opacities were consistent in all the patients, as well as mainly partial and located in ethmoid cells (100% of patients) and in maxillary sinuses (85.4% of patients), and stayed stable over time. In the 31 patients who had purulent secretions, bacteriological culture showed at least one bacterium in 83.9% (n = 26). There was no significant difference in positive cultures for Pseudomonas aeruginosa in patients >40 years old versus those <40 (p = 0.17; Fisher). Surgical management was performed in only 19% of patients in order to improve sinonasal mechanical drainage. Our data support the hypothesis that the sinuses can be considered as a bacterial reservoir. From this retrospective study, we have introduced several changes into our routine clinical practice in our reference centers. Based on our analyses, medical and surgical treatments benefit from incorporating bacteriological information and sinonasal symptoms much more than CT scan evaluation alone. All patients now undergo systematically an annual simultaneous bacteriological sampling of the middle meatus and sputum to follow the relationship between ENT and lung disease and to help to antibiotic therapy strategy.

Modulation of Gonadotropins Activity by Antibodies

Gonadotropins are essential for reproduction control in humans as well as in animals. They are widely used all over the world for ovarian stimulation in women, spermatogenesis stimulation in men, and ovulation induction and superovulation in animals. Despite the availability of many different preparations, all are made of the native hormones. Having different ligands with a wide activity range for a given receptor helps better understand its molecular and cellular signaling mechanisms as well as its physiological functions, and thus helps the development of more specific and adapted medicines. One way to control the gonadotropins' activity could be the use of modulating antibodies. Antibodies are powerful tools that were largely used to decipher gonadotropins' actions and they have shown their utility as therapeutics in several other indications such as cancer. In this review, we summarize the inhibitory and potentiating antibodies to gonadotropins, and their potential therapeutic applications.

An in situ atomic force microscope for normal-incidence nanofocus X-ray experiments

A compact high-speed X-ray atomic force microscope has been developed for in situ use in normal-incidence X-ray experiments on synchrotron beamlines, allowing for simultaneous characterization of samples in direct space with nanometric lateral resolution while employing nanofocused X-ray beams. In the present work the instrument is used to observe radiation damage effects produced by an intense X-ray nanobeam on a semiconducting organic thin film. The formation of micrometric holes induced by the beam occurring on a timescale of seconds is characterized.

150 USING A LUTEINIZING HORMONE SURGE DETECTION TEST, PREDI&apos;BOV&reg;, TO OPTIMIZE THE TIME OF ARTIFICIAL INSEMINATION DURING A SUPEROVULATION PROTOCOL IN A HOLSTEIN HEIFERS HERD

Insemination of superovulated bovine donors in due time is of central importance for fertilization and embryo viability. A preliminary test focusing on LH surge detection during superovulation (unpublished datas) indicated that one quarter of the donors present LH surges 12 to 24 h before heat observation (which could correspond, in the case of AI after heat observation, to post ovulation AI). Therefore, it was hypothesised that the average number of embryos per flush could be improved by inseminating donors with early LH surge 12 h after the beginning of the LH peak whenever the heat occurs.In a donor herd station, a trial was performed with 54 Holstein heifers, equipped with Heatime® tags (system detecting the peak activity linked to the heat) collected twice or 3 times after the following superovulation protocol: D-6 to D-11 = reference heat; D0 = input of an implant of norgestomet (Crestar®); D2 8:00 = first FSH (Stimufol®) injection (FSH1); D4 8:00 = cloprostenol (Estrumate®) injection; D4 16:00 = implant removal; D5 8:00 = FSH7 and first LH surge detection test (Predi'Bov®); D5 16:00 = FSH8 and 2nd Predi'Bov® test. Two AI's at interval of 8 to 16h were done (AI's were performed either at 9:00, or between 17:00 and 19:00). For the standard protocol (= STA), thefirst AI occurred after heat observation or activity peak detection by Heatime (whatever the Predi'Bov® test results were). For the adjusted protocol (= ADJ), the first AI occurred from 11 to 16 h after the first positive Predi'Bov® test result or like STA protocol if both results were negative. Heifers followed alternately the 2 protocols, 27 beginning with the ADJ protocol, 27 others with the STA one. LH surge precocity was not repeatable among donors. In the case of an early LH surge detection (one positive Predi'Bov® test), the heat activity peak occurred from 2 to 8 h after the FSH8 for 44% of the flushes, from 8 to 24 h after FSH8 for 54% of the flushes and never for 2% of the flushes. When no early LH surge was observed, the heat activity peak occurred more than 8 h after FSH8 for 78% of the flushes. Interval of heat activity peak-FSH8, IA1-heat activity peak and IA1-early LH surge were highly variable but did not effect the mean number of viable embryos. However, we observed a significant effect (P = 0.04) of the precocity of the heat on the average number of total embryos: 13.8 ± 8.4 v. 11.1 ± 8.1 when the interval heat activity peak-FSH8 had been respectively <8 h or ≥8 h, respecively. Among the 148 collections, 74 were done after the STA protocol, 74 after the ADJ protocol and 70 followed an early LH surge. The adjustment of the AI depending on the detection of an early LH surge (ADJ protocol) had a significant positive (P = 0.04) effect on the mean percentage of viable embryos per flush (52% ± 28 in STA group and 62% ± 31 in ADJ group). Nevertheless, regarding the mean number of viable embryos, this effect failed to reach significance (P = 0.23) (respectively 5.7 ± 5.1 in STA group and 6.7 ± 6.7 in ADJ group). A larger study on more animals is necessary to obtain a significant difference in the number of viable embryos.

