Ifenprodil and SL 82.0715 as cerebral anti-ischemic agents. II. Evidence for N-methyl-D-aspartate receptor antagonist properties

The effects of the anti-ischemic agents ifenprodil and its derivative SL 82.0715 ((+/-)-alpha-(4-chlorophenyl)-4-[(4-fluorophenyl) methyl]-1-piperidineethanol] have been analyzed in a number of models indicative of N-methyl-D-aspartate (NMDA) antagonistic potential in vitro and in vivo. Ifenprodil and SL 82.0715 potently and noncompetitively antagonize the stimulatory effects of NMDA on cyclic GMP production in immature rat cerebellar slices (IC50 values, 0.4 and 10 microM, respectively), as well as the NMDA-evoked [3H]acetylcholine release in adult rat striatal slices (IC50 values, 1.6 and 6.6 microM, respectively). Ifenprodil is 10 times more potent than (+/-)3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) but less active than the reference noncompetitive NMDA channel blockers [MK 801, ((+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10-imine ], phencyclidine and 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP)] in these models. Ifenprodil and SL 82.0715 partially displace (maximal displacement 40-50% at 10 microM) the NMDA receptor ligand [3H]CPP from its binding site to rat brain membranes (IC50 values, 0.1 and 0.3 microM, respectively) in a noncompetitive manner; in the micromolar range the two agents also partially displace the NMDA channel ligand [3H]TCP from its binding site to rat brain membranes, and noncompetitively antagonize the L-glutamate-induced increase in [3H]TCP binding. Ifenprodil (0.01-1 microM) partially antagonizes the depolarizing effects of NMDA on the immature rat hemisected spinal cord in vitro. In mouse cultured spinal cord neurons, ifenprodil dose-dependently antagonizes the depolarizing effects of micropressure applied NMDA. Inhibition of the effects of NMDA in this model by ifenprodil and SL 82.0715 is noncompetitive. In vivo and after systemic i.p. administration, ifenprodil and SL 82.0715 antagonize the stimulatory effects of intrastriatally dialyzed NMDA on striatal dopamine release in rats (ID50 values, 0.9 and 0.3 mg/kg, respectively), and block the harmaline-evoked increase in cerebellar cyclic GMP production in mice (ID50 values, 3 and 4 mg/kg, respectively). These results indicate that ifenprodil is a noncompetitive NMDA antagonist which has a mechanism of action distinct from either the reference competitive NMDA receptor antagonists (CPP and 2-amino-5-phosphonovalerate) or the noncompetitive NMDA channel blockers (phencyclidine, TCP and MK 801). The potent NMDA antagonistic effects of the ifenprodil class of compounds are likely to be related to the demonstrated anti-ischemic potential of these compounds.

Electrophysiology and ultrastructure of mouse hypothalamic neurons in culture: a correlative analysis during development

The development of the electrical activity of hypothalamic neurons in dissociated cell cultures obtained from 14 day old mice foetuses was studied using patch extracellular and intracellular recording techniques. Electrophysiological data were compared with morphological observations obtained by electron microscopy. During patch recording, excitability of the cells was tested by the application of a 40 mM KCl solution. Tetrodotoxin (TTX, 10(-6) M in the delivery pipette) and Co2+ (10(-2) M in the delivery pipette) were applied to the recorded cell by pressure in order to study the involvement of sodium and calcium currents in the electrical activity during the in vitro development. From the first day of incubation, TTX and Co2+ were able to block reversibly the spontaneous electrical activity. However, only TTX application inhibited action potentials which suggests that calcium currents could be poorly involved in the action potential generation at the beginning of neuronal differentiation. Three different phases were found in the electrophysiological development of hypothalamic neurons in culture. The first phase (between the 1st and the 5th day of incubation) was characterized by an increase in the ratio of the spontaneously active cells (15% at day 1 and 90% at day 5). This increase paralleled the increase of the ratio of excitable cells. During this period no post-synaptic activity was detected. Morphologically, at 36 h, no synaptic contact was observed and growth cones were found to be very primitive. The second phase, between the 6th and the 9th day of culture, was characterized by a decrease in the ratio of spontaneously active cells and by the appearance, in a few cases, of a postsynaptic potential activity. During this phase the majority of the silent cells were excitable. At this stage neurons formed well differentiated neurites and growth cones. Synaptogenesis had already started and several stages of synapse formation could be seen. The third phase of the development, from 10 days of incubation, was characterized by an increase in post synaptic potential activity. During this period, numerous mature synapses could be observed although most of the synaptic contacts were located on neurites. In addition, some synapses were apposed onto degenerated structures. In conclusion, hypothalamic neurons in culture appear to differentiate in 3 steps: a primitive stage during which spontaneous electrical activity and excitability develop without any synaptic contact; a 2nd stage during which synaptic contacts develop, followed by a third stage of synapse maturation where mature synapses are formed whereas transient synapses degenerate.

