Tumores de colon de expansión lateral: características en nuestra población / Laterally spreading tumors: characteristics in our population

Introduction: Colorectal cancer is a rising disease worldwide. In Chile, it is the third leading cause of death associated to gastrointestinal cancer. Optimal preventive management requires surveillance of precursor lesions or early-stage tumors. Laterally spreading tumors (LST) are categorized as nonpolypoid colorectal neoplasms. Since there are no demographic data on these lesions in our country, the aim of our study was to describe the characteristics of LSTs based on our department’s data. Methods: We reviewed the department’s colonoscopy database from 1996 to 2006 to obtain clinical, endoscopic and histological data. We excluded patients with family history of polyposis, prior colorectal cancer and inflammatory bowel disease. Results: Out of 3713 colonoscopies performed, 364 (9.8 percent) adenoma cases were detected; 42 (1.2 percent) of them were catalogued as LSTs. Thirty-three LST patients had complete data and were included in the study. The gender proportion was similar between male and female. Ages ranged from 35 and 92 years (mean +/- SD 66.7 +/- 13.7). The tumor size ranged from 10 to 120 mm (mean +/- SD 28.2 +/- 28.3). According to distribution along the large bowel, 19 (57.5 percent) LSTs were located distally and 14 (42.5 percent) were proximal to the splenic flexure. Histology showed 26 adenomas (14 of them with high-grade dysplasia), 5 adenocarcinomas and 2 hyperplastic lesions. Conclusion: In Chile, LSTs are mainly found in the elderly. It is important to detect these lesions because most of them contain cancer or high-grade dysplasia. Therefore, during colonoscopy, we should focus not only on polypoid lesions, but also on flat lesions.

Introducción: El cáncer colorrectal es una enfermedad emergente a nivel mundial. En nuestro país es la tercera causa de muerte por cáncer del tubo digestivo. Un óptimo manejo preventivo implica la detección y tratamiento de las lesiones precursoras y los cánceres incipientes. Los tumores de expansión lateral (Laterally spreading tumors-LST) se consideran lesiones precursoras no polipoídeas. En Chile no existen datos demográficos de estas lesiones, por lo que el objetivo de este estudio es caracterizar los LST en nuestra población. Métodos: Revisamos la base de datos de las colonoscopias realizadas en nuestro Instituto desde 1996 al 2006, obteniendo datos clínicos y las características endoscópicas e histológicas. Excluimos los pacientes con historia de poliposis familiar, cáncer colorrectal y enfermedad inflamatoria intestinal. Resultados: De 3.713 colonoscopias, se detectaron 364 (9,8 por ciento) casos diagnosticados como adenoma, lesiones planas o LST, de los cuales 42 (1,2 por ciento) se catalogaron como LST. Sólo 33 pacientes con LST tenían disponible el estudio histológico. La proporción por género fue similar entre hombres (17) y mujeres (16). El rango de edad se distribuyó entre 35 y 92 años (promedio +/- DE 66,7 +/- 13,7); el tamaño tumoral fue de 10 a 120 mm (promedio +/- DE 28,2 +/- 28,3). De acuerdo a la distribución en el colon y recto, 19 (57,5 por ciento) LST se localizaron distales al ángulo esplénico y 14 (42,5 por ciento) proximales. El estudio histológico demostró 26 adenomas, 14 de los cuales presentaban displasia de alto grado, 5 adenocarcinomas y 2 lesiones hiperplásicas. Conclusión: En nuestra población los LST se presentan mayoritariamente en la tercera edad. Es importante la detección de estas lesiones, dado que en su mayoría contienen un cáncer o son adenomas con displasia de alto grado. Durante la colonoscopia no solamente debemos enfocarnos en los pólipos sino también en las lesiones planas.

Shunts portosistémicos espontáneos en pacientes con encefalopatía hepática / Spontaneous portal-systemic shunts in hepatic encephalopathy patients: preliminary experience

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome caused by hepatic dysfunction and portosystemic shunting of the intestinal blood. For HE patients nonresponsive to standard therapy, the presence of large spontaneous portal-systemic shunts can occasionally be the cause of the problem. Objective: To assess the prevalence of portal-systemic shunts in patients with cirrhosis and recurrent or persistent HE. Patients and Methods: Ten patients with liver cirrhosis were analyzed who repeatedly developed HE despite pharmacotherapy. Also, we studied seven control patients with cirrhosis and no HE, who were considered the control group. Results: Large spontaneous portal-systemic shunts were detected in all patients with HE and none in the control group (X2 13.1; P: 0.0003). If only splenorenal shunts are considered, the difference is also significant (X2 5.69; p: 0.017). Conclusion: Our study confirmed that the presence of large spontaneous portal-systemic shunts is frequent in patients with cirrhosis and recurrent or persistent HE.

