Cortisol y dehidroepiandrosterona nocturnos como marcadores pronósticos en pacientes críticos / Nocturnal cortisol and dehydroepiandrosterone like prognostic markers in critical patients

El cortisol plasmático guarda correlación con la severidad y duración del estado crítico, y el papel de la Dehidroepiandrosterona sulfato (DHEA-S) no ha sido identificado claramente. El paciente crítico muestra una activación máxima inicial del eje suprarrenal, si la situación crítica se prolonga, se puede producir una insuficiencia suprarrenal relativa. Midiendo cortisol y DHEA-S durante la noche de las 24 primeras horas críticas se podría hacer más evidente esta insuficiencia resultando una mejor correlación entre estas hormonas, APACHE II y mortalidad. Diseño: Estudio observacional en pacientes críticos de la UTI del Hospital de Urgencia Asistencia Pública. Cuarenta y ocho (48) pacientes (30 hombres y 18 mujeres) sin antecedentes de: insuficiencia suprarrenal, uso de fenitoína, anticonvulsivantes, rifampicina, ketoconazol, corticosteroides, síndrome de Cushing, patología pituitaria, daño hepático crónico, insuficiencia renal crónica, alcoholismo activo crónico o readmisiones. EL APACHE II fue evaluado al ingreso. Cortisol y DHEA-S fueron medidos a las 00.00 de las primeras 24 h de su ingreso a UTI. Resultados: EL APACHE II (25,1±6,7 contra 16,3±7, p=0,001) y edad (59,5±15,8 contra 44,4±18,1, p 0,011) fueron significativamente más elevados en los fallecidos. En los fallecidos el cortisol mostró una tendencia a niveles más elevados. El DHEA-S mostró niveles considerablemente más altos en los sobrevivientes (5450,9±3824,0 contra 2980,3±2159,3 p= 0,03) junto como el índice DHEA-S/cortisol (12,66±14,19 contra 3,91±4,06, p= 0,004). Conclusiones: La tendencia a niveles más altos de cortisol nocturno observado en las 24 primeras horas induce para pensar que la insuficiencia suprarrenal relativa no desempeñaría un papel en las 24 primeras horas del estado crítico. Los niveles de DHEA-S y el índice DHEA-S/Cortisol son marcadores de sobrevida en nuestra población estudiada.

Contribution of the gasoline distribution cycle to volatile organic compound emissions in the metropolitan area of Mexico City.

Gasoline distribution in the metropolitan area of Mexico City (MAMC) represents an area of opportunity for the abatement of volatile organic compound (VOC) emissions. The gasoline distribution in this huge urban center encompasses several operations: (1) storage in bulk and distribution plants, (2) transportation to gasoline service stations, (3) unloading at service stations' underground tanks, and (4) gasoline dispensing. In this study, hydrocarbon (HC) emissions resulting from breathing losses in closed reservoirs, leakage, and spillage from the operations just listed were calculated using both field measurements and reported emission factors. The results show that the contribution of volatile HC emissions due to storage, distribution, and sales of gasoline is 6651 t/year, approximately 13 times higher than previously reported values. Tank truck transportation results in 53.9% of the gasoline emissions, and 31.5% of emissions are generated when loading the tank trucks. The high concentration of emissions in the gasoline transportation and loading operations by tank trucks has been ascribed to (1) highly frequent trips from distribution plant to gasoline stations, and vice versa, to cope with excessive gasoline sales per gasoline station; (2) low leakproofness of tank trucks; and (3) poor training of employees. In addition, the contribution to HC evaporative and exhaust emissions from the vehicles of the MAMC was also evaluated.

Desinfección de tubos endotraqueales / Desinfection of endotraqueal tubes

Se realizó estudios bacteriológicos de tubos endotraqueales tipo Rush, en los que utilizaron soluciones antisépticas, de las cuales solo la solución de hipoclorito de sodio al 3 por ciento fue la única que resultó adecuada para su uso, comprobada en estudios anteriores. En el presente estudio se comprueba que existe otra solución antiséptica que tiene aplicabilidad para la antisépsia de tubos endotraqueales de caucho mineralizado tipo Rush que se vuelven a utilizar en varias oportunidades. Se utilizó como solución antiséptica yodopovidona, con hisopeado post-intubación post-lavado, cepillado e inmersión en yodopovidona, inmediatamente estos hisopeados se pusieron a caldo de cultivo de soya tripdticasa para observar el desarrollo bacteriológico

Pharmacological aspects of mouse hind-paw oedema induced by Lachesis muta rhombeata venom.

