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M A Mercado

Publications and source records attributed to M A Mercado.

At least 19 recordsLinked to original sources
PubMed2005

Evidence for Ca(2+)-permeable AMPA receptors in the olfactory bulb.

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (AMPARs), a subtype of glutamate receptor, contribute to olfactory processing in the olfactory bulb (OB). These ion channels consist of various combinations of the subunits GluR1-GluR4, which bestow certain properties. For example, AMPARs that lack GluR2 are highly permeable to Ca(2+) and generate inwardly rectifying currents. Because increased intracellular Ca(2+) could trigger a host of Ca(2+)-dependent odor-encoding processes, we used whole cell recording as well as histological and immunocytochemical (ICC) techniques to investigate whether AMPARs on rat OB neurons flux Ca(2+). Application of 1-naphthylacetyl spermine (NAS), a selective antagonist of Ca(2+)-permeable AMPARs (CP-AMPARs), inhibited AMPAR-mediated currents in subsets of interneurons and principal cells in cultures and slices. The addition of spermine to the electrode yielded inwardly rectifying current-voltage plots in some cells. In OB slices, olfactory nerve stimulation elicited excitatory responses in juxtaglomerular and mitral cells. Bath application of NAS with d,l-2-amino-5-phosphonovaleric acid (AP5) to isolate AMPARs suppressed the amplitudes of these synaptic responses compared with responses obtained using AP5 alone. Co(2+) staining, which involves the kainate-stimulated influx of Co(2+) through CP-AMPARs, produced diverse patterns of labeling in cultures and slices as did ICC techniques used with a GluR2-selective antibody. These results suggest that subsets of OB neurons express CP-AMPARs, including functional CP-AMPARs at synapses. Ca(2+) entry into cells via these receptors could influence odor encoding by modulating K(+) channels, N-methyl-d-aspartate receptors, and Ca(2+)-binding proteins, or it could facilitate synaptic vesicle fusion.

Animals↗
PubMed2003

Acute bile duct injury. The need for a high repair.

BACKGROUND: An immediate repair is considered optimal in acute biliary duct injuries; however, it may prove to be a challenge, because such repairs are usually performed on small ducts whose viability cannot always be determined. METHODS: We performed a retrospective review of the charts of patients with acute bile duct injury who underwent repair at a tertiary care academic university hospital. A total of 204 patients with acute bile duct injury were seen between 1989 and 2002. Of these, 30 were repaired within minutes to hours after the injury. These patients were divided into two groups. Group I patients had a Roux-en-Y hepatojejunostomy below the hepatic junction; Group II patients had a Roux-en-Y hepatojejunostomy at the junction level. We then performed a long-term evaluation of anastomosis function in these patients, using clinical, radiological, and laboratory. RESULTS: Twenty-eight injuries were secondary to a laparoscopy; the other two resulted from open cholecystectomies. All of the patients suffered complex injuries with complete section of the duct and substance loss (Strasberg E). There were 12 patients in group I and 18 in group II. Three cases in group I (25%) and one in group II (5%) developed anastomosis dysfunction. Mean follow-up was 56 months (range, 12-80) in group I and 52 months (range, 10-76) in group II. Two cases in group I (16%) and none in group II (0) required reoperation (p < 0.05). CONCLUSIONS: In the acute setting, complex lesions should be treated with a high bilioenteric anastomosis (at the junction level) in the first attempt at repair. Lower-level anastomoses are associated with a higher dysfunction rate and the need for radiological manipulation and reoperation. Also, stenosis of the anastomosis secondary to undetected duct ischemia in the acute repair is more frequent in low bilioenteric anastomoses.

Acute Disease↗
PubMed2000

The evolution of portal hypertension surgery: lessons from 1000 operations and 50 Years' experience.

HYPOTHESIS: Surgery for portal hypertension has evolved widely in the past decades. Selection criteria and the type of operations have evolved because of the appearance of other therapeutic alternatives, such as pharmacotherapy, endoscopic therapy, transjugular intrahepatic portosystemic shunt, and liver transplantation. We believe the surgical approach has a therapeutic role in a select patient population. DESIGN: Retrospective review of the medical records of patients operated on for bleeding portal hypertension in the past 50 years. SETTING: An academic tertiary care university hospital. PATIENTS AND METHODS: In a 50-year period, 1000 operations for the treatment of bleeding portal hypertension have been done, including shunts and devascularization procedures. In the past years, in low-risk (Child-Pugh classification A) selected patients, only portal blood flow-preserving operations have been done. RESULTS: Non-portal blood flow-preserving procedures had a wide spectrum of results, with a high encephalopathy rate and short long-term survival. The results with portal blood flow-preserving procedures in the past 10 years are as follows: operative mortality, 2.7%; postoperative encephalopathy, 6%; rebleeding, 6%; and shunt obstruction, 4%. CONCLUSIONS: Portal hypertension surgery has a role in elective operations and in low-risk selected patients, when portal blood flow-preserving procedures are done. The type of operation is selected according to the individual characteristics of each patient.