La encefalopatía hepática (EH) es un síndrome neuropsiquiátrico causado por insuficiencia hepática o presencia de shunts portosistémicos (SPS) intra o extrahepáticos. En pacientes con EH refractaria a tratamiento médico habitual se ha planteado que la presencia de SPS podría ser la causa del problema. Objetivo: Evaluar la prevalencia de SPS espontáneos extrahepáticos en pacientes con cirrosis y EH recurrente o persistente. Pacientes y Métodos: Se evaluaron 10 pacientes con EH recurrentes o persistente. También, se estudiaron 7 pacientes con cirrosis y sin EH que se consideraron como grupo control. Resultados: Todos los pacientes con EH recurrente o persistente presentaron SPS; 7 presentaron shunts esplenorrenales espontáneos y 3 presentaron presencia de la vena umbilical recanalizada. Ningún paciente en el grupo control presentó SPS (X2 13,1; p: 0,0003). Si se considera sólo los shunts esplenorrenales, la diferencia también es significativa (X2 5,69; p: 0,017). Conclusión: En nuestros pacientes con cirrosis y EH recurrente o persistente fue frecuente la presencia de SPS espontáneos.

Hallazgos endoscópicos en pacientes ambulatorios referidos a endoscopia por síntomas digestivos altos / Endoscopic findings in ambulatory patients referred to endoscopy for upper digestive symptoms

Antecedentes: La realización de endoscopia como primer estudio de un paciente con dispepsia es muy controvertida. Objetivos: Conocer la frecuencia de patología orgánica en pacientes con dispepsia a quienes se les solicita endoscopia digestiva alta, tanto desde la atención primaria como desde los consultorios de especialidades. Métodos: Se analizó la base de datos de endoscopias de nuestro centro en el período 1999-2002. Los diagnósticos de cáncer se confirmaron histológicamente. Resultados: En 10.275 endoscopias practicadas en ese período, 1.488 fueron por dispepsia, 2.536 por síndrome ulceroso y 1.055 por reflujo gastroesofágico. En el grupo con dispepsia se encontró patología orgánica en un 33 por ciento, predominando la gastritis significativa y la esofagitis erosiva. La frecuencia de cáncer gástrico fue baja (0,1 por ciento) y sólo apareció en pacientes sobre 40 años y especialmente en mayores de 60. Lo mismo ocurrió en pacientes referidos por síndrome ulceroso y por reflujo gastroesofágico. Conclusiones: Solicitar endoscopia a pacientes con dispepsia está justificado porque un tercio de ellos tienen patologías de fácil y efectivo tratamiento. El acceso irrestricto a la endoscopia como screening de cáncer gástrico no parece en cambio ser útil en pacientes de menores de 60 años.

Background: The performance of upper digestive endoscopy as a first line study in patients with dyspepsia is highly controversial. Objectives: To investigate the frequency of organic diseases in dyspeptic patients referred from Primary Care centers or from Gastroenterology clinics for upper digestive endoscopy. Methods: The Endoscopy database of our unit was reviewed for the period 1999-2002. The endoscopic diagnosis of gastric cancer was confirmed by positive biopsies. Results: Out of 10.275 endoscopies performed in the study period, the reference diagnosis was: dyspepsia 1.488; ulcer syndrome 2.536 and gastroesophageal reflux 1.055. In the dyspepsia group, 33 percent of cases had some organic pathology, mainly gastritis and erosive esophagitis. The frequency of gastric cancer was low (0.1 percent) and it was found only in patients older than 40 years and specially older than 60 years. Similar results were found in patients referred for ulcer syndrome or gastroesophageal reflux. Conclusions: An upper digestive endoscopy in the initial work up of patients with dyspepsia seems to be acceptable one third of them present organic diseases with easy and effective therapies. On the other hand the irrestrictive acces to endoscopy as screening of gastric cancer does not seem to be useful in patients under 60 years.

Efectos de la infusión aguda de octreotido sobre la función renal en pacientes con cirrosis hepática e hipertensión portal / Effects of acute octreotide infusion on renal function in patients with cirrhosis and portal hypertension