A study of ionic conductances involved in plateau potential activity in putative vasopressinergic neurons in primary cell culture

Vasopressin neurons in hypothalamic cell culture display regenerative calcium-dependent plateau potentials. The present study was undertaken to investigate the mechanisms underlying their time course and periodicity. Intracellular recordings showed that the duration of the plateaux was controlled by a progressive activation of a voltage- and calcium-dependent potassium conductance, but not by a progressive inactivation of calcium conductances. The refractory period appeared to be due to a calcium-dependent potassium conductance activated by membrane potential depolarization.

Proteoglycan biosynthesis by rabbit articular chondrocytes treated with D-penicillamine

Rabbit articular chondrocytes in confluent monolayer cultures were treated with D-Penicillamine (D-Pen) during 3 or 5 days. The [35S]-sulfate incorporation in neosynthesized proteoglycans was not modified by D-Pen doses ranging from 50 to 800 micrograms/ml. After treatment during 5 days with D-Pen concentrations of 50 or 400 micrograms/ml, the chemical characteristics of proteoglycans from medium and cell-layer were determined. The aggregation capacity of proteoglycans from medium, the monomer molecular size, the glycosaminoglycan chain length and the relative rates of the different glycosaminoglycans (chondroitins, chondroitin 6-sulfate, chondroitin 4-sulfate, hyaluronic acid) remained unchanged. These results suggest that D-Pen does not alter some of the cartilage mechanical properties due to the presence of proteoglycans.

Calcium ionophore and phorbol myristate acetate synergistically inhibited proteoglycan biosynthesis in articular chondrocytes by prostaglandin independent mechanism

In rabbit articular chondrocytes, phorbol myristate acetate (PMA), 1,2-dioctanoyl-sn-glycerol (DG) and calcium ionophore (A23187), reduced the proteoglycan synthesis, in a dose-dependent manner. The combined treatment by PMA and A23187 resulted in an enhanced inhibition of proteoglycan production, indicating a synergistic effect. In presence of PMA or A23187, the release of prostaglandin E2 (PGE2) was dramatically increased. The addition of indomethacin and BW755c to chondrocytes stimulated by PMA or A23187, suppressed the liberation of PGE2, but did not stop the decrease of proteoglycan synthesis.

Ionic currents in cultured supraoptic neurons: actions of peptides and transmitters

The hypothalamo-neurohypophysial system has proved an excellent model for peptidergic neurons in the central nervous system. Electrophysiological studies using in vivo and in vitro preparations with extracellular and intracellular recording techniques have determined some of the intrinsic and extrinsic mechanisms that generate the striking firing patterns that the neurons exhibit. We have developed a dissociated cell preparation of these neurons and used patch clamp recording techniques to enable detailed studies of membrane properties underlying such activities. Cultured neonatal supraoptic neurons fired spontaneous action potentials which in some cells were distinctively patterned. Under voltage clamp, voltage-activated Na+, K+, and Ca2+ currents were recorded. K+ and Ca2+ currents were modulated by application of alpha-adrenergic agonists, and Ca2+ currents were also modulated by kappa-opioid agonists. The neurons were also sensitive to gamma-aminobutyric acid which acted directly on Cl- channels. Spontaneous, patterned activity, the presence of functional receptors for neurotransmitters and the ability to study the neurons under voltage clamp suggest that this is an excellent model system for studying these peptidergic neurons.