Gastrointestinal Hemorrhage↗
PubMed2000

Surgery in Mexico.

Explore the source record for details and available documents.

General Surgery↗
PubMed2000

A comparative study of the elective treatment of variceal hemorrhage with beta-blockers, transendoscopic sclerotherapy, and surgery: a prospective, controlled, and randomized trial during 10 years.

OBJECTIVE: To compare three options for the elective treatment of portal hypertension during a 10-year period. METHODS: Patients included in the trial were 18 to 76 years old, had a history of bleeding portal hypertension, and had undergone no prior treatment. Treatment options were beta-blockers (propranolol), sclerotherapy, and portal blood flow-preserving procedures (selective shunts and the Sugiura-Futagawa operation). RESULTS: A total of 119 patients were included: 40 in the pharmacology group, 46 in the sclerotherapy group,and 33 in the surgical group. The three groups showed no differences in terms of age, Child-Pugh classification, and cause of liver disease. The rebleeding rate was significantly lower in the surgical group than in the other two groups. The rebleeding rate was only 5% in the Child A surgical group, compared with 71% and 68% for the sclerotherapy and pharmacotherapy groups, respectively. Survival was better for the low-risk patients (Child A) in the three groups, but when the three options were compared, no significant difference was found. CONCLUSIONS: Portal blood flow-preserving procedures offer the lowest rebleeding rate in low-risk patients undergoing elective surgery.

Adolescent↗
PubMed1999

Biliary duct injury: partial segment IV resection for intrahepatic reconstruction of biliary lesions.

A technique for intrahepatic reconstruction of the biliary tree after complex high injuries is described. The fundament of the procedure is the removal of a wedge of segment IV at the level of the hilar plate. When the hilar plate is reached and no adequate exposure of the ducts can be obtained, removing a 1 x 1-in wedge of segment IV between the gallbladder bed and the round ligament exposes the left and right ducts. An anteroposterior view of the plate is obtained instead of a caudocephalic dissection, exposing healthy, nonscarred ducts for reconstruction. We have used this approach in 22 patients, and adequate exposure of the ducts has been obtained, with a high success rate of patency of the anastomosis at a mean follow-up of 3 years. Twenty patients have a patent anastomosis, with a good quality of life and no restenosis.

Adult↗
PubMed1999

Results of surgical treatment (modified Sugiura-Futagawa operation) of portal hypertension associated to complete splenomesoportal thrombosis and cirrhosis.

BACKGROUND: Hemorrhagic portal hypertension, secondary to both intrahepatic and extrahepatic portal hypertension, is an uncommon entity. In this condition, the extrahepatic and the intrahepatic obstruction of the portal vein, due to chronic liver disease, produce a more severe form of hemorrhagic portal hypertension that is more difficult to control. The results of surgical treatment (modified Sugiura-Futagawa operation) in this subset of patients is analyzed. METHODS: Among 714 patients with a history of hemorrhagic portal hypertension, 14 cases were found with histologically proven liver cirrhosis and complete splenomesoportal thrombosis demonstrated by means of preoperative angiography. Patients with incomplete (partial) splenomesoportal thrombosis were excluded. There were nine males and 5 females with a mean age of 51 years. Alcoholic cirrhosis was demonstrated in 50% of the cases, post hepatitic cirrhosis in 28%, primary biliary cirrhosis in 7%, and cryptogenic cirrhosis in 14%. There were nine Child-Pugh A and 5 B cases. All cases were treated by means of our modified Sugiura-Futagawa procedure. RESULTS: Bleeding recurrence from esophagogastric varices was shown in one case, colonic varices in one case and hypertensive gastropathy in another of the survivors. Post operative encephalopathy was shown in 3 of the cases. The thirty-six month survival rate was 30% (Kaplan-Meier). CONCLUSIONS: The combination of intrahepatic plus extrahepatic portal hypertension has a worse prognosis. Treatment options are limited (sclerotherapy and/or devascularization), because shunt surgery, TIPS and liver transplantation have a very restricted role and postoperative outcome is poor.

