Comparative experimental study of myocardial protection with crystalloid solutions for heart transplantation / Estudo comparativo experimental da proteção miocárdica com soluções cristalóides para transplante cardíaco

BACKGROUND: There is a growing need to improve myocardial protection, which will lead to better performance of cardiac operations and reduce morbidity and mortality. Therefore, the objective of this study was to compare the efficacy of myocardial protection solution using both intracellular and extracellular crystalloid type regarding the performance of the electrical conduction system, left ventricular contractility and edema, after being subjected to ischemic arrest and reperfusion. METHODS: Hearts isolated from male Wistar (n=32) rats were prepared using Langendorff method and randomly divided equally into four groups according the cardioprotective solutions used Krebs-Henseleit-Buffer (KHB), Bretschneider-HTK (HTK), St. Thomas-1 (STH-1) and Celsior (CEL). After stabilization with KHB at 37ºC, baseline values (control) were collected for heart rate (HR), left ventricle systolic pressure (LVSP), maximum first derivate of rise left ventricular pressure (+dP/dt), maximum first derivate of fall left ventricular pressure (-dP/dt) and coronary flow (CF). The hearts were then perfused at 10ºC for 5 min and kept for 2 h in static ischemia at 20ºC in each cardioprotective solution. Data evaluation was done using analysis of variance in completely randomized One-Way ANOVA and Tukey's test for multiple comparisons. The level of statistical significance chosen was P<0.05. RESULTS: HR was restored with all the solutions used. The evaluation of left ventricular contractility (LVSP, +dP/ dt and -dP/dt) showed that treatment with CEL solution was better compared to other solutions. When analyzing the CF, the HTK solution showed better protection against edema. CONCLUSION: Despite the cardioprotective crystalloid solutions studied are not fully able to suppress the deleterious effects of ischemia and reperfusion in the rat heart, the CEL solution had significantly higher results followed by HTK>KHB>STH-1.

INTRODUÇÃO: Existe crescente necessidade de aprimorar a proteção miocárdica, para melhor desempenho das operações cardíacas e diminuição da morbimortalidade. Portanto, o objetivo deste estudo foi comparar a eficácia da proteção miocárdica usando tanto solução cristaloide tipo intracelular como extracelular quanto ao desempenho do sistema de condução elétrica, contratilidade do ventrículo esquerdo e edema, após parada isquêmica e posterior reperfusão. MÉTODOS: Corações isolados de ratos Wistar foram montados em Langendorff e aleatoriamente divididos em quatro grupos. de acordo com as soluções cardioprotetoras utilizadas Krebs-Henseleit-Buffer (KHB), Bretschneider-HTK (HTK), St. Thomas-1(STH-1) e Celsior (CEL). Após a estabilização com KHB a 37ºC, valores basais (controle) foram coletados para frequência cardíaca (FC), pressão sistólica do ventrículo esquerdo (PSVE), derivada máxima de aumento da pressão ventricular esquerda (+dP/dt), derivada máxima de queda da pressão ventricular esquerda (-dP/dt) e fluxo coronariano (FCo). Os corações foram então perfundidos a 10ºC por 5 min e mantidos por 2 h em isquemia estática a 20ºC em cada solução cardioprotetora. Avaliação dos dados foi por análise de variância inteiramente casualizados em One-Way ANOVA e teste de Tukey para comparações múltiplas. O nível de significância estatística escolhido foi P<0,05. RESULTADOS: Houve recuperação da FC com todas as soluções utilizadas. A avaliação da contratilidade ventricular esquerda (PSVE, +dP/dt e -dP/dt) demonstrou que o tratamento com a solução CEL foi melhor em comparação às outras soluções. Ao analisar o CF, a solução HTK indicou melhor proteção contra edema. CONCLUSÃO: Apesar das soluções cristaloides cardioprotetoras estudadas não serem capazes de suprimir os efeitos deletérios da isquemia e reperfusão no coração de ratos, a solução CEL apresentou resultado superior seguido por HTK>KHB>STH-1.

tlpA gene expression is required for arginine and bicarbonate chemotaxis in Helicobacter pylori