Location of angiotensin II binding sites on neuronal and glial cells of cultured mouse spinal cord: an autoradiographic study

Cultures of mouse spinal cord were used to visualize binding sites for [125I]angiotensin II (AII) by autoradiography. Visualization by light microscopy shows that neurones, but also glial cells possess angiotensin II binding sites which are located both on soma and processes. These findings open a new field of investigation for the understanding of the physiological significance of AII in the CNS.

Excitatory effect of noradrenaline on pacemaker cells in spinal cord primary cultures

Intracellular recordings were made from dissociated fetal mouse spinal cord neurons in primary culture. One particular type of neuron, with a large cell body (40-50 micron) and three to five thick neurites, exhibited rhythmic electrical activity of two different types, consisting of either spontaneous burst discharges or tonic action potential firing. Both types of activity appeared to be triggered by an endogenous membrane potential oscillation. Micropressure application of noradrenaline (10(-5) M in the delivery pipette) onto the surface of such cells evoked, in a dose-dependent manner, an increase in the input resistance with a depolarization of the membrane potential. The response to NA was potential-dependent. The maximum change in input resistance was observed at membrane potential values between -60 mV and -45 mV and the response was suppressed at membrane potentials lower than -80 mV. No modification of the response was observed in the presence of 50 mM of tetraethylammonium. The extrapolated reversal potential, close to -90 mV, was modified by increasing extracellular K+ concentration and unaltered by increasing the intracellular Cl- concentration. The decrease in K+ conductance induced by noradrenaline was Ca2+-dependent and reversibly suppressed by Ba2+ (6 mM) and Cd2+ (0.1 mM). This response to noradrenaline was suppressed in the presence of muscarine (10 microM) suggesting that noradrenaline decreases a K+ conductance related to M current. The noradrenaline evoked increase in input resistance was mediated by activation of an alpha 1 receptor site. Prazosin, an alpha 1 antagonist and phentolamine, an alpha 1 alpha 2 antagonist, reversibly suppressed the response in a competitive manner. Yohimbine, a competitive alpha 2 antagonist, also blocked the response, but in a noncompetitive manner. Clonidine, an alpha 2 agonist, isoprenaline, a beta agonist and L-alprenolol, a beta antagonist, had no effect.

Modeling of the evolution of bacterial densities in an eutrophic ecosystem (sewage lagoons)

The process of wastewater treatment was studied by modeling the relationships between physical, chemical, and biological (bacteria, phytoplankton, zooplankton) components of the sewage treatment lagoons of an urban wastewater center, based upon a two-year sampling program. The models of interactions between variables were tested by path analysis. The path coefficients were computed from the results of ridge regression, instead of linear multiple regression. The results show that fecal coliforms were effectively controlled by the environmental variables included in the model, which have a cyclic seasonal behavior. This control grew stronger with distance from the input (R (2)=0.71) to the output (R (2)=0.88) of the treatment plant, resulting in effective elimination of most enteric bacteria. Simultaneously, the ecosystem's community of aerobic heterotrophic bacteria became more independent from the model's predictive variables, with increased distance from the sewage input, thus demonstrating its maturation as an autonomous community in the lagoon ecosystem. Consequences of modeling are discussed, with respect to the understanding of biological wastewater treatment mechanisms and ecosystem dynamics and to plant management.

Chondromalacia of the fabella: a case report

A 46-year-old man suffered from chondromalacia of the fabella after minor trauma to the back of the knee. The condition was misdiagnosed initially as fasciitis, tendinitis, a Baker's cyst and a herniated lumbar intervertebral disc. Pathognomonic signs were pain behind the lateral femoral condyle on palpation and compression of the fabella and also on passive extension of the knee. Conservative management was unsuccessful. Excision of the fabella gave quick and lasting relief.