Activation of a GPCR leads to eIF4G phosphorylation at the 5' cap and to IRES-dependent translation

The control of mRNA translation has been mainly explored in response to activated tyrosine kinase receptors. In contrast, mechanistic details on the translational machinery are far less available in the case of ligand-bound G protein-coupled receptors (GPCRs). In this study, using the FSH receptor (FSH-R) as a model receptor, we demonstrate that part of the translational regulations occurs by phosphorylation of the translation pre-initiation complex scaffold protein, eukaryotic initiation factor 4G (eIF4G), in HEK293 cells stably expressing the FSH-R. This phosphorylation event occurred when eIF4G was bound to the mRNA 5' cap, and probably involves mammalian target of rapamycin. This regulation might contribute to cap-dependent translation in response to FSH. The cap-binding protein eIF4E also had its phosphorylation level enhanced upon FSH stimulation. We also show that FSH-induced signaling not only led to cap-dependent translation but also to internal ribosome entry site (IRES)-dependent translation of some mRNA. These data add detailed information on the molecular bases underlying the regulation of selective mRNA translation by a GPCR, and a topological model recapitulating these mechanisms is proposed.

153 DETECTING PRE-OVULATORY LUTEINIZING HORMONE PEAKS IN ORDER TO OPTIMIZE THE RATIO OF VIABLE EMBRYOS USING PREDI′BOV®, A NEW ON-FARM OVULATION TEST

The LH peak in cattle is the most precise event for predicting ovulation beginning 24 h later, and thus, AI time. Previous studies demonstrated that embryo production was improved when AI was conducted 12 h before ovulation; that is, 12 h after LH peak. This study aimed to evaluate the benefit of LH peak monitoring with Predi′Bov® (ReproPharm®, Nouzilly, France) following superstimulation in order to optimize numbers of viable embryos (VE). Predi′Bov® is a rapid (40 min) and easy to use on-farm test allowing LH peak detection from a few drops of blood. The test was also used to estimate the variability in the time of the LH peak and onset of oestrus. This study was conducted by the embryo transfer teams of 3 French cooperatives, in collaboration with UNCEIA. Forty heifers in stations (Creavia, Midatest) and 23 cows on farms (GEN′Iatest) were superstimulated by 8 injections IM of Stimufol® or Pluset® (FSH1 to FSH8) over 4 days in 2011–2012. Donor station heifers were treated twice in a Latin square design with a reference protocol where AI was conducted 12 and 24 h after onset of oestrus, and in an experimental protocol where AI was conducted 12 and 24 h after a positive Predi′Bov® test. Semen of different sires was used for both protocols. The Predi′Bov® test was carried out on 3 blood samples (BS1,2,3) collected every 6 h beginning at FSH7 in stations and FSH8 on farms to detect the earliest LH peaks. To determine late LH peaks, Predi′Bov® test was carried out on BS4 collected 24 h after FSH8. Univariate statistical analysis was performed to look at the relationship between qualitative (chi-square) and quantitative (t-test) variables. The difference was considered significant when P < 0.05. The Predi′Bov® test showed that 37.5% (15/40) of LH peaks occurred during the last day of FSH treatment (BS1 or BS2) in stations and 26.1% (6/23) at BS1 on farms. At Creavia station (n = 24), the LH peak was detected anytime from 24 h before to 9 h after the onset of oestrus. In stations, the VE percentage did not differ whether AI was done following oestrus or LH peak detection (63.1% and 61.8% in reference and experimental protocols, respectively). In stations, the VE percentage from 9 females with an LH peak detected at FSH7 (BS1; 41%) in the reference protocol did not differ from the experimental protocol (50%). On farms, the VE percentage was numerically higher but not significant in the experimental protocol (65.4%, n = 16) compared to the reference protocol (47.2%, n = 7). Further investigations are needed, taking into account the effect of collection rank, sire, and female effects, to confirm the trends shown by these results. In conclusion, Predi′Bov® can be used as easily on farms as in stations. Its use allows the detection of animals that have early or late LH peaks, which in turn provides the opportunity of carrying out AI at the optimal time for such females.

