Characterization of the in vivo cardiac electrophysiologic effects of high-dose cocaine in closed-chest, anesthetized dogs with normal hearts

OBJECTIVE: To characterize the cardiac electrophysiologic effects of cocaine. METHODS: In 8 dogs (9-13 kg), electrophysiologic parameters and programmed stimulation were undertaken using transvenous catheters at baseline, and after cocaine intravenous infusion (12 mg/kg bolus followed by 0.22 mg/kg/min for 25 minutes). RESULTS: Cocaine plasma levels (n=5) rose to 6.73± 0.56 mg/mL. Cocaine did not affect sinus cycle length and arterial pressure. Cocaine prolonged P wave duration (54±6 vs 73±4 ms, P<0.001), PR interval (115±17 vs 164±15 ms, P<0.001), QRS duration (62±10 vs 88±14 ms, P<0.001), and QTc interval (344±28 vs 403±62 ms, P=0.03) but not JT interval (193±35 vs 226±53 ms, NS). Cocaine prolonged PA (9±6 vs 23±8 ms, P<0.001), AH (73±16 vs 92±15 ms; P=0.03), and HV (35±5 vs 45±3ms; P<0.001) intervals and Wenckebach point (247±26 vs 280±28 ms, P=0.04). An increase occurred in atrial (138±8 vs 184± 20 ms; P<0.001) and ventricular (160±15 vs 187±25 ms; P=0.03) refractoriness at a cycle length of 300 ms. Atrial arrhythmias were not induced in any dog. Ventricular fibrillation (VF) was induced in 2/8 dogs at baseline and 4/8 dogs after cocaine. CONCLUSION: High doses of cocaine exert significant class I effects and seem to enhance inducibility of VF but not of atrial arrhythmias.

Study of some parameters affecting the in vitro cultivation of Plasmodium falciparum within saimiri sciureus red blood cells

The in vitro growth and multiplication of the erythrocytic stages of Plasmodium falciparum within Saimiri sciureus (squirrel monkey) red blood cells have been studied. Various parameters, such as the origin of the red blood cells and serum supplement, nature of the buffer, influence of the final pH of the medium, role of proteose peptone and glucose addition, were investigated. The selection of the best culture conditions led to the obtention of a reproducible in vitro growth of two parasite cycles in Saimiri erythrocytes, which is an useful achievement for in vitro studies. Our failure to establish a continuous culture line for longer than 19 days, could be explained by a dramatic increasing of osmotic fragility of the Saimiri red blood cells related to their small size.

Transport of methotrexate by the in vitro isolated rabbit proximal tubule.

The tubular transport of [3H]methotrexate was studied in isolated nonperfused and perfused superficial proximal tubular segments of rabbit kidneys. Reabsorption represented only 5% of perfused methotrexate, and appeared to be mostly of passive nature inasmuch as it was not modified by reducing the temperature or by ouabain. Cellular accumulation in nonperfused segments and secretion in perfused tubules were highest in the S2 segment and lower in the S3 and S1 segments. Secretion against a bath-to-lumen concentration gradient was observed only in S2 segments (with a maximum methotrexate secretory rate of 478 +/- 48 fmol/mm.min and an apparent Km of transport of 363 +/- 32 microM), and was inhibited by probenecid and folate. The low capacity for methotrexate secretion may be explained by a low capacity of transport across the basolateral membrane of the proximal cell as methotrexate was accumulated only to a low extent in nonperfused tubules (tissue water to medium concentration ratio of 8.2 +/- 1 in S2 segments). During secretion a small amount of methotrexate was metabolized; the nature of the metabolite(s) remains to be defined.

Cell mediated immunity in Chagas' disease: Trypanosoma cruzi antigens induce suppression of the in vitro proliferative response of mononuclear cells

The partial suppression of the cell-mediated immune response by Trypanosoma cruzi antigens in patients with Chagas' disease is demonstrated in a costimulation assay with T. cruzi antigens and Mycobacterium tuberculosis purified protein derivative (PPD) or Tetanus toxoid (TT). ononuclear cells from 13 patients with chagasic infection without evidence of heart disease, 10 patients with chagasic cardiomyopathy and 7 healthy blood donors were stimulated with antigen A (autoclaved epimastigotes), PPD, TT, PPD + A, PPD + TT and TT + A. The average percentage of suppression induced by costimulation of mononuclear cells with PPD and antigen A was 47.1% in patients with chagasic infection without heart disease (INF), 38.8% in patients with chagasic cardiomyopathy (CDM) and 23.3% in healthy controls. Similar values were observed when living trypomastigotes were used. A costimulatory study with PPD and TT, PPD and A and TT and A was carried out in 8 patients with chagasic infection, in order to evaluate the possibility that this difference could be due to a nonspecific inhibitory effect. The mean suppression induced by TT + PPD was -8.9, with TT + A was 52.7 and with PPD + A was 50.1. The data reported show that T. cruzi antigens induce a specific suppression of the proliferative responseof mononuclear cells, that might be relevant to the persistence of the parasite in the host.