Adolescent↗
PubMed1999

Reoperations for bleeding portal hypertension. Surgical rescue of surgical failures.

BACKGROUND: Surgery for portal hypertension has a low rebleeding rate. Patients that rebleed can be grossly divided into those who die as a consequence of the episode, those who don't die but develop liver failure (remaining as Child-Pugh C) and those who, in spite of the bleeding episode, retain good liver function (Child-Pugh A or B). At our hospital, the latter group is considered for further surgical treatment. We report here the results of surgical rescue of surgical failures. METHODS: In a twenty year period, 36 patients (30 Child-Pugh A, 6 Child-Pugh B) were reoperated. The files of these patients were reviewed. RESULTS: Average age was 33 years. Cirrhosis was present in 31 cases. All patients were electively reoperated with portal blood flow preserving procedures. Operative mortality for the whole group was 12% and for the Child-Pugh A group 6.6%. Rebleeding was observed in 5.5%. Postoperative incapacitating encephalopathy was recorded in one case (2.7%). Good quality of life was recorded in 84% of the cases. Survival (Kaplan-Meier) was 78% at 6 months and 69% at 5 years. CONCLUSIONS: Surgical failures in low risk patients (Child-Pugh A or B) can be treated by means of surgery, and a low mortality, re-bleeding and encephalopathy rate can be expected. The performance of a portal blood flow preserving procedure is recommended.

Adolescent↗
PubMed1998

Is splenectomy necessary in devascularization procedures for treatment of bleeding portal hypertension?

OBJECTIVE: To investigate whether splenectomy as a part of devascularization procedures is necessary. DESIGN: Prospective, controlled, randomized trial. SETTING: University hospital, referral center. PATIENTS: A total of 55 patients (Child-Pugh class A and B) with a history of bleeding portal hypertension were treated by means of a modified Sugiura-Futagawa procedure. Twenty-three patients underwent splenectomy and 22 did not. METHODS: Postoperative outcome was recorded and comparison of the 2 groups was done with the Fisher exact test. Kaplan-Meier survival curves were constructed. Main outcome and postoperative differences between the patients who underwent splenectomy and those who did not were investigated. RESULTS: Both groups were comparable in the postoperative period. Significant differences were observed in transfusion requirements and postoperative portal vein thrombosis, both favoring the group without splenectomy. No differences in rebleeding, encephalopathy rate, operative time, or postoperative complications were observed. CONCLUSION: Splenectomy is not routinely necessary in devascularization procedures for bleeding portal hypertension.

Adolescent↗
PubMed1998

Comparative study of 2 variants of a modified esophageal transection in the Sugiura-Futagawa operation.

OBJECTIVE: To compare 2 techniques of esophageal transection in our modification of the Sugiura-Futagawa procedure for the treatment of bleeding portal hypertension in low-risk patients who cannot undergo surgery to have shunts placed. DESIGN: A prospective controlled trial comparing 2 variants of transection (classic, complete section of the anterior muscularis externa and whole mucosa; modified, placement of a circumferential running suture without opening the mucosa). SETTING: Academic university hospital. PATIENTS: Eighty-three low-risk patients (Child-Pugh score A and B) with a history of bleeding portal hypertension were operated on (35 classic, 48 modified transections) between 1989 and 1996. Both groups were comparable. MAIN OUTCOME MEASURES: Postoperative dehiscence of the transection was evaluated as well as fistulization, postoperative stenosis, rebleeding, postoperative endoscopic findings, survival, and mortality. RESULTS: Fistulization was observed in 1 (2%) of the patients in the modified group, and dehiscence in 1 patient (2%). In the classic group, 3 (8%) of the patients had dehiscence (relative risk, 2.6) and 1 (2%) of the patients, fistulization. No differences were observed regarding rebleeding (6 patients [6%] vs 5 patients [7%]), postoperative stenosis (4 patients [8%] vs 5 patients [10%]), postoperative endoscopic findings, survival, and mortality (early and late). CONCLUSION: The modified variant of the transection has a lower frequency of postoperative dehiscence, with the same long-term results.

Esophageal and Gastric Varices↗
PubMed1998

Analysis of factors affecting outcome after hepatectomy of patients with liver cirrhosis and small hepatocellular carcinoma.

