Purified -SH-activated toxins (streptolysin O,alveolysin): New tools for determination of platelet enzyme activities

The purpose of this study was to examine the lytic effect on human platelet preparations (washed, gel-filtered and dextran-isolated) of two sulfhydryl-activated bacterial protein toxins, streptolysin 0 and and alveolysin, and to compare their efficacy with that of other disruptive procedures (freezing and thawing, ultrasonic, mechanical, or nystatin-toluene treatment) as a method for the determination of various platelet enzyme activities. The enzymes assayed were alkaline and acid phosphatases, monoamine oxidase, phenolsulfotransferase, N-acetyltransferase, hydroxyindole-0-methyltransferase, glutathione peroxidase and lactate dehydrogenase. In all cases, the lowest activities were found after freezing and thawing and/or ultrasonic disruption. The highest activities were always observed in the platelet lysates obtained after toxin, and in some instances after nystatin-toluene treatment. Intermediate values were obtained for mechanical disruption. The -SH-activated cytolysins thus appear to be appropriate and gentle tools for the assay of platelet enzymes when compared to the physical or chemical procedures generally employed.     

Pharmacokinetics of Propofol Administered by Target-controlled Infusion to Alcoholic Patients

Background: Chronic alcoholic patients are frequently presented for anesthesia and surgery. These patients require higher doses of propofol than control patients for induction of anesthesia, but whether this is because of changes in pharmacokinetics or pharmacodynamics is not known. This study was designed to investigate the influence of chronic ethanol intake on propofol pharmacokinetics.

Methods: Fifteen chronic alcoholic and 15 control patients, receiving propofol by target-controlled infusion for otolaryngologic surgery, were studied. Blood propofol concentrations were measured at regular intervals during and after the propofol infusion. Nonlinear mixed-effects population models (NONMEM) examining the influence of alcoholism were constructed. The influence of recovery on propofol pharmacokinetic parameters was also addressed.

Results: The total amount of propofol and the predicted and measured concentrations during all phases of anesthesia did not differ between the two groups. The fact that the measured concentrations at the time of opening eyes were similar further confirmed that the potency of propofol was not modified by the alcoholic status of the patients. Chronic alcoholism was associated with only mild changes in propofol pharmacokinetics (increase in rapid intercompartmental clearance and greater interindividual variability in the central volume of distribution). The rebound in concentration frequently observed during the recovery phase could be related to decreased propofol peripheral volumes of distribution despite an increase in elimination clearance.     

Quality of life in young urban children: does asthma make a difference?

The purpose of this study was to determine whether asthma status and severity have an impact on the quality of life of urban elementary school children. Participants were 1292 caregiver-child dyads from six schools serving low-income, ethnic minority, urban families; 53% of the children were female. Caregivers provided data on the children's asthma diagnosis and frequency in the last 12 months of asthma symptoms, use of medication for asthma, emergency room visits, and hospitalizations. Using the KINDL, a generic quality of life instrument, children reported on their health-related quality of life (HRQL). Results revealed a high prevalence of current asthma (18%). No differences were found in HRQL based on having current asthma or the severity of asthma as assessed by proxy measures of health care utilization and limited functioning. These findings are consistent with previous research indicating that HRQL is influenced by several factors other than asthma status and severity. The implications of these results for intervention are discussed.     