Evidence for bursting pacemaker neurones in cultured spinal cord cells

Intracellular recordings were made from dissociated mouse spinal cord cells in primary culture. One type of spinal cord neurone, with a large cell body (40-50 micron), 3-5 short neurites, and a mean resting potential of -65 mV, was found to fire rhythmic bursts of action potentials with a phase duration of approximately 1s when the membrane potential was depolarized to -55 mV. These bursts did not arise from spontaneous synaptic input, but appeared to result from endogenous ionic conductance properties of the membrane resembling those observed in molluscan bursting pacemaker neurones. Ionic conductances underlying this bursting activity were studied pharmacologically by local application of ionic conductance blockers. Pacemaker potentials depended on Na+ conductance, since tetrodotoxin and Na-free medium were the most potent agents for blocking spontaneous rhythmic activity. However, a Ca2+ conductance was involved in the depolarizing phase of membrane potential oscillations, since Ba2+ application increased oscillation amplitude. Action potentials observed during the bursts were Na+- and Ca2+-dependent. They did not differ significantly from those observed in other spinal cord neurones in culture. Application of tetraethylammonium, CoCl2, BaCl2 and 4-aminopyridine revealed at least three different potassium conductances which controlled this bursting pacemaker activity. A delayed potassium conductance controlled spike duration, a Ca-dependent potassium conductance controlled the duration of the burst and underlay the hyperpolarizing phase terminating the burst, and finally, a transient potassium conductance appeared to be involved in the control of phase duration. The demonstration that spinal cord neurones growing in monolayer culture display typical bursting pacemaker activity raises the possibility that bursting pacemaker neurones in the mammalian spinal cord may be involved in a phasic pattern generator that could control such activities as walking and the respiratory rhythm.

Characterization of two angiotensin II binding sites in cultured mouse spinal cord neurones

Characteristics of angiotensin II (AII) binding have been determined in cultured mouse spinal cord neurones using [125I]AII and [3H]AII. The Scatchard plot of equilibrium binding was curvilinear and could be described by postulating the existence of two different classes of independent binding sites (Kd1 = 0.43 nM, Bmax1 = 12.5 fmol/1.5 X 10(6) cells; Kd2 = 25.6 nM, Bmax2 = 220 fmol/1.5 X 10(6) cells). These values are in close agreement with the Kd values obtained from kinetic studies. The high affinity binding sites appeared to be similar to the single class of sites described in other studies. The relative inhibition potency of AII-related peptides was studied. Sar1,-Leu8-AII was the most potent in inhibiting specific AII binding. The characteristics of the two AII binding sites suggest that they correspond to two receptors as described in a previous electrophysiological approach using this model in our laboratory. Taken together, these data confirm that this model of neurones in primary culture is a unique and very attractive model of receptor studies. The classical criteria necessary for positive identification of a ligand-receptor have been satisfied: saturability, reversibility, specificity and most importantly correlation of the binding parameters and biological effects of AII.

Succession des communautés de gastéropodes dans deux milieux différant par leur degré d'eutrophisation

This paper compares the succession of gastropods in two environments that are adjacent in space but differ as to their eutrophic level. One is hypereutrophic (du Sud River), the other is mesotrophic (Richelieu River). Canonical correlation analysis brings out the main differences between these two stations, while principal component analysis is used to describe the succession of species within each community. These analyses indicate that the occurrence of gastropod species, as well as their development cycles, may be adapted to the particular synecological evolution of each environment. Thus, the species would not react directly to nutrient concentrations but indirectly, through the effects of these concentrations on oxygen content, plant cover, and predators. In these two environments, some benthic species seem to be good indicators of the eutrophic level of the ecosystem.

Dynamics of pollution-indicator and heterotrophic bacteria in sewage treatment lagoons

The spatio-temporal dynamics of pollution-indicator bacteria and aerobic heterotrophic bacteria were studied in the sewage treatment lagoons of an urban wastewater center after 26 months of biweekly sampling at eight stations in these lagoons. Robust statistical methods of time-series analysis were used to study successional steps (through chronological clustering) and rhythmic behavior through time (through contingency periodogram). The aerobic heterotrophic bacterial community showed two types of temporal evolution: in the first four stations, it seems mainly controlled by the nutrient support capacity of the sewage input, whereas in the remaining part of the lagoon, it seems likely that the pollution-indicator bacteria are gradually replaced by other bacterial types that are better adapted to this environment. On the other hand, the pollution-indicator bacteria showed an annual cycle which increased in amplitude at distances further from the wastewater source. The main events in this cycle were produced simultaneously at all stations, indicating control of these bacterial populations by climatic factors, which act through physical and chemical factors, and also through other biological components of this ecosystem (phytoplankton and zooplankton). Finally, we use results from this study to suggest a modified design for a future study program.

