Posterior reversible encephalopathy syndrome in critical COVID-19 patients: Report of 2 cases.

Posterior reversible encephalopathy syndrome is an acute neurological disorder characterized by variable symptoms and radiological images characteristic of vasogenic parietal-occipital edema. It is associated with clinical conditions such as high blood pressure, infection/sepsis, or cytotoxic/immunosuppressive drugs, among others. It is characterized pathophysiologically by endothelial damage with breakdown of blood-brain barrier, cerebral hypoperfusion, and vasogenic edema. The cases are presented on 2 critical COVID-19 patients who were admitted to pneumonia requiring mechanical ventilation and who, after removing sedation, developed acute and reversible neurological symptoms consisting of epilepsy and encephalopathy, associated with hyperintense subcortical lesions on brain magnetic resonance imaging compatible with posterior reversible encephalopathy syndrome. SARS-CoV-2 coronavirus would activate an inflammatory response that would damage brain endothelium. It could be triggered by cytokine release, as well as by direct viral injury, given that endothelium expresses ACE2 receptors. It could explain the possible association between posterior reversible encephalopathy syndrome and COVID-19.

Síndrome de encefalopatía posterior reversible en pacientes críticos COVID-19: reporte de 2 casos / Posterior reversible encephalopathy syndrome in critical COVID-19 patients: Report of 2 cases

El síndrome de encefalopatía posterior reversible es un trastorno neurológico agudo caracterizado por una sintomatología variable e imágenes radiológicas características de edema vasogénico parietooccipital. Está asociado a condiciones clínicas como hipertensión arterial, infección/sepsis o fármacos citotóxicos/inmunosupresores, entre otros. Se caracteriza fisiopatológicamente por daño endotelial con rotura de la barrera hematoencefálica, hipoperfusión cerebral y edema vasogénico. Presentamos 2 casos de pacientes críticos COVID-19 que ingresaron por neumonía con necesidad de ventilación mecánica y que tras retirar la sedación desarrollaron clínica neurológica aguda y reversible consistente en epilepsia y encefalopatía, asociada a lesiones subcorticales hiperintensas en la resonancia magnética cerebral compatibles con síndrome de encefalopatía posterior reversible. El coronavirus SARS-CoV-2 activaría una respuesta inflamatoria que produciría daño en el endotelio cerebral. Este último podría ser desencadenado por la liberación de citocinas, así como por una lesión viral directa, dado que el endotelio expresa receptores ACE2. Esto podría explicar la posible asociación entre el síndrome de encefalopatía posterior reversible y la COVID-19.(AU)

Posterior reversible encephalopathy syndrome is an acute neurological disorder characterized by variable symptoms and radiological images characteristic of vasogenic parietal-occipital edema. It is associated with clinical conditions such as high blood pressure, infection/sepsis, or cytotoxic/immunosuppressive drugs, among others. It is characterized pathophysiologically by endothelial damage with breakdown of blood-brain barrier, cerebral hypoperfusion, and vasogenic edema. The cases are presented on 2 critical COVID-19 patients who were admitted to pneumonia requiring mechanical ventilation and who, after removing sedation, developed acute and reversible neurological symptoms consisting of epilepsy and encephalopathy, associated with hyperintense subcortical lesions on brain magnetic resonance imaging compatible with posterior reversible encephalopathy syndrome. SARS-CoV-2 coronavirus would activate an inflammatory response that would damage brain endothelium. It could be triggered by cytokine release, as well as by direct viral injury, given that endothelium expresses ACE2 receptors. It could explain the possible association between posterior reversible encephalopathy syndrome and COVID-19.(AU)

[Posterior reversible encephalopathy syndrome in critical COVID-19 patients: Report of 2 cases]. / Síndrome de encefalopatía posterior reversible en pacientes críticos COVID-19: reporte de 2 casos.

