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Biomedical subjects

Carlos Chan

Publications and source records attributed to Carlos Chan.

At least 19 recordsLinked to original sources
PubMed2006

Expression of steroidogenic factors 1 and 2 in normal human pancreas.

Orphan nuclear receptor steroidogenic factor-1 (SF-1) is crucial for development and function of steroidogenic organs. The steroidogenic factor-2 (SF-2) is an essential factor involved in cholesterol transfer and activation of promoters of steroidogenic enzymes CYP11A1, CYP17 and Steroidogenic Acute Regulatory Protein (StAR). We have previously demonstrated steroidogenic activity in pancreatic tissue. The aim of this study was to investigate the presence of SF-1 and SF-2 in human pancreas. Total RNA was extracted from normal male (five) and female (five) samples, obtained from the organs donor program. RT-PCR approach was used to analyze the expression of SF-1 and SF-2. Immunohistochemical analysis was performed for SF-1. The bands of expression were present in both male and female samples, although differential expression was observed. For both factors, the signal detected was more evident in males than in females. A similar pattern was present in the immunohistochemical study. Normal human pancreas expresses SF-1 and SF-2 factors similarly to ovary and adrenals. A distinctive characteristic is the sexually dimorphic expression of these factors. Our data provide evidence suggesting that the pancreas achieves steroidogenic activity supporting the presence of gender- and location-related differences in the expression of these steroidogenic factors.

Adrenal Glands↗
PubMed2006

Long-term evaluation of biliary reconstruction after partial resection of segments IV and V in iatrogenic injuries.

Roux-en-Y hepatojejunostomy is the procedure of choice for biliary reconstruction after complex iatrogenic injury that is usually associated with vascular injuries and concomitant ischemia of the ducts. To avoid the ischemic component, our group routinely performs a high repair to assure an anastomosis in noninflamed, nonscarred, and nonischemic ducts. If the duct bifurcation is preserved, the Hepp-Couinaud approach for reconstruction is an excellent choice. Partial liver resection of segments IV and V allows adequate exposure of the bile duct at its bifurcation with an anterior approach of the ducts (therefore not jeopardizing the circulation), allowing a high quality anastomosis. Long-term results of bile duct reconstruction using this approach are described. Two hundred eighty-five bile duct reconstructions were done between 1989 and 2004 in a tertiary care university hospital. The first partial-segment IV resection was done in 1994; 94 cases have been reconstructed since then using this approach. All of them had a complex injury (Strasberg E1-E5), and although in many cases the bifurcation was preserved (E1-E3), a high bilioenteric anastomosis was done to facilitate the reconstruction. In 70 cases, the bifurcation was identified, and in the 24 in which the confluence was not preserved, the right and left ducts were found except in one case. In three patients, the right duct was found unsuitable for anastomosis, and a liver resection was done. In the remaining 21, an anastomosis was done using a stent (transhepatic, transanastomotic) through the right duct. According to Lillemoe's criteria, 86 cases had good results (91%). In four of the eight remaining patients, there was the need to operate again due to the presence of an obstruction and/or cholangitis. In the rest, radiological instrumentation was done. Four of these cases have developed secondary biliary cirrhosis, two of which have died while waiting for a liver transplant, four and six years after reconstruction. Partial segments IV and V resection allows adequate exposure of the confluence and the isolated left or right hepatic ducts. Anterior exposure of the ducts allows an anastomosis in well-preserved, nonischemic, nonscarred, or noninflamed ducts. Parenchyma removal also allows the free placement of the jejunal limb, without external compression and tension, obtaining a high quality anastomosis with excellent long-term results.

Adolescent↗
PubMed2004

Central pancreatectomy as an indication for various benign pancreatic tumors.

Standard pancreatic resections, either proximal or distal ones, result in a considerable loss of pancreatic parenchyma and may cause impairment of the exocrine and endocrine functions. Central pancreatectomy has been indicated for small benign lesions located in the neck or body of the pancreas. It has the potential advantage of lowering the risk of functional impairment of the pancreatic parenchyma, biliary tract, upper gastrointestinal tract, and spleen. We present three cases of patients with benign, isolated pancreatic tumors who underwent a successful central pancreatectomy. From this small series, we believe that central pancreatectomy is an excellent therapeutic option for benign, localized pancreatic tumors.