Electrophysiological effects of angiotensin II on cultured mouse spinal cord neurons

The effects of angiotensin II (AII) on the membrane properties of cultured spinal neurons were investigated using electrophysiological methods. In 26% of neurons tested AII induced changes in membrane potential and input resistance which varied according to the concentration of applied peptide. At low concentrations (10(-6) M), AII increased input resistance by an ionic mechanism which appears to involve a reduction in Cl- conductance. At higher concentration (10(-4) M), AII evoked depolarization associated with a decrease in input resistance. This response appears to depend on an increase in Na+ conductance. Our observations indicate that AII can have multiple effects on neuronal membrane properties dependent on the concentration of applied peptide.

Immunocytochemically identified vasopressin neurons in culture show slow, calcium-dependent electrical responses

From morphological characterization and intracellular recordings, monolayer cultures derived from fetal mouse hypothalami were found to include functionally differentiated peptide neurons, a number of which appear to contain vasopressin. These cells exhibited particular patterns of slow, calcium-dependent membrane depolarizations, resembling in their periodicity and duration the phasic activity of vasopressin neurons recorded extracellularly in vivo.

[Evolution of myocardial temperature following cardioplegia with and without complementary pericardial cooling. Experimental study]

Myocardial temperatures were measured after cardioplegia during cardiac surgery with and without pericardial cooling by a cold bath. Eight animals (50 kg pigs) were placed on cardiopulmonary bypass using a protocol reproducing clinical operating conditions as closely as possible: myocardial mass, median sternotomy, general hypothermia at 25 degrees. Two injections of cardioplegic solution were administered, one at aortic clamping and the other, 30 minutes later. Four animals (Group A) were used as reference. The four animals in Group B underwent pericardial irrigation with serum at 4 degrees C. Myocardial temperatures were measured at 9 anatomical sites every 10 minutes, (a total of 1008 measurements) and compared statistically. The results in the control group showed that myocardial warming after cardioplegia was intense and rapid at all sites. The sub-epi and sub-endocardial temperatures rose from 7 to 24 degrees in 30 minutes, and in the first 10 minutes, a rewarming of 8,5 degrees was observed. When pericardial cooling was used with cardioplegia, myocardial refrigeration was improved. The temperature remained below 15 degrees C (p less than 0,05 compared with Group A). Only a 3 degrees rise in temperature was observed at the 10th minute after cardioplegia (p less than 0,001). The rise temperature was of 2 degrees at the 20th minute, and 1 degree at the 30th minute. All temperatures remained below 15 degrees C (p less than 0,01). The authors emphasise the benefits of pericardial irrigation associated with cardioplegia for constant, durable and stable myocardial protection by cooling.

[Dibekacin in the treatment of septicemia]

During an open multicentric trial (17 centers), we have treated 62 septicemia by dibekacin, alone or associated with other antibacterial drugs. Taking into account the degree of severity of these patients, the results are considered satisfactory in 47 patients. 15 failures were noted (including 9 deaths). General and local tolerance were good, in spite of the duration of treatment.

[Treatment of urinary tract infections by dibekacin]

In this cooperative trial, 181 patients with various urinary tract infections were treated by dibekacin, a new hemi-synthetic aminoglycoside. Clinical and bacteriological results confirm the efficacy of dibekacin in this indication. Local and systemic tolerance, and thus renal and cochleo-vestibular, were very satisfactory.

A functional evenness index for microbial ecology

Microbial ecologists attempting to describe community structures through the use of synthetic parameters face enormous difficulties. These stem in part from the necessity of using standard taxonomic reference levels in a field where the species level is poorly defined. This paper presents an attempt to obviate this problem. A "functional evenness" index (E) is defined using information measures; it is based directly on the characteristics of the bacteria, as determined, for example, with the API 20B method. Comparisons of this index with classic structure indices, such as taxonomic evenness (Pielou) or systematic dominance (Hulburt), show that it behaves like an evenness index, while bypassing the taxonomic study required before computation of the classic indices. Its use is illustrated with samples of aerobic heterotrophic bacteria obtained from brackish lagoon sediments.