About half of the human population is infected with Helicobacter pylori, a bacterium causing gastritis, peptic ulcer and progression to gastric cancer. Chemotaxis and flagellar motility are required for colonization and persistence of H. pylori in the gastric mucus layer. It is not completely clear which chemical gradients are used by H. pylori to maintain its position. TlpA, a chemotaxis receptor for arginine/ bicarbonate, has been identified. This study aimed to find out whether tlpA gene expression is required for the chemotactic response to arginine/bicarbonate. Wild-type motile H. pylori ATCC 700392 and H. pylori ATCC 43504, a strain having an interrupted tlpA gene, were used. Also, a tlpA-knockout mutant of H. pylori 700392 (H. pylori 700-tlpA::cat) was produced by homologous recombination. Expression of tlpA was assessed by a Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay. Chemotaxis was measured as a Relative Chemotaxis Response (RCR) by a modified capillary assay. H. pylori 700392 presented chemotaxis to arginine and sodium bicarbonate. H. pylori 700-tlpA::cat showed neither tlpA gene expression nor chemotaxis towards arginine and bicarbonate. Besides confirming that TlpA is a chemotactic receptor for arginine/bicarbonate in H. pylori, this study showed that tlpA gene expression is required for arginine/bicarbonate chemotaxis.

Effect of bicarbonate on fluoride reactivity with enamel / Efeito do bicarbonato na reatividade do fluoreto com esmalte

Purpose: Bicarbonate (HCO-3) is an alkaline and buffering substance found in dentifrices, which could improve the anti-caries effect of fluoride (F). However, HCO-3 could reduce the formation of calcium fluoride-like (CaF2), the most important product of F reactivity with enamel, whose formation is higher in low pH. The aim of this in vitro study was to evaluate if HCO-3 interferes with the reactivity of F with human enamel. Methods: Five dentifrice formulations were evaluated: placebo of F and HCO-3 (pH 7.0); HCO-3 (pH 9.0); F (pH 7.0); F (pH 9.0) and F+HCO-3 (pH 9.0). F dentifrices contained NaF and all dentifrices were silica-based. The concentrations of total F (TF), CaF2 and firmly bound F (FA, fluorapatite-like) formed in enamel after 1-min reaction with dentifrice slurries (1:3) were determined. Results: The formation of TF, CaF2 and FA was reduced in 22.1 %, 47.9 % and 4.8 %, respectively, by the presence of HCO-3 in the dentifrice formulation. Conclusion: This in vitro data suggest that addition of HCO-3 to a dentifrice may interfere with the reactivity of F with enamel, reducing mainly the concentration of CaF2 formed.

Objetivo: O bicarbonato (HCO-3 ) é uma substância alcalina e tamponante encontrada em dentifrícios, que poderia melhorar o efeito anticárie do fluoreto (F). No entanto, HCO-3 poderia reduzir a formação de fluoreto de cálcio (CaF2), o mais importante produto da reatividade do F com esmalte, cuja formação é maior em baixo pH. O objetivo deste estudo foi avaliar in vitro se o HCO-3 interfere na reatividade do F com o esmalte humano. Metodologia: Cinco formulações de dentifrícios foram avaliadas: placebo de F e HCO-3(pH 7,0); HCO-3 (pH 9,0); F (pH 7,0); F (pH 9,0) e F+HCO-3 (pH 9,0). Os dentifrícios fluoretados continham NaF e todos continham sílica como abrasivo. As concentrações de F total (FT), CaF2 e F firmemente ligado (FA, tipo flúorapatita) formadas no esmalte após 1 minuto de reação com as suspensões dos dentifrícios (1:3) foram determinadas. Resultados: A formação de FT, CaF2 e FA foram reduzidas em 22,1 %; 47,9 % e 4,8 %, respectivamente, pela presença de HCO-3 na formulação do dentifrício. Conclusão: Os resultados in vitro sugerem que a adição de HCO-3 a um dentifrício pode interferir com a reatividade do F com o esmalte, principalmente reduzindo a concentração de CaF2 formado no esmalte.

