Novel strategy for a bispecific antibody: induction of dual target internalization and degradation

Activation of the extensive cross-talk among the receptor tyrosine kinases (RTKs), particularly ErbB family-Met cross-talk, has emerged as a likely source of drug resistance. Notwithstanding brilliant successes were attained while using small-molecule inhibitors or antibody therapeutics against specific RTKs in multiple cancers over recent decades, a high recurrence rate remains unsolved in patients treated with these targeted inhibitors. It is well aligned with multifaceted properties of cancer and cross-talk and convergence of signaling pathways of RTKs. Thereby many therapeutic interventions have been actively developed to overcome inherent or acquired resistance. To date, no bispecific antibody (BsAb) showed complete depletion of dual RTKs from the plasma membrane and efficient dual degradation. In this manuscript, we report the first findings of a target-specific dual internalization and degradation of membrane RTKs induced by designed BsAbs based on the internalizing monoclonal antibodies and the therapeutic values of these BsAbs. Leveraging the anti-Met mAb able to internalize and degrade by a unique mechanism, we generated the BsAbs for Met/epidermal growth factor receptor (EGFR) and Met/HER2 to induce an efficient EGFR or HER2 internalization and degradation in the presence of Met that is frequently overexpressed in the invasive tumors and involved in the resistance against EGFR- or HER2-targeted therapies. We found that Met/EGFR BsAb ME22S induces dissociation of the Met-EGFR complex from Hsp90, followed by significant degradation of Met and EGFR. By employing patient-derived tumor models we demonstrate therapeutic potential of the BsAb-mediated dual degradation in various cancers.

Randomized, phase I, and pharmacokinetic (PK) study of RAD001, an mTOR inhibitor, in patients (pts) with advanced hepatocellular carcinoma (HCC)

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Background: RAD001, an orally administered, novel mTOR inhibitor has recently been extensively evaluated in cancer therapy. Up-regulation of mTOR expression has been noted in 40–45% of HCC, and preclinical studies suggest mTOR inhibitor can effectively inhibit proliferation of HCC cells as well as growth of HCC xenograft in mice. In addition, cytochrome P450 system is known to involve in metabolism of rapamycin analogues, and elimination of RAD001 is impaired in pts with hepatic dysfunction. The study aims to define the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and PK of daily- and weekly-dosing RAD001 in advanced HCC pts. Methods: Advanced HCC pts who were not feasible for or progressed after local therapy (surgery, percutaneous ablation or transcatheter arterial chemoembolization), ECOG PS 0–2, Child-Pugh's score < 8, and adequate hepatic, renal and hematological functions were eligible. The doses of RAD001 for daily-dosing arm would be escalated from 2.5, 5.0, 7.5 to 10.0 mg, and from 20, 30, 50 to 70 mg in weekly-dosing arm. Four weeks of treatment was regarded as one cycle. PK samples were collected on days 1 of cycle 1 and 2. Results: A total of 36 pts (M/F 34/2; median age 58.5, range 28–75; Child-Pugh's class of A/B 31/5) were enrolled. Number of pts with DLT/enrollment for dose level I, II, III and IV in daily arm was 1/6 (grade 3 hyperbilirubinemia), 1/6 (grade 4 thrombocytopenia), 0/3 and 2/3 (grade 3 diarrhea and rectal bleeding in 1 and grade 3 diarrhea and cardiac ischemia in 1), respectively; whiles in weekly arm was 0/3, 1/6 (grade 3 ALT elevation), 0/3 and 1/6 (grade 3 infection), respectively. MTD for weekly- and daily- dosing schedule was 70 mg and <7.5 mg, respectively. Reactivation of HBV and HCV was observed in 4 and 1 pts, respectively. The disease control response (DCR) of 31 evaluable pts was 61% (10/16) and 46.7% (7/15, including one PR) of pts receiving daily and weekly treatment, respectively. However, the DCR for weekly-dosing pts received >50 mg was 75% (4/6). Conclusions: Patient accrual is ongoing to complete. However, preliminary data suggest RAD001 is moderately active in stabilizing the progression of HCC, and PK data will be important to determine the optimal dosing schedule of RAD001 for HCC pts.