[Radionuclide inferior vena cavography and iliac venography (author's transl)]

Method of detection entirely harmless, the vena cava and iliac phlebography informs us about the degree and the lower level of a venous obstruction. This accuracy as to diagnosis is dependent on a dual imaging requiring the use of a gamma camera connected to a data processing system.

[Investigation of the thrombo-embolic disease by simultaneous lung scintigraphy and lower limb gamma-phlebography (author's transl)]

A venous thrombosis in the territory of the inferior vena cava and a possible embolus of the lung can be detected in one single examination by injecting 99 m Tc microagregates into a dorsal blood flow by this method, which associates radionuclide phlebography of the lower limbs and lung scanning, was carried out 140 times in 127 patients and resulted in the detection of 107 cases obliged us to investigate only one limb, gamma-phlebography appears to be a harmless procedure well suited to the study of the thrombo-embolic disease.

["Blue phlebitis" by thrombosis of the inferior vena cava on top of dysplastic stenosis]

A case of dysplastic stenosis of the infra-renal segment of inferior vena cava, with acute thrombosis and ischaemia of the left lower limb, is reported. Emergency thrombectomy, with pre- and post-surgery anticoagulant therapy, resulted in perfect recovery. As a comment on this case, various types of vena cava dysplasia, and possible causes of vena cava thrombosis, are briefly reviewed.

[Treatment of bacterial endocarditis with oral amoxicillin and intra-muscular gentamicin]

Fourteen patients suffering from bacterial endocarditis due to a streptococcus or staphylococcus were treated using a combination of amoxicillin per os in a dose of 1 gram every 2 or 3 hours and gentamicin in a dose of 60 mg intramuscularly every 6 or 8 hours. Two patients failed to tolerate amoxicillin, which had to be replaced by penicillin G. Two others, after a period of improvement, relapsed and were cured by the substitution of penicillin G given intravenously, in place of amoxicillin. The ten remaining patients were cured after a normal period of time had elapsed. Two of them were even treated at home. Bactericidal powers of serum obtained by the combination were satisfactory at between 1/16 to 1/4096 one hour after the administration of the antibiotics. This therapeutic protocol is thus effective, and has the advantage of improving the patient's comfort. It should nevertheless be reserved for use against sensitive organisms in patients without digestive problems, the bactericidal power of the serum being verified.

A field-trip microtechnique for studying fish leukocyte chromosomes

An ideal technique for field cytotaxonomy of fishes should be rapid, efficient, and time- and distance-independent. It should work on small as well as big specimens, and it should be amenable to air-drying. A technique meeting these requirements is as follows. A few drops of whole blood are collected from the specimens during field trips and kept in culture medium. In the laboratory, the medium is changed, Phytohemagglutinin is added, and the cells are cultivated at room temperature for about 3 days, after which air-drying fixation is performed. For very small specimens, the blood from several individuals may be pooled in one culture vessel.

[Familial amyloid neuropathy of Corino Andrade. Ultrastructural study of the peripheral nerve in 2 patients]

The authors describe two typical cases of Portuguese amyloid neuropathy in immigrants. One of the patients had been ill for only a short time while the other's condition had been developing over more than ten years. The first patient's neuropathy was characterized by a perforating ulcer of the foot and loss of sensation. The neurological disorder as well as the effect on general health were much more serious in the second patient. Neuro-muscular biopsy was carried out on each of these patients and revealed excessive endoneural amyloid and very severe lesions of nerve parenchyma mainly secondary to Wallerian degeneration. The results were compared with the few existing ultrastructural studies on the peripheral nerve in amyloid neuropathies.

The bearing of Phoxinus (Cyprinidae) hybridity on the classification of its North American species

Three populations of Phoxinus eos × P. neogaeus were found to form single Mendelian populations, by comparison with the parental species through a discriminant function. The hybrids of one of these populations were found to be fertile. A fourth hybrid collection, studied by three discriminant functions, was found to contain Semotilus margarita, P. eos × P. neogaeus, and hybrids of S. margarita with at least P. eos, but possibly P. eos × P. neogaeus. The presence of this hybrid, when related to the chromosome number of the species concerned, suggests the transfer of S. margarita to the genus Phoxinus.