Posterior reversible encephalopathy syndrome is an acute neurological disorder characterized by variable symptoms and radiological images characteristic of vasogenic parietal-occipital edema. It is associated with clinical conditions such as high blood pressure, infection/sepsis, or cytotoxic/immunosuppressive drugs, among others. It is characterized pathophysiologically by endothelial damage with breakdown of blood-brain barrier, cerebral hypoperfusion, and vasogenic edema.The cases are presented on 2 critical COVID-19 patients who were admitted to pneumonia requiring mechanical ventilation and who, after removing sedation, developed acute and reversible neurological symptoms consisting of epilepsy and encephalopathy, associated with hyperintense subcortical lesions on brain magnetic resonance imaging compatible with posterior reversible encephalopathy syndrome.SARS-CoV-2 coronavirus would activate an inflammatory response that would damage brain endothelium. It could be triggered by cytokine release, as well as by direct viral injury, given that endothelium expresses ACE2 receptors. It could explain the possible association between posterior reversible encephalopathy syndrome and COVID-19.

Factores perioperatorios que contribuyen a la aparición de dolor o náuseas y vómitos postoperatorios en cirugía laparoscópica ambulatoria / Perioperative factors that contribute to postoperative pain and/or nausea and vomiting in ambulatory laparoscopic surgery

Introducción: Tanto el dolor como las náuseas y vómitos postoperatorios constituyen condicionantes principales del tiempo y la calidad de la recuperación en cirugía laparoscópica. Objetivo: Determinar los factores perioperatorios que contribuyen a la aparición de dolor y de náuseas y vómitos postoperatorios en cirugía laparoscópica ambulatoria. Materiales y métodos: Estudio prospectivo de una cohorte de 297 pacientes intervenidos mediante cirugía laparoscópica ambulatoria. Como variables de estudio se consideraron: a) factores preoperatorios, incluyendo medicación habitual y riesgo anestésico; b) intraoperatorios, entre otros tiempos quirúrgico y anestésico, fármacos y presión de neumoperitoneo y c) postoperatorios, como complicaciones mayores o menores y tiempos de recuperación. Como variables dependientes se consideraron los síntomas postoperatorios náuseas, vómitos y dolor. Resultados: Considerando como variable combinada la aparición de náuseas, vómitos o dolor moderado/severo según una escala visual analógica, presentaron uno o más de estos síntomas el 58,7% de los pacientes (IC 95%: 52,8-64,4). Mediante regresión logística, las variables asociadas a la aparición de síntomas fueron: sexo femenino (OR: 3,4), tiempo de espera previo a quirófano superior a 45 min (OR: 4,9) y ausencia de profilaxis antiemética (OR: 12,2). Conclusiones: En pacientes operados mediante cirugía laparoscópica ambulatoria, uno de cada 4presenta náuseas y vómitos postoperatorios y la mitad presentan dolor de intensidad moderada antes del alta. Considerando globalmente la aparición de dolor o náuseas y vómitos postoperatorios, estos síntomas afectan a más de la mitad de los pacientes y son más frecuentes en mujeres y en quienes más tardan en acceder al quirófano

Introduction: Both postoperative pain and postoperative nausea and vomiting are major factors that determine the time and quality of recovery in laparoscopic surgery. Objective: To determine the perioperative factors that contribute to the appearance of postoperative pain and postoperative nausea and vomiting in outpatient laparoscopic surgery. Material and methods: A prospective study was conducted on a cohort of 297 patients undergoing laparoscopic ambulatory surgery. A record was made of preoperative factors (usual medication, anaesthetic risk, etc.), intraoperative (surgical and anaesthetic times, drugs, CO2 pressure, etc.), and postoperative factors (major and minor complications, recovery times, etc.). As dependent variables, the postoperative symptoms considered were, nausea, vomiting, and/or postoperative pain. Results: Considering as a combined variable the occurrence of níusea, vomiting or moderate/severe pain (4 or more points on a visual analogue scale), one or more of these symptoms occurred in 58.7% of the patients (95% CI: 52.8-64.4). Using a logistic regression, the variables associated with the appearance of symptoms were: female gender (OR: 3.4), waiting time over 45minutes prior to surgery (OR: 4.9) and no anti-emetic prophylaxis (OR: 12.2). Conclusions: In patients undergoing ambulatory laparoscopic surgery, one in 4had postoperative nausea and vomiting, and approximately half of moderate-intensity pain before discharge. Considering the overall the occurrence of pain and/or postoperative níusea and vomiting, these symptoms affect more than half of the patients being operated on, and are more frequent in women and in those who have to wait to access the operating room