Aged↗
PubMed2002

Application of molecular biology studies to gene therapy treatment strategies.

The diagnosis of pancreatic cancer continues to produce fear in both patients and practitioners in large part owing to the likely incurability in all for whom the diagnosis is made. It is this reality that continually motivates the surgical and medical oncologists who endeavor to treat these patients. Currently, the cure rate for pancreatic cancer has improved only minimally, and the overall survival of patients remains dismal, with fewer than 5% of patients alive at 5 years and 92% of these patients dead at 2 years. This current treatment status has stimulated numerous studies endeavoring to understand the diverse mechanisms of cell growth in this tumor. Intensive investigative efforts have produced the understanding of new tumor suppressor genes such as DPC4 and an increasing understanding of tyrosine kinase receptors and signal transduction and their regulation of programmed cell death (apoptosis). Detection of these numerous genetic defects may give new insights and understanding of the highly chemo- and radioresistant nature of pancreatic cancer. These same findings also provide the basis for the development of new potential therapies for pancreatic cancer through gene therapy. This paper reviews the significant molecular biologic findings and their influence on the development of gene therapy strategies in the treatment of pancreatic adenocarcinoma.

Adenocarcinoma↗
PubMed2002

To stent or not to stent bilioenteric anastomosis after iatrogenic injury: a dilemma not answered?

BACKGROUND: Bile duct injury is a complex and serious complication whose frequency has not diminished. A bilidigestive anastomosis (Roux-en-Y hepaticojejunostomy) is usually needed after complex injuries. Placement of an anastomotic stent is a matter of debate and to our knowledge there is no study that compares the results between stenting and not stenting the anastomosis. DESIGN: A retrospective review of medical records of patients operated on for biliary reconstruction after iatrogenic injury. SETTING: Tertiary care academic university hospital. PATIENTS: A comparative study was performed of patients operated on between 1995 and 1999, who were referred to our hospital for acute or elective reconstruction of the biliary tract following iatrogenic injury. All patients underwent Roux-en-Y hepaticojejunostomy. The patients were divided into 2 groups: those who underwent Roux-en-Y hepaticojejunostomy with a transanastomotic stent and those who underwent Roux-en-Y hepaticojejunostomy without a transanastomotic stent. MAIN OUTCOME MEASURES: Operative mortality, anastomotic dysfunction, biliary fistula, reoperations, postoperative complications, postoperative liver function tests. RESULTS: Sixty-three patients with high and complex biliary injuries (Bismuth type III, IV; Strasberg D, E). Thirty-seven cases had reconstruction with the placement of a transanastomotic stent and 26 did not have a stent placed. No operative mortality was observed. The postoperative outcomes of both groups were compared and no differences found. Good results were observed in more than 80% of the patients. Reoperations were more frequent in the nonstented group (15% vs. 5%) and complications were more frequent in the stented group (16% vs. 7%). CONCLUSIONS: Good results are obtained with a Roux-en-Y hepaticojejunostomy after complex injuries. The use of transanastomotic stents has to be selective according to the individual characteristics of each patient and the experience of each surgeon. We recommend their use when unhealthy (ie, ischemic, scarred) and small ducts (<4 mm) are found.

Anastomosis, Roux-en-Y↗
PubMedDate not supplied

Iatrogenic intestinal injury concomitant to iatrogenic bile duct injury: the second component.