The in vivo performance of magnetic particle-loaded injectable, in situ gelling, carriers for the delivery of local hyperthermia.

We investigated the use of in situ implant formation that incorporates superparamagnetic iron oxide nanoparticles (SPIONs) as a form of minimally invasive treatment of cancer lesions by magnetically induced local hyperthermia. We developed injectable formulations that form gels entrapping magnetic particles into a tumor. We used SPIONs embedded in silica microparticles to favor syringeability and incorporated the highest proportion possible to allow large heating capacities. Hydrogel, single-solvent organogel and cosolvent (low-toxicity hydrophilic solvent) organogel formulations were injected into human cancer tumors xenografted in mice. The thermoreversible hydrogels (poloxamer, chitosan), which accommodated 20% w/v of the magnetic microparticles, proved to be inadequate. Alginate hydrogels, however, incorporated 10% w/v of the magnetic microparticles, and the external gelation led to strong implants localizing to the tumor periphery, whereas internal gelation failed in situ. The organogel formulations, which consisted of precipitating polymers dissolved in single organic solvents, displayed various microstructures. A 8% poly(ethylene-vinyl alcohol) in DMSO containing 40% w/v of magnetic microparticles formed the most suitable implants in terms of tumor casting and heat delivery. Importantly, it is of great clinical interest to develop cosolvent formulations with up to 20% w/v of magnetic microparticles that show reduced toxicity and centered tumor implantation.

Assessing multiple sclerosis activity: is the in vitro production of tumor necrosis factor-alpha, interleukins 2, 6, 4, and 10, and immunoglobulin G of value?

Tumor necrosis factor (TNF) alpha, interleukins (IL) 2, 4, 6, and 10, and IgG oligoclonal bands (IgG OB) in vitro production was assessed, after whole-blood stimulation with lipopolysaccharide or concanavalin A, in 61 patients presenting with relapsing-remitting, relapsing-progressive, or chronic progressive multiple sclerosis. Multiple sclerosis patients were receiving no treatment or azathioprine (AZA), cyclosporin, cyclophosphamide, subcutaneous interferon (IFN) beta 1 a, or corticosteroids (CST). Statistical correlations significantly showed that: (a) AZA lowers TNF-alpha (P = 0.002) and increases IL-4 production (P = 0.0024), and IFN-beta 1 a increases TNF-alpha and decreases IL-4 levels; (b) CST has a negative effect on TNF-alpha, IL-6, and IL-4 synthesis; and (c) AZA, IFN-beta 1 a, and CST diminish IgG OB synthesis (P = 0.001). Although our study of the dynamics of TNF-alpha, IL-2, IL-4, IL-6, and IL-10 in vitro production generally found no statistically significant correlations (partly explained by the limited number of values in the various groups), IL-6 was shown to drop during the periods surrounding relapse (P = 0.05) in the absence of treatment, while TNF-alpha (P = 0.04) and IL-6 (P < 0.05) dropped before exacerbation in the presence of AZA. In vitro production of TNF-alpha was closely and positively correlated with that of IL-6, independently of clinical features. The enhanced production of IL-10 detected before or at relapse with AZA and IFN-beta 1 a (trends) may interfere with initiation of the immune reaction and with the development of new CNS lesions. Some discrepancies with previously published results stress the difficulties in studying the state of stimulation of different populations of leukocytes by using a variety of in vitro stimuli and in establishing a correlation between mRNA studies and the amount of final or active protein produced.

Influence of the in vivo deregulation of the expression of ntrk3 (trkc) on cortical development of a murine model of panic/anxiety disorder