[Migration of a ventriculoperitoneal shunt in the liver: A rare complication]

We report on a case of migration inside the liver of the distal end of a ventriculoperitoneal shunt catheter in an adult patient. A simple laparotomy permitted the surgical removal with no haemorrhagic complication. We discuss the other cases reported in the literature and we outline the need to perform an abdominal CT scan in patients carrying a VP shunt with digestive symptoms.

What are the implications of variation in root hair length on tolerance to phosphorus deficiency in combination with water stress in barley (Hordeum vulgare)?

BACKGROUND AND AIMS

Phosphorus commonly limits crop yield and is frequently applied as fertilizer; however, supplies of quality rock phosphate for fertilizer production are diminishing. Plants have evolved many mechanisms to increase their P-fertilizer use efficiency, and an understanding of these traits could result in improved long-term sustainability of agriculture. Here a mutant population is utilized to assess the impact of root hair length on P acquisition and yield under P-deficient conditions alone or when combined with drought.

METHODS

Mutants with various root hair phenotypes were grown in the glasshouse in pots filled with soil representing sufficient and deficient P treatments and, in one experiment, a range of water availability was also imposed. Plants were variously harvested at 7 d, 8 weeks and 14 weeks, and variables including root hair length, rhizosheath weight, biomass, P accumulation and yield were measured.

KEY RESULTS

The results confirmed the robustness of the root hair phenotypes in soils and their relationship to rhizosheath production. The data demonstrated that root hair length is important for shoot P accumulation and biomass, while only the presence of root hairs is critical for yield. Root hair presence was also critical for tolerance to extreme combined P deficit and drought stress, with genotypes with no root hairs suffering extreme growth retardation in comparison with those with root hairs.

CONCLUSIONS

The results suggest that although root hair length is not important for maintaining yield, the presence of root hairs is implicit to sustainable yield of barley under P-deficient conditions and when combined with extreme drought. Root hairs are a trait that should be maintained in future germplasm.

Competing G protein-coupled receptor kinases balance G protein and β-arrestin signaling

The molecular mechanisms and hidden dynamics governing ERK activation by the angiotensin II type 1A receptor are studied and deciphered, revealing a signal balancing mechanism that is found to be relevant to a range of other seven transmembrane receptors.

An ODE-based dynamical model of ERK activation by the prototypical angiotensin II type-1A seven transmembrane receptor has been built and validated.

In order to deal with a limited number of experimental read-outs, unknown parameters have been inferred by simultaneously fitting control and perturbed conditions.

In addition to its well-established function in G-protein uncoupling, G protein-coupled receptor kinase 2 has been shown to exert a strong negative effect on β-arrestin-dependent signaling and by doing so, to balance G-protein and β-arrestin signaling.

This novel function of G protein-coupled receptor kinase 2 has also been evidenced in primary vascular smooth muscle cells naturally expressing the AT_1AR and in HEK293 cells expressing other 7TMRs.