OBJECTIVE: Bile duct injuries have a frequency of 0.1% to 0.3% even in the most experienced centers. Complex biliary lesions usually require a bilioenteric anastomosis, achieving good long-term results in 80% to 90% of the cases. Besides injuries to the abdominal contents during laparoscopy (by trocars or electrocautery), intestinal complications associated with reconstruction attempts can be observed. We analyzed the concomitant intestinal complications in 251 patients with iatrogenic biliary injuries reconstructed over this 12-year period. METHODS: A retrospective review of patients with biliary tract reconstruction after iatrogenic injury in a tertiary academic health-care center was done. All patients with concomitant intestinal injury were included; type of operation and postoperative outcome were analyzed. RESULTS: Among 251 patients, 35 cases had a concomitant intestinal injury. The most common site of fistulization was the duodenum (18 cases, 50%); 9 cases were associated with long-term subhepatic drains (more than three weeks), and the other 9 cases were associated with a dehiscent hepatoduodenostomy. Faulty Roux-en-Y reconstruction was observed in 5 cases. In 5 cases, fistulization of the jejunum and ileum, secondary to drain placement, was documented, as well as 3 cases with colonic injuries. Two patients had a dehisced Roux-en-Y anastomosis. One had a bilioenteric omega type ileal anastomosis, and 1 had a hepatoileal anastomosis without omega reconstruction. Primary repair of the duodenum with resection of the affected intestinal or colonic segment was done at the same time of biliary repair without related morbidity. CONCLUSIONS: Concomitant gastrointestinal injures were found with an incidence of 15% in our series. The most common site of fistulization is the duodenum. In half of the patients, it was secondary to a dehiscent hepatoduodenostomy, whereas in the other, it was caused by long-term subhepatic drains. Besides faulty Roux-en-Y reconstruction, fistulization was related with long-term drains. Primary repair and resection of the affected segment of jejunum, ileum, and colon can be done during the same operative stage of biliary reconstruction, without significant correlated mortality.

Academic Medical Centers↗
PubMedDate not supplied

Bile duct growing factor: an alternate technique for reconstruction of thin bile ducts after iatrogenic injury.

A variant of bilioenteric anastomosis, laterolateral hepatojejunostomy, is described in which the opened anterior aspect of the common hepatic duct and left hepatic duct is anastomosed to a Roux jejunal limb. This technique is specially designed for thin, injured bile ducts in which a conventional anastomosis is difficult due to the small diameter of the ducts. A wide anastomosis is obtained, leaving the posterior wall as a conduit for bile, ensuring an adequate anastomotic diameter.

Anastomosis, Surgical↗
PubMedDate not supplied

[Biliary stents for reconstruction in bile duct injuries. The role of bile acids].

UNLABELLED: Biliary stents, placed either surgically, endoscopically or radiologically are a frequent palliative and/or curative option for treatment of obstructive jaundice. Stones or sludge formation above or inside the stent are of major concern in that they cause dysfunction of the stent that needs prompt replacement. To evaluate the efficacy of ursodeoxycholic acid (UDCA) for long-term management of surgically placed biliary stents after iatrogenic injury, a prospective, controlled, randomized trial was conducted. METHOD: Patients with biliary tract reconstruction caused by iatrogenic injury that required a transanastomotic stent were randomized into a control group (N: 29) and into a UDCA (15 mg/kg day)-treated group (N: 30). Patients were followed on an external basis and a cholangiogram was obtained to verify stent patency. Liver function tests were also analyzed. RESULTS: The two groups were compared and no differences were observed. UDCA treated patients had significant elevation of transaminases and alkaline phosphatase. Two patients in the control group and four in the treated group developed lithiasis and/or sludge. CONCLUSION: No advantages were shown with administration of UDCA to maintain the biliary stents patent and to prevent neoformation of lithiasis and/or sludge. We conclude that no benefit is obtained with administration of UDCA to patients with biliary reconstruction and a transanastomotic stent.

Adult↗
PubMedDate not supplied

[Esophageal closed transection for surgical treatment of portal hypertension. A 10-year experience].

BACKGROUND: Extensive esophagogastric devascularization (Sugiura-Futagawa operation and complete portoazygos disconnection) are excellent alternate choices for low-risk patients (Child-Pugh A-B) in whom a selective shunt is not feasible, obtaining a low postoperative rebleeding rate and a good quality of life. Esophageal transection is an important step in these procedures because submucosal varices are obliterated, achieving complete portoazygos disconnection. Results during one decade with closed variant of esophageal transection are reported. METHOD: Between 1990 and 2000, 78 patients were operated on (69 Child-Pugh A and nine Child Pugh B) in two operative stages with Sugiura-Futagawa operation and complete portoazygos disconnection. Files of these patients were reviewed and recurrence of hemorrhage was evaluated as well as fistulization and dehiscence. RESULTS: Among 78 modified transections, only one case of dehiscence was observed (1.2%) (very early in our experience) with concomitant mortality. Rebleeding was observed in 11% of cases, with two cases of stenosis that required dilatation. During the last 7 years (57 patients), no complication has been observed. CONCLUSIONS: Modified transection has a very low complication rate with long-term results comparable to those of classic transection.