Trimetazidina como aditivo em solução cardioplégica sem pré-tratamento não traz proteção adicional ao miocárdio isquêmico: estudo em modelo suíno de coração isolado / Trimetazidine as cardioplegia addictive without pre-treatment does not improve myocardial protection: study in a swine working heart model

OBJETIVO: Verificar, em modelo experimental de coração isolado de suínos, se a associação da trimetazidina à solução cardioplégica promove melhora no desempenho do coração. MÉTODOS: O modelo experimental utilizou suínos Large-White, com coração isolado perfundido por suporte de outro animal em modo de execução de trabalho ("working heart state"). Foram divididos em três grupos (n = 6), submetidos a isquemia regional seguida de isquemia global, que recebiam um dos três tratamentos: solução St Thomas (ST), solução St Thomas acrescida de trimetazidina (TMZ) e grupo controle (Co). Durante período de reperfusão, aos 30, 60 e 90 minutos, foram medidos parâmetros hemodinâmicos de contratilidade e metabólicos, obtendo-se assim a elastância máxima (Emáx), o índice de trabalho sistólico pré-recrutável (PRSW), "dureza" do ventrículo (EDPRV), fluxo coronariano, consumo de oxigênio e dosagens de lactato e glicose. Os resultados foram analisados estatisticamente. RESULTADOS: Em relação aos parâmetros hemodinâmicos de contratilidade, não houve diferença estatística significante entre os três grupos. Houve produção crescente de lactato nos três grupos de forma uniforme quanto maior o tempo de reperfusão. O fluxo coronariano, o consumo de oxigênio e o consumo de glicose tiveram grande variação entre os diferentes tempos medidos, mas sem diferença entre os três tratamentos. O peso final do ventrículo esquerdo foi significativamente menor no grupo trimetazidina (TMZ) do que nos demais. CONCLUSÃO: A administração da trimetazidina associada como adjuvante à solução cardioplégica, sem pré-tratamento, não demonstrou benefício hemodinâmico ou metabólico em modelo experimental "working heart" de coração isolado em porcos.

OBJECTIVE: The aim of this study is to verify in an isolated working heart swine model if the acute administration of trimetazidine to cardioplegia, without pre=treatment improves heart performance. METHODS: Eighteen pairs of swines were used in this working heart model, divided into three groups (n = 6) that underwent regional and global ischemia. Each group was selected to a different treatment: St Thomas cardioplegia (ST), St Thomas enriched with trimetazidine (TMZ) and control group (Co). Data was collected during reperfusion period at 30, 60 and 90 minutes. Hemodinamic parameters such as elastance contractility index (Emax), preload recruitable stroke work relationship (PRSW) and heart "stiffness" (EDPVR) were measured. Other data included coronary flow, lactate, oxygen and glucose consumption. Results were statistically analyzed. RESULTS: All contractility data were not significantly different among three groups. Lactate became constantly higher according to time uniformly in all three groups. Coronary flow, glucose consumption and oxygen consumption presented large variations during time periods but according to treatments showed no statistical differences in all three groups. Left ventricle final weight was significantly lower in trimetazidine group compared to both other groups. CONCLUSION: Administration of trimetazidine enhanced cardioplegia, without pre-treatment, showed no hemodinamic or metabolic improvement in swine isolated working heart model.

Limited proteolysis by trypsin influences activity of maize phosphoenolpyruvate carboxylase.

Maize phosphoenolpyruvate carboxylase (PEPC) was rapidly and completely inactivated by very low concentrations of trypsin at 37 degrees C. PEP+Mg2+ and several other effectors of PEP carboxylase offered substantial protection against trypsin inactivation. Inactivation resulted from a fairly specific cleavage of 20 kDa peptide from the enzyme subunit. Limited proteolysis under catalytic condition (in presence of PEP, Mg2+ and HCO3) although yielded a truncated subunit of 90 kDa, did not affect the catalytic function appreciably but desensitized the enzyme to the effectors like glucose-6-phosphate glycine and malate. However, under non-catalytic condition, only malate sensitivity was appreciably affected. Significant protection of the enzyme activity against trypsin during catalytic phase could be either due to a conformational change induced on substrate binding. Several lines of evidence indicate that the inactivation caused by a cleavage at a highly conserved C-terminal end of the subunit.