The electro-cochleogram

Summary Electro-physiological investigations of the peripheral auditory receptor in children and in some pathological cases are presented. After describing briefly the technical aspects of the method the Eectro-cochleogram, a few points are emphasized:The compromise between harmless procedure and precise recordings have led to choose to record from the bony promontory of the cochlea by means of a thin needle electrode introduced directly through the drum. This is done, in adults and in children over 8, under local contact anesthesia of the tympanic membrane, and in young children under light general anesthesia. The anesthetic drug used is administered by intramuscular injections and does not require intubation of the child.The main response that is looked for is the VIIIth nerve action potential evoked by clicks or tone pips. Owing to difficulties in determining where the microphonic potential that can be recorded is coming from, the cochlear microphonic is not taken into account and any signal which reverses when the phase of the stimulus is reversed is canceled out by adding, in the averaging computer, the responses to two series of identical stimuli but of opposite phases. This procedure does not modify the summating potential which then can be mixed with the action potential in the records.Owing to anatomical and electrical differences, the absolute value of the amplitude of the response is not as meaningful as its relative variations (amplitude and latency) with the intensity of the click.The results obtained in 29 children (1 month to 6 years old) are presented. The children all had either specific hearing impairement or more general disorders in which the hearing could be suspected. According to the different cases, thresholds have been found at every level from 0 to 90 dB (H. L.). No response could be observed, even to the click at 100 dB, in 9 children who all showed, with classical audiometry, absolute or near absolute deafness.However in 4 children, as well as in 3 adults and an older child, a particular abnormal pattern of the responses could be observed. All these cases presented complex neurological syndroms. These abnormal responses seem to reflect a cochlear disorder associated with a more general brain pathology.Finally physiological evidence for one type of recruitment is shown by the pattern of the input-output curves. Both the amplitude and latency curves show that the sensory and/or neural structures responsible for the low-intensity sensitivity are affected while the structures for high levels are normal.These few examples are presented in order to point out the possibilities of this method, which is definitely worthwhile in testing very young children and in difficult pathological cases.

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Zusammenfassung Die elektro-physiologische Untersuchung des peripheren Gehörempfangs bei Kindern und einigen pathologischen Fällen werden geschildert. Nach kurzer Beschreibung der technischen Aspekte der Methode — das Elektro-Cochleogramm — werden einige Punkte hervorgehoben:Der Kompromiß zwischen harmlosen Verfahren und präzisen Aufzeichen hat dazu geführt, die Ableitung von der Labyrinth-Kapsel mit einer dünnen Elektrodennadel zu wählen, welche direkt durch Trommelhöhle eingeführt wird. Dies wird bei Erwachsenen und Kindern über 8 Jahre bei lokaler Anaesthesie der Trommelfellmembrane durchgeführt und bei kleineren Kindern unter leichter Vollanaesthesie. Die angewandte Anaesthesiedroge wird i.m. eingespritzt und erfordert keine Intubation des Kindes.Als akustische Reizantwort auf Rechteckimpulse wird das Summenaktions-potential registriert. Die microphonies werden nicht berücksichtigt, sondern durch Registrierung in umgekehrter Phase bei Eingabe in einen Rechner aufgehoben. Damit kann das Summenaktionspotential klar erkannt werden. Eine Änderung des Summationspotentials erfolgt dadurch nicht.Auf Grund der anatomischen und elektrischen Unterschiede ist die absolute Größe der Amplitude der Reizantwort nicht so bedeutungsvoll wie ihre relative Variation (Schwingung und Latenz) je nach Intensität des Knackens.Anschließend werden die bei 29 Kindern (1 Monat bis 6 Jahre alt) erzielten Ergebnisse geschildert. All diese Fälle wiesen entweder spezifische Hörbehinderungen oder allgemeine Störungen auf, bei denen das Gehör betroffen sein konnte. Entsprechend den verschiedenen Fällen sind Schwellen bei jeder Stufe von 0 bis 90 dB (H. L.) festgestellt worden. Bei 9 dieser Kinder, welche alle bei der klassischen Audiometrie absolute oder nahezu absolute Taubheit aufwiesen, konnte keinerlei Reaktion, selbst bei 100 dB, beobachtet werden.Weiterhin konnte bei 4 Kindern sowie bei 3 Erwachsenen und bei einem älteren Kind ein besonderes, anormales Reaktionsmuster beobachtet werden. All diese Fälle wiesen komplexe, neurologische Syndrome auf. Diese anormalen Reaktionen schienen das Bild einer Cochleastörung in Verbindung mit einer mehr allgemeinen Gehirnstörung zu zeigen.Ein physiologischer Nachweis für einen Typ von Recruitment wird schließlich durch das Muster der Kennlinien erbracht. Beide, Amplituden- wie auch Latenzkurven, zeigen, daß die Receptoren und/oder Nervenstrukturen, welche für die Niedrig-Intensität-Empfindlichkeit verantwortlich sind, betroffen sind, wohingegen die Strukturen für die Hoch-Intensität-Empfindlichkeit normal sind.Diese wenigen Beispiele werden hervorgehoben, um auf die Möglichkeiten dieser Methode hinzuweisen, welche unbedingt Beachtung verdient bei Untersuchungen an kleinen Kindern und in schwierigen pathologischen Fällen.