OBJECTIVE: To review our policy of screening patients at risk of developing hepatocellular carcinoma (HCC), and to present 10 years' experience of hepatic resection for small HCC (< 5 cm). DESIGN: Retrospective study. SETTING: Teaching hospital, Germany. SUBJECTS: 861 patients with hepatic cirrhosis and oesophageal varices of whom 151 (18%) had HCC confirmed histologically; 30 of these tumours (20%) were less than 5 cm in diameter and suitable for resection. INTERVENTIONS: Segmentectomy (n = 14) bisegmentectomy (n = 10), and oncologically defined wedge resection (n = 6). MAIN OUTCOME MEASURES: Mortality, morbidity, and survival. RESULTS: 4 patients died within 30 days of liver failure and sepsis (n = 20, liver failure (n = 1), and bronchopneumonia (n = 1). The main beneficial prognostic factors were Child classification, donation of autologous blood, and an encapsulated tumour. The main indicators of a poor prognosis were invasion of the liver, venous invasion, invasion of the resection margin, and the presence of microsatellite tumours and nodules. 12 of the 26 survivors developed recurrences during the first five years postoperatively (46%). Kaplan-Meier survival curves showed that survival at 1 year was 80%, at 3 years 65%, and 5 years 50%, and at 10 years 30%. CONCLUSION: Hepatic resection is a useful treatment for small HCC, but its success depends on early detection and careful selection of patients.

Aged↗
PubMed1997

Surgery in elderly patients in Mexico. Portal hypertension surgery as an example.

Although people older than 65 years represent less than 5% of Mexico's registered population, medical care for elderly patients requires a multidisciplinary approach. In our academic university hospital, they are managed by a team of specialists. As an example of this approach, we evaluated the surgical treatment of bleeding portal hypertension in a highly selected elderly population. A retrospective study was done reviewing the files of 25 patients older than 65 years. All had good liver function (Child-Pugh class A and B) and had undergone elective surgery. Sixteen of them were women. The mean age was 68.8 years (age range, 65-76 years), and most had a diagnosis of cirrhosis. All patients were treated with portal blood flow-preserving procedures (selective shunts or Sugiura-Futagawa procedures). The operative mortality was 8%. Eight later deaths were recorded, with a mean follow-up of 25 months (range, 2-110 months). Survival (Kaplan-Meier) was 87% at 12 months, 54% at 60 months, and 45% at 110 months. Two rebleeding incidents were recorded as well as 3 cases of postoperative encephalopathy. We concluded that well-selected elderly patients, undergoing elective surgery with portal blood flow-preserving procedures, have a good postoperative outcome.

Age Factors↗
PubMed1997

Selective shunts for portal hypertension: current role of a 21-year experience.

The results of treatment of hemorrhagic portal hypertension with selective shunts over a 21-year period in a selected patient population are reported. Patients selected for surgical treatment had good cardiopulmonary and renal function, and most also had adequate liver function (141 Child-Pugh class A, 59 class B). Among 734 patients treated surgically for bleeding portal hypertension, 221 had selective shunts (168 distal splenorenal and 53 splenocaval shunts). Global operative mortality (in the 21-year period) was 14% and 12% for Child-Pugh A patients. Operative mortality in Child-Pugh A patients in the last 5 years was only 5%. The rate of rebleeding was 6%, rate of incapacitating encephalopathy was 5%, and rate of survival was 65% at 15 years (last 5 years: 88% at 1 year and 85% at 5 years). Good quality of life was demonstrated in 80% of surviving patients. Shunt patency was 94%. Postoperative portal blood flow changes occurred in 23% of cases (8% diameter reduction, 14% thrombosis). Compared with other forms of therapy (pharmacotherapy, sclerotherapy, and transjugular intrahepatic shunting), only liver transplantation offers similar results for these patients. In countries in which liver transplantation is not routinely performed, shunting with selective shunts is the treatment of choice for patients with good liver function.

Angiography↗
PubMed1996

Distal splenorenal shunt versus 10-mm low-diameter mesocaval shunt for variceal hemorrhage.

BACKGROUND: Portal hypertension surgery remains a good therapeutic choice for well selected patients with variceal bleeding. The distal splenorenal shunt (DSRS) has shown good long-term results and low-diameter shunts have emerged as an alternate choice. METHODS: A prospective, controlled and not randomized study was designed to compare the DSRS (23 patients) and the low-diameter 10 mm ring reinforced PTFE mesocaval shunt (LDMCS) (22 patients) in low-risk electively operated patients (Child-Pugh A-B). The operation was selected according to the anatomical status of the veins. RESULTS: Both groups were comparable. No differences were observed regarding rebleeding, operative mortality and survival. Significative differences were observed regarding encephalopathy and shunt thrombosis (higher in the LDMCS). Postoperative angiography showed better maintenance of portal blood flow in the DSRS group. CONCLUSIONS: Both operations are adequate alternatives for the elective treatment of portal hypertension in low-risk patients. However, the DSRS has more advantages than the LDMCS.