Perioperative factors that contribute to postoperative pain and/or nausea and vomiting in ambulatory laparoscopic surgery. / Factores perioperatorios que contribuyen a la aparición de dolor o náuseas y vómitos postoperatorios en cirugía laparoscópica ambulatoria.

INTRODUCTION: Both postoperative pain and postoperative nausea and vomiting are major factors that determine the time and quality of recovery in laparoscopic surgery. OBJECTIVE: To determine the perioperative factors that contribute to the appearance of postoperative pain and postoperative nausea and vomiting in outpatient laparoscopic surgery. MATERIAL AND METHODS: A prospective study was conducted on a cohort of 297 patients undergoing laparoscopic ambulatory surgery. A record was made of preoperative factors (usual medication, anaesthetic risk, etc.), intraoperative (surgical and anaesthetic times, drugs, CO2 pressure, etc.), and postoperative factors (major and minor complications, recovery times, etc.). As dependent variables, the postoperative symptoms considered were, nausea, vomiting, and/or postoperative pain. RESULTS: Considering as a combined variable the occurrence of níusea, vomiting or moderate/severe pain (4 or more points on a visual analogue scale), one or more of these symptoms occurred in 58.7% of the patients (95% CI: 52.8-64.4). Using a logistic regression, the variables associated with the appearance of symptoms were: female gender (OR: 3.4), waiting time over 45minutes prior to surgery (OR: 4.9) and no anti-emetic prophylaxis (OR: 12.2). CONCLUSIONS: In patients undergoing ambulatory laparoscopic surgery, one in 4had postoperative nausea and vomiting, and approximately half of moderate-intensity pain before discharge. Considering the overall the occurrence of pain and/or postoperative níusea and vomiting, these symptoms affect more than half of the patients being operated on, and are more frequent in women and in those who have to wait to access the operating room.

The fourth Mexican consensus on Helicobacter pylori. / IV consenso mexicano sobre Helicobacter pylori.

Important advances have been made since the last Mexican consensus on the diagnosis and treatment of Helicobacter pylori (H. pylori) infection was published in 2007. Therefore, the Asociación Mexicana de Gastroenterología summoned 20 experts to produce "The Fourth Mexican Consensus on Helicobacter pylori". From February to June 2017, 4 working groups were organized, a literature review was performed, and 3 voting rounds were carried out, resulting in the formulation of 32 statements for discussion and consensus. From the ensuing recommendations, it was striking that Mexico is a country with an intermediate-to-low risk for gastric cancer, despite having a high prevalence of H. pylori infection. It was also corroborated that peptic ulcer disease, premalignant lesions, and histories of gastric cancer and mucosa-associated lymphoid tissue lymphoma should be considered clear indications for eradication. The relation of H. pylori to dyspeptic symptoms continues to be controversial. Eradication triple therapy with amoxicillin, clarithromycin, and a proton pump inhibitor should no longer be considered first-line treatment, with the following 2 options proposed to take its place: quadruple therapy with bismuth (proton pump inhibitor, bismuth subcitrate, tetracycline, and metronidazole) and quadruple therapy without bismuth (proton pump inhibitor, amoxicillin, clarithromycin, and metronidazole). The need for antimicrobial sensitivity testing when 2 eradication treatments have failed was also established. Finally, the promotion of educational campaigns on the diagnosis and treatment of H. pylori for both primary care physicians and the general population were proposed.