Intestinal transport of water, sodium & glucose from an electrolyte solution with & without bicarbonate.

In this study we have evaluated the role of bicarbonate on water and sodium transport in normal and secreting ilea of rabbits as controversy exists regarding the inclusion of bicarbonate in oral rehydration solution (ORS). In anaesthetized rabbits 10 cm closed ileal loops were constructed and filled with 5 ml of an electrolyte solution with and without bicarbonate, which contained polyethylene glycol (PEG; mol wt 4,000) as a non-absorbable marker. The fluid was withdrawn after an hour and analyzed for PEG, sodium and glucose. Similar studies were carried out in loops one hour after exposure to 1 microgram/ml of purified cholera toxin. Body temperature was maintained at 37 degrees C during the experiment by using a lamp. The mean +/- SE of water and sodium absorption, with bicarbonate versus without bicarbonate, was -1.4 +/- 0.1 vs -1.1 +/- 0.3 ml/h/10 cm, and -340.8 +/- 23.0 vs -308.4 +/- 35.6 mM/h/10 cm, respectively from secreting rabbit ilea. A similar effect was observed in normal ilea. It is concluded that bicarbonate containing electrolyte solution has no additional promoting effect on water and sodium absorption in normal or secreting ilea of rabbits.

Effect of HCO3 and pH on ion transport in the posterior intestine of the freshwater-adapted teleost Anguilla anguilla

The intestinal mucosa may be exposed to acidic or alcaline solutions due to liberation of digestive secretions. In several situations blood pH may also change. Consequently, the effects of HCO-3, CO2, and pH variation of medium on the ion transport acrross the posterior intestine of the eel (Anguilla anguilla) adapted to freshwater were studied in terms of fractional values of short-circuit current (SCC), transepithelial potential difference (TPD) and conductance (G). Immature eels weighing 100-200 g were used. The control physiological solution contained: 118.5 mM NaCl, 25.0 mM NaHCO3, 3.0 mM CaCl2.2H2O, 4.7 mM KCl, 1.0 mM MgCl2.6H2O, 5.0 mMD-glucose, 10.0 mM D-mannitol, pH 7.80, and was gassed with 98 percent O2-2 percent CO2. Control values(N = 21) were: SCC = 51.90 + or - 51.90 + or - 2.8 µA.cm-2, TPD = 2.33 + or - 0.1 mV, G = 22.43 + or - 0.6 mS.cm-2. At constant pH, the reduction of HCO-3 concentration to 50 percent and 10 percent did not alter the values of SCC and TPD, but G increased with HCO-3 reduction to 10 percent. In the absence of HCO-3, SCC, TPD and G (slightly) decreased, but 1.5 mM HCO-3 still maintained the ion transport within control values, at constant pH. Comparing PH values from 6.65 to 8.61, higher values of SCC and TPD were observed at PH 7.45, but were little affected below and above this pH. There was a significant correlation between pH and SCC and TPD values; from the regression equations (1) SCC was zero at pHs below 6.62 and above 8.78 and (2) TPD was zero below 6.50 and above 8.71

Efecto de la alcalinización y el calentamiento de las soluciones anestésicas sobre el periodo de latencia en el bloqueo de plexo axilar vía axilar / Effects of anesthetic Warming and alcalinization upon the latency period in axilary blockade through axilary approach