Adult↗
PubMed1996

Cytokine gene expression in cirrhotic and non-cirrhotic human liver.

BACKGROUND/AIMS: In order to explore the role of cytokines in the pathogenesis of liver cirrhosis, we analyzed their gene expression in hepatic biopsies from patients with alcoholic liver cirrhosis, post-hepatitis C liver cirrhosis, and with idiopathic portal hypertension without cirrhosis. METHODS: We assessed the gene expression of interleukins 1 beta, 2, 6, 8, and 10, as well as of tumor necrosis factor-alpha, transforming growth factor-beta and interferon-gamma by a quantitative polymerase chain reaction. RESULTS: We found high levels of transforming growth factor-beta in post-hepatitis C liver cirrhosis, high to moderate in alcoholic liver cirrhosis and low in non-cirrhotic specimens. Expression of interleukin-10, tumor necrosis factor-alpha, and interferon-gamma genes was detected in most post-hepatitis C liver cirrhosis, but not in idiopathic portal hypertension or alcoholic liver cirrhosis biopsies. The interleukin1-beta, 6 and 8 gene expression was significantly lower in alcoholic liver cirrhosis compared to post-hepatitis C liver cirrhosis, but higher compared to idiopathic portal hypertension specimens. Thus, post-hepatitis C liver cirrhosis samples showed a high degree of cytokine gene expression, whereas in alcoholic liver cirrhosis it tended to be moderate, and restricted to some cytokines (transforming growth factor-beta, interleukin-1, 6 and 8, but not interleukin-10, tumor necrosis factor-alpha or interferon-gamma). In contrast, most non-cirrhotic specimens showed a restricted and low cytokine gene expression. CONCLUSIONS: These data suggest that transforming growth factor-beta may have an important role in liver fibrosis and inflammation. Interleukin-1 beta, 6, 8, tumor necrosis factor-alpha and interferon-gamma, appear to participate in the pathogenesis of the mild to severe inflammatory phenomena seen in alcoholic and post-hepatitis C liver cirrhosis, respectively. Our data suggest that tumor necrosis factor-alpha does not participate in the hepatocellular damage of alcoholic liver cirrhosis, and indicate that neither interferon-gamma nor interleukin-10, at least at the levels observed in post-hepatitis C liver cirrhosis, are able to counteract the fibrotic/inflammatory process seen in this condition.

Adolescent↗
PubMed1995

Comparison of outcomes and complications for open and laparoscopic cholecystectomy in Mexico.

A retrospective analysis of the outcome and surgical complications of two groups of patients undergoing cholecystectomy was performed. Group I consisted of 253 patients who underwent laparoscopic cholecystectomy between 1991 and 1994, and group II was formed by 292 patients who met the same preoperative criteria than patients of group I and underwent open cholecystectomy between 1986 and 1990, prior to the introduction of laparoscopic cholecystectomy in our hospital. General characteristics and associated clinical conditions were similar for both groups. Intraoperative cholangiography was used more frequently in group II whereas preoperative ERCP was performed more frequently in group I patients. There was no operative mortality in any of the groups. There were no statistically significant differences between both groups in terms of type and number of complications.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1995

Angiographic evaluation after portal blood flow preserving operations.

We carried out a prospective study comparing postoperative portal angiographic characteristics in patients with hemorrhagic portal hypertension treated electively by two different portal blood flow preserving procedures. Between 1986 and 1991, a total of 81 patients underwent operation: 38 selective shunts and 43 Sugiura-Futagawa procedures. Cirrhosis was shown by biopsy in 50 cases, 26 of them secondary to alcoholism. We found rebleeding in 5% of the patients, incapacitating postoperative encephalopathy in 8%, and an operative mortality of 7%. Fifty-two cases were evaluated in the postoperative period with angiography; 21 patients treated with a Sugiura-Futagawa operation were excluded due to portal vein thrombosis shown in the preoperative studies. Postoperative portal vein thrombosis was found in 11 cases (21%) [seven cases in the Warren group (21%) and four cases in the Sugiura-Futagawa group (20%)]. Decreased portal vein diameter was seen in eight cases (15%). The two procedures maintained hepatopedal portal blood flow, and no change was seen in relation to the preoperative state in 66% of the operated patients. We found no significant differences between the two procedures. Selection of procedure depends on the individual characteristics of each patient.

Adult↗