Alteracions durant el desenvolupament cerebral produirien canvis en la connectivitat neuronal i la bioquímica cel•lular que podrien resultar en una disfunció cognitiva i/o emocional, desembocant a trastorns psiquiàtrics. Les neurotrofines intervenen en els processos del neurodesenvolupament i en la funcionalitat del cervell adult i, conseqüentment, serien bons candidats com a factors de predisposició en diverses malalties mentals. S’ha suggerit la implicació del receptor de la neurotrofina 3, TrkC, en el trastorn de pànic. Nosaltres proposem que la sobreexpressió del gen NTRK3 (TrkC) és un mediador comú dels desencadenants genètics i ambientals d’aquest trastorn. Concretament, la seva desregulació podria produir canvis estructurals i funcionals a l’escorça cerebral dels pacients pel seu paper durant l’establiment dels circuïts corticals i la neuroplasticitat a l’adult, probablement esdevenint elements de predisposició a patir atacs de pànic. Els objectius principals d’aquest treball han estat: 1/determinar la contribució específica del gen NTRK3 a les alteracions de l’escorça cerebral observades en pacients, utilitzant un model murí modificat genèticament (TgNTRK3), i 2/analitzar l’impacte específic de la sobreexpressió de NTRK3 sobre la corticogènesi durant estadis embrionaris o postnatals estudiant la neurogènesi i la neuritogènesi. Els resultats indiquen que la sobreexpressió de NTRK3 als ratolins produeix una reducció del gruix de l’escorça frontal, recapitulant la hipofrontalitat dels pacients, que comportaria una menor inhibició dels nuclis subcorticals del sistema límbic com l’amígdala, i alteracions citoarquitectòniques a l’escorça prefrontal medial que recolzen la hipòtesi del seu mal funcionament. Tanmateix, els ratolins TgNTRK3 presenten canvis estructurals a l’escorça somatosensorial, suggerint que el processament de la informació sensorial podria estar alterat, el que encara no s’ha explorat en pacients. La sobreexpressió de NTRK3 també afecta la neuritogènesi en cultius primaris corticals i modifica la resposta de les neurones a l’estimulació amb neurotrofines. Per tant, el fenotip cortical adult dels TgNTRK3 podria dependre d’alteracions durant la corticogènesi.

Ultrastructural study of the in vitro interaction between Biomphalaria glabrata hemocytes and Schistosoma mansoni miracidia

Biomphalaria glabrata and Schistosoma mansoni relationship was studied by light microscopy (LM) and freeze-fracture replica technique (FFR). We observed very thin cytoplasmic extensions of hemocytes in the LM, which then surround immobilize the miracidia. FFR images showed that the contact site between hemocytes cytoplasmic extensions and the external tegumentary coat involved only superficial layers of miracidia. Numerous vacuoles and filopodia were observed in the hemocyte cytoplasm, the latter binding with those from neighboring cells. In spite of the close interfilopodia contact, no cellular junctions were seen at these sites nor between filopodia-miracidia contact areas. The observed migration of hemocytes and their disposition in layers surrounding the miracidia in vitro correspond to previous studies.

The in vitro cytopathology of a porcine and the simian (SA-11) strains of rotavirus

Rotaviruses have been implicated as the major causal agents of acute diarrhoea in mammals and fowls. Experimental rotavirus infection have been associated to a series of sub-cellular pathologic alterations leading to cell lysis which may represent key functions in the pathogenesis of the diarrhoeic disease. The current work describes the cytopathic changes in cultured MA-104 cells infected by a simian (SA-11) and a porcine (1154) rotavirus strains. Trypan blue exclusion staining showed increased cell permeability after infection by both strains, as demonstrated by cell viability. This effect was confirmed by the leakage of infected cells evaluated by chromium release. Nuclear fragmentation was observed by acridine orange and Wright staining but specific DNA cleavage was not detected. Ultrastructural changes, such as chromatin condensation, cytoplasm vacuolisation, and loss of intercellular contact were shown in infected cells for both strains. In situ terminal deoxynucleotidyl transferase (Tunel) assay did not show positive result. In conclusion, we demonstrated that both strains of rotavirus induced necrosis as the major degenerative effect.

Fingermark detection based on the in situ growth of luminescent nanoparticles: towards a new generation of multimetal deposition

The in situ deposition of zinc oxide on gold nanoparticles in aqueous solution has been here successfully applied in the field of fingermark detection on various non-porous surfaces. In this article, we present the improvement of the multimetal deposition, an existing technique limited up to now to non-luminescent results, by obtaining luminescent fingermarks with very good contrast and details. This is seen as a major improvement in the field in terms of selectivity and sensitivity of detection, especially on black surfaces.

The in vitro leishmanicidal activity of hexadecylphosphocholine (miltefosine) against four medically relevant Leishmania species of Brazil

The in vitro leishmanicidal activity of miltefosine® (Zentaris GmbH) was assessed against four medically relevant Leishmania species of Brazil: Leishmania (Leishmania) amazonensis, Leishmania (Viannia) braziliensis, Leishmania (Viannia) guyanensis and Leishmania (Leishmania) chagasi. The activity of miltefosine against these New World species was compared to its activity against the Old World strain, Leishmania (Leishmania) donovani, which is known to be sensitive to the effects of miltefosine. The IC50 and IC90 results suggested the New World species harboured similar in vitro susceptibilities to miltefosine; however, miltefosine was approximately 20 times more active against the Old World L. (L.) donovani than against the New World L. (L.) chagasi species. The selectivity index varied from 17.2-28.9 for the New World Leishmania species and up to 420.0 for L. (L.) donovani. The differences in susceptibility to miltefosine suggest that future clinical trials with this drug should include a laboratory pre-evaluation and a dose-defining step.