Seven-transmembrane receptors (7TMRs) are involved in nearly all aspects of chemical communications and represent major drug targets. 7TMRs transmit their signals not only via heterotrimeric G proteins but also through β-arrestins, whose recruitment to the activated receptor is regulated by G protein-coupled receptor kinases (GRKs). In this paper, we combined experimental approaches with computational modeling to decipher the molecular mechanisms as well as the hidden dynamics governing extracellular signal-regulated kinase (ERK) activation by the angiotensin II type 1A receptor (AT_1AR) in human embryonic kidney (HEK)293 cells. We built an abstracted ordinary differential equations (ODE)-based model that captured the available knowledge and experimental data. We inferred the unknown parameters by simultaneously fitting experimental data generated in both control and perturbed conditions. We demonstrate that, in addition to its well-established function in the desensitization of G-protein activation, GRK2 exerts a strong negative effect on β-arrestin-dependent signaling through its competition with GRK5 and 6 for receptor phosphorylation. Importantly, we experimentally confirmed the validity of this novel GRK2-dependent mechanism in both primary vascular smooth muscle cells naturally expressing the AT_1AR, and HEK293 cells expressing other 7TMRs.

The dynamics of root meristem distribution in the soil

Plants must develop efficient root architectures to secure access to nutrients and water in soil. This is achieved during plant development through a series of expansion and branching processes, mostly in the proximity of root apical meristems, where the plant senses the environment and explores immediate regions of the soil. We have developed a new approach to study the dynamics of root meristem distribution in soil, using the relationship between the increase in root length density and the root meristem density. Initiated at the seed, the location of root meristems in barley seedlings was shown to propagate, wave-like, through the soil, leaving behind a permanent network of roots for the plant to acquire water and nutrients. Data from observations on barley roots were used to construct mathematical models to describe the density of root meristems in space. These models suggested that the morphology of the waves of meristems was a function of specific root developmental processes. The waves of meristems observed in root systems of barley seedlings exploring the soil might represent a more general and fundamental aspect of plant rooting strategies for securing soil resources.

Syndrome de Fryns. Présentation de 3 nouvelles observations

BACKGROUND

Fryns syndrome is a lethal autosomal recessive syndrome which includes congenital diaphragmatic hernia (CDH), pulmonary hypoplasia, cranio-facial manifestations including a coarse face, a cleft palate / lip and cloudy corneae, distal limb hypoplasia and internal malformations including central nervous system, cardiovascular, gastrointestinal, urogenital and skeletal anomalies.

CASES REPORT

We report on 3 patients with Fryns syndrome in the french Indian Ocean islands (La Réunion and Mayotte islands). Pregnancies were complicated by polyhydramnios. All patients had coarse face, cloudy corneae, cleft lip / palate or high-arched palate, hypoplastic nails and brachytelephalangy. They died in the neonatal period. Two had CDH and 1 did not have a diaphragmatic involvement but a severe respiratory distress syndrome with refractory hypoxemia. Cytogenetic studies of blood lymphocytes and skin fibroblasts were normal.

CONCLUSIONS

Fryns syndrome is the most common multiple congenital anomaly associated with CDH. The diagnosis is strongly suggested when CHD and brachytelephalangy are associated. Phenotypes with CDH similar to Fryns syndrome have been described with cytogenetic aberrations with G-banded chromosome analysis and submicroscopic chromosome deletions detected by high resolution karyotyping or array comparative genomic hybridization (CGH). Exclusion of chromosome aberrations (including isochromosome 12p in skin fibroblasts) is needed prior to making the diagnosis of Fryns syndrome. In sporadic cases, high resolution karyotyping or array CGH should be performed for correct diagnosis and genetic counselling.

A density-based approach for the modelling of root architecture: application to Maritime pine (Pinus pinaster Ait.) root systems

Root morphology influences strongly plant/soil interactions. However, the complexity of root architecture is a major barrier when analysing many phenomena, e.g. anchorage, water or nutrient uptake. Therefore, we have developed a new approach for the representation and modelling of root architecture based on branching density. A general root branching density in a space of finite dimension was used and enabled us to consider various morphological properties. A root system model was then constructed which minimizes the difference between measured and simulated root systems, expressed with functions which map root density in the soil. The model was tested in 2D using data from Maritime pine Pinus pinaster Ait. structural roots as input. We showed that simulated and real root systems had similar root distributions in terms of radial distance, depth, branching angle and branching order. These results indicate that general density functions are not only a powerful basis for constructing models of architecture, but can also be used to represent such structures when considering root/soil interaction. These models are particularly useful in that they provide a local morphological characterization which is aggregated in a given unit of soil volume.