Se estudiaron tres grupos de 10 pacientes cada uno, de ambos sexos, edad promedio de 34.8 ñ 8.8 años, peso promedio de 68.8 ñ 2.3 zkg. talla promedio de 156 ñ cm. y estados físicos 1 y 2, programados para cirugía electiva ortopédica o reconstructiva del miembro toráxico. A todos ellos se les administró lidocaína al 2 por ciento con epinefrina para bloqueo de plexo braquial vía axilar a dosis de 7 mg/kg. al grupo I sin modificaciones , al grupo II se adicionó bicarbonato de sodio y al grupo III se aumentó la temperatura a 37ºC, para reducir el tiempo de latencia. El tiempo promedio de latencia observado para el grupo I fue de 15.2 ñ 7.3 minutos y para el grupo II fue de 9.1 ñ 1.9 minutos, existiendo diferencias significativas estadísticamente p<0.01. El tiempo promedio de latencia para el grupo III fue de 2.4 ñ 1.3 minutos y en comparación con los dos grupos previos se aprecia una diferencia significativa estadísticamente (P<0.005). En suma, tanto la alcalinización como el calentamiento de las soluciones anestésicas con eficaces para disminuir el tiempo de la latencia

Carotid body chemoreception: the importance of CO2-HCO3- and carbonic anhydrase. (review)

The current hypotheses of carotid body (CB) chemoreception regard the glomus cells as the initial site of stimulus transduction. The consensus is that the transduction of chemical stimulus is coupled with the release of transmitter(s) from the glomus cells, which in turn generates action potentials in the afferent nerve terminals. Carbonic anhydrase (CA) is present in the glomus cells of the CB. Inhibition of CA activity in the CB in situ reduces the carotid chemosensory responses to CO2 and to O2, suggesting a common mechanism of chemosensing for both stimuli. However, CA inhibitors also block the red blood cell enzyme. Thus, the CO2 hydration reaction does not come to completion within the transit time of the blood from the lung to the CB. A steady-state reaction is not reached until later and so the PCO2 and pH levels in arterial blood samples are not the same as those sensed by the CB. Experiments in vitro using cat CB perfused and superfused with cell-free solutions, which had been pre-equilibrated with respiratory gases, strongly support the proposition that the CA activity in CB cells is essential for the speed and amplitude of the initial response to CO2 and for its subsequent adaptation. The immediate response to hypoxia also is delayed, but the late steady-state was less dependent on CA activity. In the nominal absence of CO2-HCO3- from the perfusate, hypoxic chemoreception persisted and its magnitude is not affected by CA inhibition, except for a delay which may be due to the initial alkaline pH of the glomus cells. Recent experiments performed in isolated glomus cells and in the whole CB show that hypoxia does not modify significantly the intracellular pH. By its simple catalytic function, CA can speed up the approach of the CO2 hydration reaction to equilibrium. However, CA may also contribute in the steady-state to the regulation of pHi by providing a continuous supply of H+ and HCO3-. Furthermore, CA performs a facilitatory role in the physiological chemosensory responses to CO2 and O2 in the presence of extracellular CO2-HCO3-. This role is likely to be related to the ion exchanger function and then to pHi regulation in the chemoreceptor cells

Evidence in support of a chemiosmotic mechanism for stimulated prolactin release

Para comprobar la participación de un mecanismo quimiosmótico en la exocitosis de prolactina (PRL) se utilizaron células anterohipofisarias dispersas provenientes de ratas hembra. Luego de un cultivo primario éstas se incubaron en medios que contenían iones de bicarbonato o isetionato, probenecid y carboinlcianuro p-trifluorometoxi-fenilhidrazona (CCTP). Células incubadas sin estos aditivos o estimuladas con dibutiriladenosina 3:5 monofosfato cíclico se utilizaron como controles. Además se preparó una suspensión de gránulos secretorios aislados para estudiar el efecto de elevadas presiones osmóticas. La inhibición del transporte aniómico con probenecid siempre redujo significativamente la liberación de PRL; con el bicarbonato, en cambio, se obtuvo el efecto opuesto. El ionóforo de protones CCTP solamente inhibió la secreción estimulada de PRL y la substitución del cloro por el isetionato no produjo efectos significativos. Finalmente se pudo observar que elevadas presiones osmóticas suprimían la lisis de los gránulos prolactínicos cuando el medio de incubación contenía bicarbonato. Los resultados indicam que un mecanismo quimiosmótico, dependiente de protones e iones bicarbonato, , interviene en la liberación estimulada de PRL y que un mecanismo diferente, independiente de protones, devería considerarse para la secreción basal de PRL