Indicación Farmacéutica para el estreñimiento en pacientes con diabetes e hipertensión arterial / Pharmaceutical indication for constipation in patients with diabetes and blood hypertension

Introducción: El estreñimiento en pacientes con hipertensión arterial o diabetes es un motivo frecuente de consulta al farmacéutico. La indicación farmacéutica no debe interferir con la medicación habitual de estos pacientes. Objetivos: Formular recomendaciones sobre indicación farmacéutica a pacientes con diabetes y/o hipertensión arterial que acuden a la oficina de farmacia solicitando tratamiento farmacológico para el estreñimiento. Material y métodos: Mediante revisión sistemática de Guías de Práctica Clínica sobre abordaje del estreñimiento, se han elaborado recomendaciones sobre indicación farmacéutica a pacientes con diabetes y/o hipertensión arterial que acuden a la oficina de farmacia solicitando tratamiento farmacológico. Tras diseñar una estrategia de búsqueda, se seleccionaron las fuentes bibliográficas y se llevó a cabo la recogida de información. La búsqueda bibliográfica se realizó en los siguientes recursos web: Medline, GuíaSalud, National Guideline Clearinghouse, Canadian Medical Association Infobase, Scottish Intercollegiate Guidelines Network, Australia’s Clinical Practice Guidelines Portal, Trip Database y National Health Service Evidence. Como fuentes complementarias, se consultó UpToDate, Base de Datos BOT plus 2.0 y un tratado de Farmacología Humana. Resultados: Las recomendaciones se refieren al manejo del estreñimiento idiopático no complicado en pacientes sin síntomas de alarma e incluyen, como tratamiento de primera línea, el consumo de fibra o de agentes formadores de masa. En pacientes que no toleran los laxantes formadores de masa o responden mal a suplementos de fibra, se recomienda el uso de laxantes osmóticos. Por último, si no hay una respuesta satisfactoria, las recomendaciones incluyen los laxantes estimulantes. En pacientes hipertensos, debe tenerse en cuenta que el hidróxido de magnesio presenta potenciales interacciones con algunos fármacos antihipertensivos. Conclusión: La indicación farmacéutica incluye, como tratamiento de primera línea, suplementos de fibra o agentes formadores de masa. En quienes no los toleran o no responden satisfactoriamente, pueden recomendarse laxantes osmóticos o estimulantes

Introduction: Constipation in patients with arterial hypertension or diabetes is a frequent reason for consulting the pharmacist. The pharmaceutical indication should not interfere with the usual medication of these patients. Objectives: To make recommendations on pharmaceutical indication for patients with diabetes and / or hypertension who come to the pharmacy seeking pharmacological treatment for constipation. Material and methods: Through the systematic review of Clinical Practice Guidelines on the treatment of constipation, have been made recommendations on the pharmaceutical indication for patients with diabetes and/or hypertension who come to the pharmacy seeking pharmacological treatment. After having designed a search strategy, bibliographic sources were selected and it was carried out a data collection. The bibliographic search was done in the following web resources: Medline, GuíaSalud, National Guideline Clearinghouse, Canadian Medical Association Infobase, Scottish Intercollegiate Guidelines Network, Australia’s Clinical Practice Guidelines Portal, Trip Database and National Health Service Evidence. As complementary sources of data, UpToDate, Database BOT plus 2.0 and a treaty of Human Pharmacology were consulted. Results: Recommendations relate to the management of uncomplicated idiopathic constipation in patients without symptoms of alarm and include, as first-line treatment, the consumption of fiber or mass-forming agents. In patients who do not tolerate mass-forming laxatives or respond poorly to fiber supplements, the use of osmotic laxatives is recommended. Finally, if no satisfactory response, recommendations include stimulant laxatives. In hypertensive patients, it should be taken into account that magnesium hydroxide has potential interactions with some antihypertensive drugs. Conclusion: The pharmaceutical indication includes, as a first-line treatment, fiber supplements or mass-forming agents. In those who do not tolerate or do not respond satisfactorily, osmotic or stimulant laxatives may be recommended

Role of hydrogen sulfide in the pain processing of non-diabetic and diabetic rats.