Reproducibility of the respiratory dead space measurements in mechanically ventilated children using the CO2SMO monitor

OBJECTIVES

To assess the reproducibility of respiratory dead space measurements in ventilated children.

DESIGN

Prospective study.

SETTING

University pediatric intensive care unit.

PATIENTS

Thirty-two mechanically ventilated children (0.13-15.4 years) who were clinically stable.

METHODS

The single-breath CO(2) test (SBT-CO(2)) was recorded using the CO(2)SMO Plus from the mean of 30 ventilatory cycles during 1 h (at T0, T15, T30, T45, and T60). Airway dead space was determined automatically (Novametrix Medical Systems, USA), and manually by Bohr- Enghoff equations using data obtained by SBT-CO(2). At the end of the study period, arterial blood gas was sampled in order to calculate alveolar and physiologic dead space. Intrasubject reproducibility of measurements was evaluated by the intraclass correlation coefficient. Two-way analysis of variance was used to evaluate the relationships between time and measurements. The two methods for calculating airway dead space were compared by using two-tailed Student's t-test and Bland-Altman analysis.

RESULTS

Airway dead space measurement had a good reproducibility during the 1-h period, whatever the method used (intraclass correlation coefficient: 0.84 to 0.87). No significant difference was observed with time. Airway dead space values from the SBT-CO(2) method were smaller than those from Bohr-Enghoff equations. Physiologic dead space values from the SBT-CO2 method were similar to those from Bohr-Enghoff equations.

CONCLUSION

The measurement of airway dead space by the CO(2)SMO Plus was reproducible over a 1-h period in children requiring mechanical ventilation, provided ventilatory parameters were constant throughout the study. SBT-CO(2) analysis may provide a bedside non-invasive monitoring of volumetric capnography.

IRAS Is an Anti-Apoptotic Protein

Active cell death, also known as apoptosis, has been implicated in the pathophysiology of diseases such as cancer, heart failure and neurodegenerative disorders. We report the anti-apoptotic function of IRAS, which was previously shown to bind imidazoline ligands. The amino acid sequence of human IRAS (hIRAS) is unrelated to known proteins, except for rat IRAS and a mouse homologue named nischarin, which binds the alpha5 integrin subunit of the fibronectin receptor. When stably transfected into PC12 cells, hIRAS localizes to the cytosol as a 167 kDa immunoreactive protein. Clonal PC12 cell lines expressing hIRAS displayed normal serum growth responses. However, hIRAS expression led to prolonged cell survival against known apoptotic stimuli: serum starvation or thapsigargin or staurosporine treatments. The apoptotic population of hIRAS-expressing cells was significantly reduced, and this protection was achieved by a decrease in caspase-3 activity, phosphatidylserine translocation, and nuclear fragmentation. Similar protective effect was obtained in COS7 cells transiently transfected with hIRAS. A partial activation of the PI3 kinase pathway is possibly implicated in the anti-apoptotic effect of IRAS. Thus, IRAS appears to represent a previously unknown anti-apoptotic protein involved in the regulation of cell survival.

[125I]2-(2-chloro-4-iodo-phenylamino)-5-methyl-pyrroline (LNP 911), a high-affinity radioligand selective for I1 imidazoline receptors