Digestive System Surgical Procedures↗
PubMedDate not supplied

[Iatrogenic injury of the bile duct. Experience with repair in 180 patients].

OBJECTIVE: Biliary duct lesions have a prevalence of 0.3-0.6% This prevalence is independent of the learning curve: The present paper evaluated survival and quality of life of patients following operative repair. METHODS: In a 12-year period, 180 patients underwent bile duct reconstruction. Of these patients (61 males and 129 females, mean age 39 years), 52% sustained injury during open operation and 42% during laparoscopic procedure. Quality of life was evaluated in the postoperative period. RESULTS: All 180 patients were treated surgically by means of Roux en Y hepaticojejunostomy. Transhepatic stents were used in 142 patients. Eight patients had independent left and right duct anastomosis and in 51 cases, partial resection of segment IV of liver to improve exposure of hilus was carried out. Mortality was 1.7%, due to multiorganic failure. After removal of stent, radiologic manipulation was required in 16% of cases to remove debris and stones or to dilate anastomosis. A total of 83% of patients were completely rehabilitated both clinically and biochemically. CONCLUSIONS: Bile duct injury has a good prognosis in specialized tertiary-care centers. Roux en Y hepatoyeyunostomy is procedure of choice with trans-hepatic stent when needed. Full rehabilitation can be achieved in 80% of patients.

Adult↗
PubMedDate not supplied

Liver transplantation for Wilson s disease: our experience with review of the literature.

BACKGROUND/AIMS: Orthotopic liver transplantation is being used with more frequency as the treatment for Wilson s disease. The experience at the Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran with orthotopic liver transplantation for Wilson s disease is reported. We perform an extensive literature review for this treatment modality. METHODS: Between january 2000 and june 2003, 23 orthotopic liver transplants were performed at our institution, 2 of them for Wilson s disease. Both the patients presented with chronic advanced liver disease and one presented neurologic dysfunction. RESULTS: Both the patients were transplanted without any major complication and are alive 43 and 22 months after the transplant respectively. To our knowledge 370 liver transplants have been reported in the international literature since 1994 for the treatment of Wilson s disease. CONCLUSIONS: Currently, orthotopic liver transplantation should be considered as a major option for the treatment of chronic liver disease in patients with Wilson s disease. Although it is well known that the transplant only partially corrects the defective metabolism in patients with Wilson s disease, it does convert the copper kinetics of a homozygous to that of a heterozigote, thus, providing an effective phenotypic cure.

Adolescent↗
PubMedDate not supplied

[Portal biliopathy].

Portal biliopathy is a rare condition that is usually not diagnosed. It is associated with presence of varix around bile duct with concomitant ischemic damage and structural alterations of bile duct wall; this produces obstructive phenomena. There are scarce reports on the literature this entity. In the present paper, we report two cases in which obstruction of extrahepatic bile duct was associated with cholecystitis with well-documented extrahepatic portal hypertension. Both cases were managed with cholecystectomy and endoscopic placement of endoprothesis. Treatment of portal biliopathy should be adjusted to the individual patient's characteristics. It is focused on the one hand on management of portal hypertension and on the other hand to management of obstructive jaundice. When cholecistitis is found, cholecistectomy should to be performed. If the patient develops concomitant gastrointestinal bleeding due to portal hypertension, management of the problem could require surgical devascularization, shunting procedures, or endoscopic variceal ligature.

Adult↗
PubMedDate not supplied

Current role of surgery for the treatment of portal hypertension.

Portal hypertension surgery has evolved widely in the last decades. Since the first surgical shunt was done in 1945 for the treatment of recurrent hemorrhage, many surgical options have been developed including selective shunts, low diameter shunts and extensive devascularization procedures. Many of them have been studied and compared showing their advantages and disadvantages, evolving also their role in the therapeutic armamentarium. Surgery is nowadays a second line treatment option (after b blockers and endoscopic therapy), and it's main indication is for patients whose main and only problem is history of bleeding, with good liver function (Child-Pugh A). For emergency situations it has a very limited role and for primary prophylaxis virtually has also no role. Patients with good liver function, electively operated with portal blood flow preserving procedures are the patients that benefit from surgical treatment. Patients with a bad liver function are better candidates for a liver transplant.

Esophageal and Gastric Varices↗
PubMedDate not supplied

Polysplenia syndrome in the adult patient. Case report with review of the literature.