Pharmacological aspects of mouse hind-paw oedema induced by subplantar injections of Lachesis muta rhombeata (LMR) venom were investigated. The oedema induced by subplantar injections of 10 to 50 ng/g of LMR venom is dose dependent, with onset, peak and duration at 30, 60 and 180 min, respectively. Subplantar injection of 30 ng/g of Bothrops jararaca (BJ) venom induced oedema that has the same intensity as 30 ng/g of LMR venom but lasts for more than 4 h suggesting different time course. Systemic effects or haemorrhage were not observed with doses less than 50 ng/g. Oedema is not due to the presence of oedematogenic amines since dialysis did not change the oedema induced by 30 ng/g of LMR venom. Part of the oedema induced by LMR venom is due to a thermolabile fraction since pre-heating the venom at 100 degrees C for 15 min induced a significant reduction (56.19 +/- 6.8%) of the oedematogenic activity. The oedema induced by LMR venom is possibly induced by release of a pharmacological active substance at the site of injection. Histamine, arachidonate metabolites, nitric oxide and serotonin may play important roles in the oedematogenic effect of LMR venom since pre-treatment of mice with pyrilamine, indomethacin, dexamethasone, L-NAME and methysergide induced a significant reduction (49.86 +/- 10%; 51.06 +/- 5.9%; 77.66 +/- 3.6%; 73.30 +/- 6.1% and 93.77 +/- 2.8%, respectively) of the oedema formation. The present results demonstrate that the oedema induced by LMR and BJ venoms may be triggered and maintained by different pharmacological mechanisms. Since methysergide and L-NAME were the most active inhibitors of the oedema we can suggest that a link between serotonin release by the venom and a NO synthase activation may be an important step in the oedema formation induced by LMR venom.

Sinergismo atracurio - alcuronio / Atracurio - alcuronio synergy

Se estudió la relajación muscular obtenida con la asociación de atracurio-alcuronio en 21 pacientes de ambos sexos sometidos a cirugía general. El objetivo de este trabajo es evaluar la utilidad clínica de la asociación atracurio-alcuronio, basándonos en las investigaciones en vivo, que han señalado la existencia de un sinergismo, cuando ambas drogas se usan en forma combinada. Se realizó la premedicación con atropina 0.01 mg/kp, thalamonal 0.02 ml/kp, se indujo con tiopental sódico (5-7 mg/kp) y facilitando la intubación orotraqueal con succinilcolina a razón de 1 mg/kp. Inmediatamente pasado su efecto se inyecta la combinación atracurio (0.2 mg/kp) y alcuronio (0.1 mg/kp) como dosis inicial

Single-step purification of crotapotin and crotactine from Crotalus durissus terrificus venom using preparative isoelectric focusing.

We describe the isolation of crotoxin, a presynaptic B-neurotoxin, as well as its subunits B (crotactine) and A (crotapotin) from lyophilized Crotalus durissus terrificus venom by a single-step preparative isoelectric focusing procedure. From 98 mg of dried venom protein 20.1 mg of crotactine and 13.1 mg of crotapotin were recovered in the first step of focalization and 4.2 mg in a second run. These values correspond to 35.7% of the total venom protein applied. Crotactine separated in the 9.3-7.0 pH range (tubes 1-6) and crotapotin in the 1.8-2.8 pH range (tubes 15-19) and both were homogeneous by SDS-PAGE and N-terminal amino acid analysis. Crotactine, a 12-kDA protein, presented hemolytic and phospholipase A2 activity. Thus, using isoelectric focusing we simultaneously purified both toxins in high yields. This method can be used as an alternative for the purification and characterization of proteins from other snake venoms under conditions in which biological activity is retained.

Single-step purification of crotapotin and crotactine from Crotalus durissus terrificus venom using preparative isoeletric focusing

We describe the isolation of crotoxin, a presynaptic B-neurotoxin, as well as its subunits B (crotactine) and A (crotapotin) from lyophilized Crotalus durissus terrificus venom by a single-step preparative isoelectric focusing procedure. From 98 mg of dried venom protein 20.1 mg of crotactine and 13.1 mg of crotapotin were recovered in the first step of focalization and 4.2 mg in a second run. These values correspond to 35.7 per cent of the total venom protein applied. Crotactine separated in the 9.3-7.0 pH range (tubes 1-6) and crotapotin in the 1.8-2.8 pH range (tubes 15-19) and both were homogeneous by SDS-PAGE and N-terminal amino acid analysls. Crotactine, a 12-kDa protein, presented hemolytic and phospholipase A2 activity. Thus, using isoelectric focusing we simultaneously purified both toxins in high yields. This method can be used as an altemative for the purification and characterization of proteins from other snake venoms under conditions in which biological activity is retained.