     

A reinvestigation of the analgesic effects induced by stimulation of the periaqueductal gray matter in the rat. I. The production of behavioral side effects together with analgesia

It has been shown that stimulation-produced-analgesia (SPA) in the cat elicited from the periaqueductal gray matter (PAG) is obtained from sites located in the ventral part, particularly the dorsal raphé nucleus (DRN). These data contrast with the numerous studies performed in the rat in which efficient sites seem widely distributed throughout the PAG. These discrepancies led us to reinvestigate SPA from PAG and adjacent structures in the rat. Central stimulation was delivered through bipolar concentric electrodes (one for each animal). Analgesia was evaluated (before and during central stimulation) by measuring the modification in the vocalization threshold induced by electrical tail shocks or by considering the reaction of the animal to pinch. In contrast with the majority of previous studies, these experiments were performed on the totally freely-moving rat. The most striking result was that, in order to obtain analgesia from all regions of the PAG, it was necessary to apply intensities of central stimulation which also triggered other strong behavioral reactions. With intensities of PAG stimulation which did not induce such side effects, very few effective analgesic sites were found (21/129 sites of which 14/83 were strictly located in the PAG). However, it was possible to define two 'pure analgesic regions', both located in the ventral PAG: one centered on the dorsomedial part of the DRN and the other one situated in the ventrolateral PAG. No modification of nociceptive thresholds was observed when stimulating the dorsal and dorsolateral parts of the PAG as well as structures adjacent to these regions; in some rats, an increase in pain reactivity was even noted. When the intensity of central stimulation (applied to the various parts of the PAG) was increased, some stereotyped 'behavioral responses' occurred depending on the location of the stimulation site: motor effects (gnawing, rotation or tremor) in the ventral PAG and aversive effects (flight, jumping and on occasions, distress vocalizations) in the dorsal, dorsolateral PAG and in the ventral region just surrounding the cerebral aqueduct. Under these conditions, analgesia was obtained from practically the entire PAG, the vocalization threshold being increased dramatically on occasions. It must be emphasized that antinociceptive effects associated with other obvious behavioral manifestations (aversive ones) were also obtained from sites located outside the PAG (colliculi and tectum adjacent to the dorsal and dorsolateral PAG).(ABSTRACT TRUNCATED AT 400 WORDS)     

Innovations in classical hormonal targets for endometriosis

Endometriosis is a chronic disease of unknown etiology that affects approximately 10% of women in reproductive age. Several evidences show that endometriosis lesions are associated to hormonal imbalance, including estrogen synthesis, metabolism and responsiveness and progesterone resistance. These hormonal alterations influence the ability of endometrial cells to proliferate, migrate and to infiltrate the mesothelium, causing inflammation, pain and infertility. Hormonal imbalance in endometriosis represents also a target for treatment. We provide an overview on therapeutic strategies based on innovations of classical hormonal mechanisms involved in the development of endometriosis lesions. The development phase of new molecules targeting these pathways is also discussed.

Endometriosis is a chronic disease involving young women and additional biological targets of estrogen and progesterone pharmacological manipulation (brain, bone and cardiovascular tissue) need to be carefully considered in order to improve and overcome current limits of long-term medical management of endometriosis.     

Treatment of health-care-associated infections caused by Gram-negative bacteria: a consensus statement

This consensus statement presents the conclusions of a group of academic and industrial experts who met in London in September, 2006, to consider the issues associated with the treatment of hospital infections caused by Gram-negative bacteria. The group discussed the severe clinical problems arising from the emergence of antibiotic resistance in these bacteria and the lack of new antibacterial agents to challenge the threat. The discovery of new drugs active against hospital-acquired Gram-negative bacteria is essential to prevent a future medical and social catastrophe. An important strategy to promote drug discovery will be the development of focused cooperations between academic institutions and small pharmaceutical companies.     