AIMS: To report a case of polysplenia syndrome (PSS) in an adult patient. BACKGROUND: The PSS is a form of situs ambiguous with multiple spleen, cardiac anomalies, abdominal heterotaxia, short pancreas, major venous system and bronquial malformations. It is a rare syndrome, more often found in childhood, and only the 10% of the patients that do not have cardiac anomalies can reach adulthood. RESULTS: A 56 y/o male with obstructive jaundice and intestinal obstruction who was submitted to an abdominal laparotomy suspecting cholangiocarcinoma. He had choledocolithiasis, duodenal kinking by a preduodenal portal vein, intestinal levorotation, hypoplasic vena cava with a prominent acigos vein, short pancreas and polysplenia. A cholecistectomy, biliodigestive and gastroyeyunal bypasses were performed without any complications and with a successful evolution. CONCLUSIONS: In conclusion, PSS is a rare hereditary syndrome that often occurs in childhood and its discovery in an adult is frequently fortuitus. Surgical treatment is an excellent therapeutic option, however is reserved just for complications. The outcome is good and the final evolution depends on the degree of the cardiac anomalies.

Abnormalities, Multiple↗
PubMedDate not supplied

Surgical treatment of non-cirrhotic presinusoidal portal hypertension.

BACKGROUND/AIMS: Non-cirrhotic portal hypertension has a better prognosis than other forms of portal hypertension because of a well-preserved liver function in most cases. These patients are good candidates to receive surgical treatment, which is the therapeutic choice available with the lowest rebleeding rate. Because of abnormalities in the splanchnic vessels due to the nature of the diseases, many of them cannot be shunted. An extensive esophagogastric devascularization, the complete portoazygos disconnection, was evaluated. METHODOLOGY: A retrospective review of files of 31 patients, among 491 operations between 1991 an 2001 was carried out in a tertiary care Academic University Hospital. Patients comprised those with non-cirrhotic bleeding portal hypertension treated by means of complete portoazygos disconnection. Extensive two-stage (thoracic and abdominal) esophagogastric devascularization with modified transection of the esophagus was performed. MAIN OUTCOME MEASURES: recurrence of hemorrhage, encephalopathy and survival. RESULTS: Thirty-one patients were treated. In 17 cases (54%) a hypercoagulable state was demonstrated. No operative mortality was observed (0-30 days) with a total of 62 operations (two stages per patient). No case of encephalopathy was observed and in 3 cases (9%) rebleeding was recorded. The survival curve showed a 5-year survival of 97% and a 10-year survival of 93%. CONCLUSIONS: Complete portoazygos disconnection is an excellent surgical alternative for patients with non-cirrhotic portal hypertension, with a low morbidity and mortality as well as a low rebleeding rate and good long-term survival.

Adult↗
PubMedDate not supplied

Bile duct reconstruction after iatrogenic injury in the elderly.

UNLABELLED: Bile duct injuries occur with a frequency of 1 to 5 per 1000 cases as a result of an increase in the number of procedures performed. Elderly patients have more severe lithiasis- related diseases than the younger population. This fact increases the likelihood of conversion from laparoscopic to open surgery, and the probability of injury. We report the results of bile duct reconstruction after injury in these patients. SETTING: A tertiary care academic university hospital. METHODS: The files of patients over 65 years of age who had biliary tract reconstruction after iatrogenic injury were retrospectively reviewed. Post operative results, quality of life and failures from the repair were analyzed. RESULTS: 20 patients over the age of 65 were referred for biliary tract reconstructive surgery over a ten year period. Mean age was 71 (65 - 83). Nineteen cases were referred from other hospitals. Fourteen cases (60%) had comorbidities (type 2 diabetes mellitus, systemic hypertension). All patients were treated by means of Roux en Y hepatojejunostomy. No operative morbility was recorded and only one major complication (abdominal collection) was found. Two long term mortalities unrelated to surgery were found. Treatment success (as defined by the Johns Hopkins criteria) was obtained in 17 cases (85%) and only one patient (5%) required reoperation two years after the initial attempt. CONCLUSIONS: Elderly patients that survive biliary injury and are reconstructed have long-term results comparable to the younger population; Roux en Y hepatojejunostomy offers the best surgical choice.

Aged↗