Background: Octreotide is used in the treatment of acute variceal bleeding, based on its inhibitory effects of post-prandial splanchnic hyperemia and splanchnic venoconstriction. The consequences of these haemodynamic changes on renal circulation are not well known in cirrhotic patients. Aim: To evaluate the effects of acute octreotide administration on several parameters of renal function, including free water clearance, in patients with cirrhosis with or without ascites. Patients and Methods: Twenty cirrhotic patients, Child-Pugh A or B, with or without ascites, with esophageal varices, normal renal function and free of medications (vasoactive drugs or diuretics) were assigned to 2 different protocols. Protocol 1: 10 patients were randomized to receive octreotide or placebo, as a bolus followed by a continuous infusion. Glomerular filtration rate (GFR) and renal plasma flow (PRF) were measured, in basal conditions and during the drug or placebo administration. Protocol 2: 10 additional patients were randomized in the same way and free water clearance and urinary sodium excretion were again measured in the basal period and during the drug or placebo infusion. Results: After octreotide or placebo administration no significant changes were observed neither in GFR nor in PRF. The free water clearance decreased significantly during octreotide administration (3.12 ml/min±1.04 SE vs 0.88±0.39, p <.03). In both protocols no changes in mean arterial pressure were observed. Conclusions: Acute administration of octreotide to cirrhotic patients with portal hypertension, with or without ascites, did not produce any change in glomerular filtration rate or in estimated renal plasma blood flow. However the free water clearance decreased significantly. This effect, under chronic administration, could be clinically important and deserves further studies.

Time structure, temporal correlation and coherence of chemosensory impulses propagated through both carotid nerves in cats

In spontaneously breathing, pentobarbitone anesthetized cats, we recorded simultaneously the impulses in the chemosensory fibers of both carotid (sinus) nerves, to analyze the correlations between the frequencies of chemosensory discharges (f chi) and their activation ({df chi/dt}a) and deactivation ({df chi/dt}d) rates. We studied the chemosensory responses to brief exposures to hypoxia (100 percent N2; 5-s and 10-s) and hyperoxia (100 percent O2; 30-s), and intravenous injections of excitatory (NaCN 0.2-100 micrograms/kg) and inhibitory (dopamine hydrochloride 0.02-20 micrograms/kg) chemoreceptor agents. Hypoxia increased f chi, with a high temporal correlation between frequency levels in both nerves. Prolonging hypoxic stimulation increased {df chi/dt}d, with preservation of {df chi/dt}a. Hyperoxic exposure produced highly correlated decreases in f chi in both nerves, but reduced correlation in df chi/dt. Increasing doses of NaCN produced analogous increments in f chi, df chi/dt and their correlations, the {df chi/dt}a/{df chi/dt}d ratio remaining constant along all the experimental range, except in one animal in which the ratio increased in both nerves alike. Dopamine reduced f chi bilaterally, with chemosensory silencing being reached with doses of about 0.2-0.5 microgram/kg, the correlations between f chi's of both nerves remaining constant within the range analyzed. Maximal {df chi/dt}d was not affected along the range of dopamine doses, except in one animal in which it increased in both nerves. It is concluded that both carotid nerves convey similar quantitative information to the brain stem. Thus, the carotid nerves constitute either cooperative inputs or redundant afferences contributing to a high safety factor

Acetate enhances the chemosensory response to hypoxia in the cat carotid body in vitro in the absence of CO2-HCO3-

To determine if intracellular acidosis enhances hypoxic chemoreception in the absence of CO2-HCO3- at pH 7.4, the effects of sodium acetate (30 mM) were studied on the chemosensory responses of the cat carotid body to hypoxic, stagnant and cytotoxic hypoxia. Carotid bodies were perfused and superfused in vitro with Tyrode's solution, free of CO2-HCO3-, buffered with HEPES-NaOH, pH 7.40, at 36.5 +/d- 0.5 degrees C and equilibrated at PO2 of 125 Torr (perfusate) and < 20 Torr (superfusate). In the absence of acetate, hypoxia (PO2 25 Torr), flow interruption and NaCN (0.01-100 micrograms) augmented the chemosensory discharges. However, in the presence of acetate, the half-excitation time of these responses decreased and their amplitude increased. Thus, acetate enhances the chemosensory response to hypoxic, stagnant and cytotoxic hypoxia. It is suggested that that intracellular acidosis induced by acetate contributes to this potentiation by correcting the alkaline pHi caused by the absence of HCO3-(-)HCO2 in the perfusate

Phrenic nerve activity during artificial ventilation at different body temperatures and its relationships with carotid chemosensory activity

While the chemoreceptor discharges of carotid bodies in vitro are highly dependent on temperature, these chemoreceptors in situ contribute only moderately to the ventilatory adjustment to changing body temperature (Tb), probably because of the concomitant and reverse changes in natural chemoreceptor stimuli in closed-loop preparations. Accordingly, we studied the frequency of carotid chemosensory discharge (fx) and the phrenic integrated electroneurogram (IENGph) in pentobarbitone anesthetized cats, paralyzed with alcuronium and artificially ventilated, at three steady-state levels of Tb (35.5, 37.5 and 40.2 C) modifying the frequency and volume of ventilator to ontain...

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