Potential therapeutic interest of adenosine A2A receptors in psychiatric disorders

The interest on targeting adenosine A(2A) receptors in the realm of psychiatric diseases first arose based on their tight physical and functional interaction with dopamine D(2) receptors. However, the role of central A(2A) receptors is now viewed as much broader than just controlling D(2) receptor function. Thus, there is currently a major interest in the ability of A(2A) receptors to control synaptic plasticity at glutamatergic synapses. This is due to a combined ability of A(2A) receptors to facilitate the release of glutamate and the activation of NMDA receptors. Therefore, A(2A) receptors are now conceived as a normalizing device promoting adequate adaptive responses in neuronal circuits, a role similar to that fulfilled, in essence, by dopamine. This makes A(2A) receptors particularly attractive targets to manage psychiatric disorders since adenosine may act as go-between glutamate and dopamine, two of the key players in mood processing. Furthermore, A(2A) receptors also control glia function and brain metabolic adaptation, two other emerging mechanisms to understand abnormal processing of mood, and A(2A) receptors are important players in controlling the demise of neurodegeneration, considered an amplificatory loop in psychiatric disorders. Current data only provide an indirect confirmation of this putative role of A(2A) receptors, based on the effects of caffeine (an antagonist of both A(1) and A(2A) receptors) in psychiatric disorders. However, the introduction of A(2A) receptors antagonists in clinics as anti-parkinsonian agents is hoped to bolster our knowledge on the role of A(2A) receptors in mood disorders in the near future.     

In vitro push-out strength of seven luting agents to dentin

PURPOSE: New luting agents, described as resin-modified glass-ionomer cements and compomers, have been developed during the last decade to improve the retention of cemented restorations. The aims of this study were to (1) compare the push-out strength of these new luting materials against both conventional cements and bonding luting agents, and (2) evaluate the influence of dentin surface treatment on both glass-ionomer cement and 4-META adhesive resin push-out strength. MATERIALS AND METHODS: Conical standardized cavities were drilled in the center of coronal dentin disks. Ninety sandblasted Ni-Cr inlays, divided into nine batches, were luted into the cavities according to the surface treatment and the nature of the following luting agents: zinc phosphate cement, zinc polycarboxylate cement, type 1 glass-ionomer +/- polyacrylic acid, resin-modified glass-ionomer, polyacid-modified composite resin, filled bis-GMA phosphate ester resin, and 4-META adhesive resin +/- application of activated monomer. Each specimen was placed in a holding device, and a steel rod was used to apply a force on the inlay until rupture occurred. The push-out strength was calculated, and the failure mode was controlled. RESULTS: There were significant differences between some of the groups. The highest push-out strength was achieved by the 4-META adhesive resin after application of activated monomer. The lowest value was attained with zinc phosphate and polycarboxylate cements. CONCLUSION: Both resin-modified glass-ionomer and polyacid-modified composite resin luting materials exhibited a push-out strength similar to resin-based materials. Specific dentin surface treatments significantly enhanced the push-out strengths of glass-ionomer cement and 4-META adhesive resin.     

The human spleen is a major reservoir for long-lived vaccinia virus-specific memory B cells

The fact that you can vaccinate a child at 5 years of age and find lymphoid B cells and antibodies specific for this vaccination 70 years later remains an immunologic enigma. It has never been determined how these long-lived memory B cells are maintained and whether they are protected by storage in a special niche. We report that, whereas blood and spleen compartments present similar frequencies of IgG⁺ cells, antismallpox memory B cells are specifically enriched in the spleen where they account for 0.24% of all IgG⁺ cells (ie, 10-20 million cells) more than 30 years after vaccination. They represent, in contrast, only 0.07% of circulating IgG⁺ B cells in blood (ie, 50-100 000 cells). An analysis of patients either splenectomized or rituximab-treated confirmed that the spleen is a major reservoir for long-lived memory B cells. No significant correlation was observed between the abundance of these cells in blood and serum titers of antivaccinia virus antibodies in this study, including in the contrasted cases of B cell– depleting treatments. Altogether, these data provide evidence that in humans, the two arms of B-cell memory—long-lived memory B cells and plasma cells—have specific anatomic distributions—spleen and bone marrow—and homeostatic regulation.