Hydrogen sulfide (H2S) is a gasotransmitter endogenously generated from the metabolism of L-cysteine by action of two main enzymes called cystathionine ß-synthase (CBS) and cystathionine γ-lyase (CSE). This gas has been involved in the pain processing and insulin resistance produced during diabetes development. However, there is no evidence about its participation in the peripheral neuropathy induced by this metabolic disorder. Experimental diabetes was induced by streptozotocin (50mg/kg, i.p.) in female Wistar rats. Streptozotocin injection increased formalin-evoked flinching in diabetic rats as compared to non-diabetic rats after 2 weeks. Peripheral administration of NaHS (an exogenous donor of H2S) and L-cysteine (an endogenous donor of H2S) dose-dependently increased flinching behavior in diabetic and non-diabetic rats. Contrariwise, hydroxylamine (HA, a CBS inhibitor) and DL-propargylglycine (PPG, a CSE inhibitor) decreased formalin-induced nociceptive behavior in both experimental groups. In addition, an ineffective dose of HA and PPG partially prevented the L-cysteine-induced hyperalgesia in diabetic and non-diabetic rats. Interestingly, HA and PPG were three order of magnitude more potent in diabetic rats respect to non-diabetic rats, whereas NaHS was ten times more potent in the streptozotocin-diabetic group. Nine to 11 weeks after diabetes induction, tactile allodynia was observed in the streptozotocin-injected rats. On this condition, subcutaneous administration of PPG or HA reduced tactile allodynia in diabetic rats. Paradoxically, H2S levels were decreased in nerve sciatic, dorsal root ganglion and spinal cord, but not paw nor blood plasma, during diabetes-associated peripheral neuropathy development. Collectively, results suggest that H2S synthesized by CBS and CSE participate in formalin-induced nociception in diabetic and non-diabetic rats, as well as; in tactile allodynia in streptozotocin-injected rats. In addition, data seems to indicate that diabetic rats are more sensible to H2S-induced hyperalgesia than normoglycemic rats.

Identification of the Na+/H+ exchanger 1 in dorsal root ganglion and spinal cord: its possible role in inflammatory nociception.

mRNA and protein presence of Na+/H+ exchanger (NHE) 1 (NHE1) and 5 (NHE5) in dorsal root ganglion (DRG) and dorsal spinal cord as well as its possible role in three inflammatory nociception tests were determined. Local peripheral ipsilateral, but not contralateral, administration of NHE inhibitors 5-(N,N-dimethyl)amiloride hydrochloride (DMA, 0.3-30 microM/paw), 5-(N-ethyl-N-isopropyl)amiloride (EIPA, 0.3-30 microM/paw) and amiloride (0.1-10 microM/paw) significantly increased flinching but not licking behavior in the capsaicin and 5-HT tests. Moreover, DMA and EIPA (0.03-30 microM/paw) as well as amiloride (0.1-1 microM/paw) augmented, in a dose-dependent manner, 0.5% formalin-induced flinching behavior during phase II but not during phase I. Reverse transcription-polymerase chain reaction showed the expression of NHE1 and NHE5 in DRG and dorsal spinal cord. Western blot analysis confirmed the presence of NHE1 in DRG and spinal cord. Moreover, NHE5 was expressed in dorsal spinal cord, but not in DRG where a 45 kDa truncated isoform of NHE5 was identified. Collectively, these data suggest that NHE1, but not NHE5, plays an important role reducing inflammatory pain in rats.

Oral pharmacokinetics of meloxicam in the rat using a high-performance liquid chromatography method in micro-whole-blood samples.

The pharmacokinetics of meloxicam, a potent analgesic and antiinflammatory drug used in several rheumatic diseases, has been studied in rats that received oral doses of 3.2, 5.6 or 10 mg/kg of meloxicam. Blood samples were obtained at selected times during 24 h after administration, and meloxicam concentrations were determined by a validated high-performance liquid chromatography (HPLC) method, using micro-whole-blood samples, developed in our laboratory. After administration of meloxicam, blood concentrations increased reaching a dose-dependent maximal concentration in about 2 h. Then, concentrations decayed with a half-life of 9 h. An increase in C(max) and AUC as a function of the dose was observed, and no statistically significant difference was observed in AUC/dose or C(max)/dose between doses. However, linearity could not be concluded because of the wide variability observed.