Purification and partial characterization of a thrombin-like/gyroxin enzyme from bushmaster (Lachesis muta rhombeata) venom.

The acidic coagulating enzyme of the L. m. rhombeata venom was purified to homogeneity using one step on preparative isoelectric focusing followed by gel permeation on a high performance liquid chromatography system. The enzyme focused with pIs 3.1-5.0 and had a molecular mass of 47,000 mol. wt as determined by high performance liquid gel-filtration chromatography and about 45,000 mol. wt as judged by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis. The enzyme is a glycoprotein containing sialic acid and 12.4% of neutral carbohydrates. The 30 N-terminal amino acid sequence of the L. m. rhombeata protein shows 100% identity with L. m. muta gyroxin and considerable sequence homology with gyroxin and thrombin-related proteins. The enzyme exhibits strong N-p-tosyl-L-arginine methyl esterase activity, hydrolyses tripeptide nitroanilide derivatives weakly or not at all, and cleaves specifically the fibropeptide A (alpha-chain).

Polyamines as biomarkers of cervical intraepithelial neoplasia.

Polyamines (putrescine, spermidine and spermine) play critical roles in cell growth and transformation. Ornithine decarboxylase (ODC), key enzyme in polyamine biosynthesis, is considered a putative protooncogene crucial to the regulation of cell growth and transformation. Cancer patients have elevated levels of polyamines in their physiological fluids compared to normal counterparts. alpha-Difluoromethylornithine (DFMO), a specific suicide inhibitor of ODC, exhibits antitumor and antimetastasis activities, and displays effectiveness in many carcinogen-induced animal chemoprevention models. Therefore, we are using DFMO in a chemoprevention trial for cervical intraepithelial neoplasia grade III (CIN III), and evaluating patients for changes in polyamine metabolism as an intermediate marker of DFMO effect. A preliminary study showed that several milligrams of abnormal cervical biopsy tissue contained detectable levels of ODC activity and polyamines. Additionally, the presence of cadaverine suggested bacterial contamination of these tissues. For this reason, normal and abnormal biopsies collected during colposcopy were rinsed prior to frozen storage. In most patients, abnormal tissue showed greater ODC activities and lower spermidine/spermine ratios than normal tissues. Patients are now being treated with de-escalating doses of DFMO (1-0.06 g/m2/day) for one month. To study the effect of DFMO in patients with CIN III, we are collecting blood and cervical tissue specimens to measure the following parameters: plasma DFMO, ornithine and arginine levels; plasma N1-acetylspermidine levels; erythrocyte (blood polyamine carrier) free polyamine levels; cervical tissue free polyamine levels; cervical tissue N1-acetylspermidine levels; and cervical tissue ODC activities. N1-acetylspermidine will be examined as this compound is known to exist primarily in tumor tissues, not in normal tissues. We therefore established a high-performance liquid chromatography method for N1-acetylspermidine. We expect to find that polyamines are effective markers in analyzing DFMO effects in this chemoprevention trial, thus functioning as pharmacodynamic parameters as well as biomarkers for transformation.

Functional and metabolic effects of bupivacaine and lidocaine in the perfused working rat heart.

The effects of bupivacaine (2.5, 5, 10, and 12.5 mg/L) and lidocaine (12.5, 25, 40, and 50 mg/L), on spontaneous heart rate, mean pressure development, cardiac output, and coronary flow were compared after 15 minutes' exposure in the isolated perfused working rat heart preparation. In addition, myocardial oxygen consumption, glucose utilization, lactate production, tissue content of glycogen, adenine nucleotides, and creatine phosphate content were measured. The relative potency of bupivacaine to lidocaine, calculated from slopes of regression equations, as indicated by the four mechanical variables and oxygen consumption, was 4.59. When the bupivacaine concentration was "normalized" using this value, bupivacaine and lidocaine showed indistinguishable effects on glucose utilization, lactate production, and tissue glycogen. Neither of the local anesthetics had any influence on energy charge or creatine phosphate content.