The I1 subtype of imidazoline receptors (I1R) is a plasma membrane protein that is involved in diverse physiological functions. Available radioligands used so far to characterize the I(1)R were able to bind with similar affinities to alpha2-adrenergic receptors (alpha2-ARs) and to I1R. This feature was a major drawback for an adequate characterization of this receptor subtype. New imidazoline analogs were therefore synthesized and the present study describes one of these compounds, 2-(2-chloro-4-iodo-phenylamino)-5-methyl-pyrroline (LNP 911), which was of high affinity and selectivity for the I1R. LNP 911 was radioiodinated and its binding properties characterized in different membrane preparations. Saturation experiments with [125I]LNP 911 revealed a single high affinity binding site in PC-12 cell membranes (K(D) = 1.4 nM; B(max) = 398 fmol/mg protein) with low nonspecific binding. [125I]LNP 911 specific binding was inhibited by various imidazolines and analogs but was insensitive to guanosine-5'-O-(3-thio)triphosphate. The rank order of potency of some competing ligands [LNP 911, PIC, rilmenidine, 4-chloro-2-(imidazolin-2-ylamino)-isoindoline (BDF 6143), lofexidine, and clonidine] was consistent with the definition of [125I]LNP 911 binding sites as I1R. However, other high-affinity I1R ligands (moxonidine, efaroxan, and benazoline) exhibited low affinities for these binding sites in standard binding assays. In contrast, when [125I]LNP 911 was preincubated at 4 degrees C, competition curves of moxonidine became biphasic. In this case, moxonidine exhibited similar high affinities on [125I]LNP 911 binding sites as on I1R defined with [125I]PIC. Moxonidine proved also able to accelerate the dissociation of [125I]LNP 911 from its binding sites. These results suggest the existence of an allosteric modulation at the level of the I1R, which seems to be corroborated by the dose-dependent enhancement by LNP 911 of the agonist effects on the adenylate cyclase pathway associated to I1R. Because [125I]LNP 911 was unable to bind to the I2 binding site and alpha2AR, our data indicate that [125I]LNP 911 is the first highly selective radioiodinated probe for I1R with a nanomolar affinity. This new tool should facilitate the molecular characterization of the I1 imidazoline receptor.

Role of cellular actin in the gene expression and morphogenesis of human respiratory syncytial virus

Cytoskeletal protein actin and nonactin cellular proteins were essential for human respiratory syncytial virus (RSV) gene expression. In vitro, specific antibodies against actin inhibited RSV transcription, whereas antibodies against other cytoskeletal proteins had little or no effect. Affinity purified cellular actin or bacterially expressed recombinant actin activated RSV transcription. However, optimal transcription required additional cellular protein(s) that appeared to function as accessory factor(s) for actin. In the absence of actin, these proteins did not activate viral transcription. Purified viral nucleocapsids contained actin, but no cytokeratin, tubulin, or vimentin. Cytochalasin D or DNasel--agents that destabilize actin polymers--had little effect on RSV transcription. RSV infection itself seemed to alter the structure of the cellular actin filaments. Treatment of infected cells with cytochalasin D produced a more severe disruption of the filaments and drastically reduced the production of infectious virus particles but still had little effect on intracellular synthesis of viral macromolecules. Thus actin seems to serve a dual role in RSV life cycle: its monomeric form as well as polymeric form activate viral transcription, while only the microfilament form may take part in viral morphogenesis and/or budding.

Cefotetan: comparative study in vitro against 226 Gram-negative clinical isolates

The activity in vitro of the new cephamycin, cefotetan, was compared with that of cephalothin, cefoxitin, cefuroxime and cefotaxime against 226 recently isolated Gram-negative pathogens (207 Enterobacteriaceae and 19 Acinetobacter). Cefotetan was consistently more potent than cephalothin, cefoxitin and cefuroxime. Cefotaxime and cefotetan were essentially similar in activity against the Enterobacteriaceae with the singular exception of Enterobacter spp. which were markedly more susceptible to the former drug. None of the five agents was especially active against acinetobacter but cefotaxime was the best. Limited tests of bactericidal activity showed that the MBC differed from the MIC by a factor of 4 at most. Increasing the inoculum tested from 10(2) to 10(8) per ml had little adverse effect on the MIC of cefotetan. If the recommendations of the National Committee for Clinical Laboratory Standards for susceptibility to cephalosporins are applicable to cefotetan and the breakpoint criteria of less than or equal to 10 mg/l (sensitive) and greater than or equal to 32 mg/l (resistant) are acceptable, then only a few of the Enterobacteriaceae in this study were resistant. These resistant organisms were amongst Enterobacter spp. and Citrobacter spp.

[Dibekacin: diffusion in bronchial mucus]

The study of the bronchial concentration of dibekacin has shown a different degree of activity than that of gentamicin. This activity resembles that of amikacin with a three hour time lag from the appearance of the bronchial peak in relationship to the serum peak. In addition there seems to be a special passage mechanism for the antibiotic from the blood into the bronchial secretions since we observed an increase in the mucus/serum ratio through time.