Use of receiver operating characteristic curves to assess the performance of a microdilution assay for determination of drug susceptibility of clinical isolates of Mycobacterium tuberculosis.

The aim of this study was to apply receiver operating characteristic (ROC) analysis to the microplate Alamar blue assay, a recently developed alternative for drug susceptibility testing of mycobacteria. As this is a quantitative assay, its performance can be determined by ROC analysis, in which the area under the ROC curve represents a summary of test performance (the higher the area, the better the test's performance). Sixty isolates of Mycobacterium tuberculosis were tested by the microcolorimetric assay against six twofold dilutions of streptomycin, isoniazid, rifampin, and ethambutol. For each isolate, the susceptibility pattern was simultaneously established by the agar proportion method, the result of which represented the gold standard value for the ROC analysis. The critical concentration, area under the curve, and P value for each drug were determined by ROC curve analysis. The results of the assay were obtained in an average of 8 days of incubation. The performance of the assay was excellent for all four drugs: the area under the curves was >0.97, the P values were 0.000, and sensitivity was 94%, specificity 97%, predictive value for resistance >/=92%, predictive value for susceptibility 97%, and test efficiency 97%. According to ROC analysis, the microplate Alamar blue assay is a reliable method for determination of drug-susceptibility. Rapidity and cost efficiency are two additional qualities that make this test an excellent alternative for the drug susceptibility testing of Mycobacterium tuberculosis. The ROC curve analysis is a robust statistical approach for evaluating the performance of new quantitative methods for determination of drug sensitivity of Mycobacterium tuberculosis isolates.

Participation of the nitric oxide-cyclic GMP-ATP-sensitive K(+) channel pathway in the antinociceptive action of ketorolac.

The involvement of nitric oxide (NO), cyclic GMP and ATP-sensitive K(+) channels in the antinociceptive effect of ketorolac was assessed using the formalin test in the rat. Local administration of ketorolac in a formalin-injured paw produced a dose-dependent antinociceptive effect due to a local action, as drug administration in the contralateral paw was ineffective. Pretreatment of the injured paw with N(G)-L-nitro-arginine methyl ester (L-NAME, an NO synthesis inhibitor), 1H-(1,2,4)-oxadiazolo(4,2-a)quinoxalin-1-one (ODQ, a soluble guanylyl cyclase inhibitor) or glibenclamide (an ATP-sensitive K(+) channel blocker) prevented ketorolac-induced antinociception. However, pretreatment with saline or N(G)-D-nitro-arginine methyl ester (D-NAME) did not block antinociception. Local administration of S-nitroso-N-acetylpenicillamine (SNAP, an NO donor) was inactive by itself, but increased the effect of ketorolac. The present results suggest that the antinociceptive effect of ketorolac involves activation of the NO-cyclic GMP pathway, followed by an opening of ATP-sensitive K(+) channels at the peripheral level.

Interleukin levels in cerebrospinal fluid from children with neurocysticercosis.

No information about the levels of pro-inflammatory interleukins has been described in children with neurocysticercosis (NCC). The levels of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-5, IL-6, and IL-12 in the cerebrospinal fluid from children with NCC were determined by enzyme-linked immunosorbent assay (ELISA). Twelve children with NCC, six with active and six with inactive disease, and six children without NCC were studied. TNF-alpha was undetectable in CSF from controls and five children with inactive NCC, whereas the levels were significantly higher (median 22.1 pg/ml; P = 0.008) in all children with active NCC. Levels of IL-6 were low in active and inactive NCC patients but two subjects with active subarachnoid disease had high levels. IL-5 and IL-12 were not detected. This study shows that high levels of TNF-alpha are present in CSF from children with active NCC. IL-6 levels are higher when infection occurs in the subarachnoid space.

Sildenafil increases diclofenac antinociception in the formalin test.