Rol de proton H+ y del bicarbonato en la citoproteccion gastrica adaptativa / Role of the H+ proton and bicarbonate in the adaptative gastric cytoprotection

En ratas Wistar se estudió el mecanismo no conocido de la citoprotección gástrica adaptativa, inducida por etanol al 20% y posterior injuria con etanol al 70%. El pretratamiento con Indometacina o Cl2 Hg no impidió la citoprotección gástrica adaptiva, indicando que en su mecanismo no participan ni las PGs endógenas, ni el mucus gástrico, respectivamente. En cambio, el pretratamiento con Ranitidina bloqueó y aun agravó las lesiones gástricas inducidas por el etanol -etanol; por el contrario, dicho fenómeno anterior fue revertido por el etanol al 20% acidificado. Se concluyó que la retrodifusión de H+ y el bicarbonato juegan roles importantes en el mecanismo de la citoprotección gástrica adaptativa

Efeito da infusäo de soluçäo de bicarbonato de sódio sobre o equilíbrio ácido-base materno-fetal durante o trabalho de parto / Effect of the infusion of sodium bicarbonate over the acid-base equilibrium maternal and fetal, during the parturition

Foram estudados os efeitos da infusäo endovenosa de bicarbonato de sódio na mäe e feto, na dose de 1mEq/Kg de peso, em um grupo de 30 parturientes atendidas no Hospital das Clínicas da Faculdade de Medicina de Ribeiräo Preto, USP. As parturientes foram divididas em três grupos; em dois deles, os fetos foram considerados normais e, no terceiro, em sofrimento

Efecto del bicabornato de sodio en el aislamiento primario de Neisseria gonorrhoeae / Effect of sodium bicarbonate on primary isolation of Neisseria gonorrhoeae

Se estudia el efecto del bicarbonato de sodio añadido directamente al medio de crecimiento, para el aislamiento primario de Neisseria gonorrhoeae. Se investigaron 105 muestras de exudados uretales de varones con uretritis, que acudieron al laboratorio de microbiología del hospital provincial "Saturnino Lora", y se procedió a inocular las mismas en agar chocolate, base GG; en placas de Petri y el mismo medio, pero con NaHCO3 en concentraciones de 0,036 y 0,072 molar, utilizando frascos de 120 ml con tapas de rosca. La placas se incubaron en atmósfera de CO2 (método de la vela) y los fracos en atmósfera normal; ambos a 35-C durante 24 y 48 horas. No hubo diferencia entre los resultados obtenidos mediante los dos métodos, lo que afirma la utilidad del bicarbonato de sodio para el fin propuesto. Se establecen conclusiones y se formulan recomendaciones. El trabajo se ilustra con cuadros

Modificaciones del estado ácido-base del líquido cefalorraquídeo por efecto de la administración de alcalinizantes (bicarbonato de sodio y THAM) / Changes of the acid-base equilibrium of the cerebrospinal fluid by effect of administration of alkaline agents (sodium bicarbonate and THAM)

Cuando se infunde bicarbonato de sodio intravenoso el propósito de corregir la acidosis metabólica se obtienen resultados opuestos en el líquido cefalorraquídeo. La caída del pH en el líquido y, por lo tanto, en el sistema nervioso central, puede ocasionar empeoramiento en el estado de conciencia, modificación de la ventilación y modificación de la perfusión cerebral. Por el contrario, la infusión de THAM - Tris(hidroximetil)aminometano-, modifica en el mismo sentido el estado ácido-base en sangre, líquido cefalorraquídeo y, por lo tanto, en sistema nervioso central, logrando el objetivo de corregir la acidosis, sin introducir secuelas neurológicas. Para demostrar lo expuesto anteriormente, se trabajó con dos grupos de perros que fueron anestesiados y ventilados mecánicamente. A un grupo se le infundió bicarbonato de sodio intravenoso y al otro THAM por la misma vía. Se midieron los siguientes parámetros ácido-base en sangre arterial, venosa y líquido cefalorraquídeo; pH, presión parcial de dióxido de carbono, bicarbonato real, exceso de bases y THAM en el líquido, con un método que desarrollamos para tal fin