The antinociceptive activity of an inhibitor of phosphodiesterase 5, alone or combined with diclofenac, was assessed in the formalin test. Local administration of diclofenac produced a significant antinociception in both phases of the formalin test in female Wistar rats. In contrast, 1-[4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [3,4-d]pyrimidin-5-yl)phenylsulfonyl]-4-methyl piperazine (sildenafil, an inhibitor of phosphodiesterase 5) produced significant antinociception, only during the second phase of the formalin test. Non-effective doses of sildenafil (25-100 microg/paw) significantly increased the antinociceptive effect of an inactive dose of diclofenac (25 microg) in both phases of the test. The antinociception produced by the drugs alone or the combination was due to a local action, as its administration in the contralateral paw was ineffective. Since sildenafil is a potent and selective inhibitor of phosphodiesterase 5, our results suggest that this drug produced its antinociceptive activity, and increased that of diclofenac, probably through the inhibition of cyclic GMP degradation.

Secretion antigens of Mycobacterium tuberculosis: a comparison between a reference strain and seven wild isolates.

BACKGROUND: This study was carried out with the aim of detecting possible differences between proteins secreted by fresh wild isolates of Mycobacterium tuberculosis and from a reference strain of this microorganism, H37Rv TMCC 102. MATERIALS AND METHODS: This reference strain of M. tuberculosis has been in our laboratory for over 10 years, where it has been maintained by serial subcultures in PBY and Lowenstein-Jensen media. Patterns of protein secretion and recognition by sera derived from both tuberculosis patients and normal individuals were analyzed by electrophoresis and Western blotting. RESULTS: No major qualitative differences were observed among the several strains studied with respect to protein patterns or recognition of these proteins by test sera. Normal sera were found to react with almost all antigens recognized by tuberculosis sera, but with less intensity. However, a small protein of 14.5 kDa, secreted by both the wild and reference strains of M. tuberculosis, was recognized by 32 of the 40 tuberculous patient sera tested (80%), and was not recognized by any of the 40 serum samples derived from healthy individuals. CONCLUSIONS: This small protein seems to be a potentially important antigen for the serological diagnosis of tuberculosis and/or for use in the follow-up of patients who received treatment.

Effects of toxin A from Clostridium difficile on mast cell activation and survival.

Toxins A and B from Clostridium difficile are the main cause of antibiotic-associated diarrhea and pseudomembranous colitis. They cause fluid accumulation, necrosis, and a strong inflammatory response when inoculated in intestinal loops. Since mast cells are a rich source of inflammatory mediators, abundant in the gut, and known to be involved in C. difficile-induced enteritis, we studied the in vitro effect of toxin A on isolated mast cells. Normal rats sensitized by infection with Nippostrongilus brasiliensis were used to isolate peritoneal mast cells (PMC). PMC from naive rats were stimulated with calcium ionophore A23187 as a model of antigen-independent activation, and PMC from sensitized rats were stimulated with N. brasiliensis antigens to study immunoglobulin E-dependent mast cell activation. After 4 h, toxin A did not induce release of nitric oxide or histamine in naive PMC. However, 10 ng of toxin per ml caused a significant release of tumor necrosis factor alpha (TNF-alpha). In contrast, 1 microg of toxin per ml inhibited antigen or A23187-induced histamine release by PMC. Toxin A at 1 microg/ml for 4 h caused disruption of actin which aggregated in the cytoplasm and around the nucleus. After 24 h, chromatin condensation, cytoplasmic blebbing, and apoptotic-like vesicles were observed; DNA fragmentation was documented also. These results suggest that mast cells may participate in the initial inflammatory response to C. difficile infection by releasing TNF-alpha upon interaction with toxin A. However, longer exposure to toxin A affects the release of inflammatory mediators, perhaps because of the alteration of the cytoskeleton and induction of apoptosis. The impaired functions and survival of mast cells by C. difficile toxin A could hamper the capacity of these cells to counteract the infection, thus prolonging the pathogenic effects of C. difficile toxins.