[Table: see text]

Infrared thermography to mass-screen suspected SARS patients with fever

Fever greater than 38 degrees C is a cardinal sign of patients with the severe acute respiratory syndromes (SARS). To reduce the risk of nosocomial cross infections, screening all patients and visitors who visit hospitals and clinics for fever at the entrance of every hospital building has become a standard protocol in Taiwan during the SARS epidemic from mid-April to mid-June 2003. We used a digital infrared thermal imaging (DITI) system (Telesis Spectrum 9000 MB) to conduct mass screening of patients and visitors who entered the hospital to identify those with fever. The DITI system has two components: a sensor head and a PC imaging workstation. The sensor head is an optic-mechanical device which consists of imagining optics for focusing the infrared source information on the infrared detector. The infrared images are further converted into electrical signals, which are then processed for real-time display on the monitor. During the period from April 13 to May 12 2003, 72,327 outpatients and visitors entered Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan. A total of 305 febrile patients (0.42%) was detected by infrared thermography. Among them, three probable SARS patients were identified after thorough studies including contact history, laboratory tests and radiology examinations. The findings suggests that infrared thermography was an effective and reliable tool ideal for mass-screening patients with fever in the initial phase of screening for SARS patients at a busy hospital which sees approximately 3,000 outpatients every weekday during the SARS epidemic.

Clinicopathologic correlation of serum tissue polypeptide specific antigen in hepatocellular carcinoma

OBJECTIVE

Recently, tissue polypeptide specific antigen (TPS) has been introduced as a cell proliferation marker. Little is known about its clinical significance in hepatocellular carcinoma (HCC). This study aimed to clarify serum TPS levels and tumor invasiveness of HCC.

METHODS

Serum TPS levels were determined with a monoclonal TPS IRMA assay in 69 patients with HCC. A correlation between serum TPS levels and clinical, biochemical, and pathological features was sought and compared with that of alpha-fetoprotein (AFP). In 57 healthy subjects, 56 patients with biopsy-proven chronic hepatitis and in 49 patients with liver cirrhosis, serum TPS levels were assayed and compared.

RESULTS

Serum TPS levels were significantly correlated with glutamic oxalacetic transaminase (p < 0.0001), glutamic pyruvic transaminase (p < 0.001), and lactate dehydrogenase (p = 0.027). There tended to be a positive relationship between serum TPS levels and tumor size, histological differentiation, capsular invasion, portal invasion, and clinical staging, although it did not reach statistical significance. A significant correlation, however, was observed between AFP and tumor size (p = 0.01), number (p = 0.042), histological grading (p = 0.028), portal invasion (p = 0.009), and clinical staging (p = 0.03). Patients with HCC had significantly higher TPS than healthy subjects (p < 0.001). However, there was substantial overlap between patients with HCC, chronic hepatitis, and liver cirrhosis.

CONCLUSIONS

Our data suggest that serum TPS is not significantly related to tumor invasiveness in patients with HCC. Serum TPS levels are affected by the proliferative activity of the underlying chronic liver disease, which is frequently associated with HCC in Chinese patients. As a cell proliferation marker, serum TPS should be interpreted cautiously in the presence of chronic liver disease.

Hepatofugal flow on computed tomography of arterial portography: its correlation with esophageal varices bleeding

BACKGROUND/AIMS

To study the portal flow patterns from CTAP (computed tomography of arterial portography), then to predict the existence of esophageal varices bleeding clinically.

METHODOLOGY

192 patients who underwent CTAP from superior mesenteric artery infusion were recruited in this study. The obtained images were classified according to our proposed criteria. Stage 0: hepatopetal flow, when all the contrast medium from the superior mesenteric vein entered the portal vein. Stage 1: when the contrast medium opacified the splenic vein or the other collateral vessels. Stage II: when the contrast medium opacified the paraesophageal vessels without entering the inner wall of the esophagus. Stage III: when the contrast medium opacified the collaterals up to the inner wall of the esophagus.

RESULTS

The incidence of bleeding esophageal varices was correlated to the different stages of collateral flows pattern obtained. The esophageal varices bleeding rates were 0/137, 1/16, 1/14, 16/25 for stage 0, I, II and III, respectively. The incidence of bleeding esophageal varices was significantly higher in stage III group than in the other groups (P < 0.001). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of stage III patients in regard to the occurrence of bleeding esophageal varices were estimated as 80.0%, 98.8%, 88.9%, 94.8%, and 94.3%, respectively.

CONCLUSIONS

Our results show that CTAP demonstrates the portal flow patterns and collateral veins clearly, which can serve as an excellent imaging modality to predict the risk of esophageal varices bleeding.

Carbon urea breath test is not as accurate as endoscopy to detect Helicobacter pylori after gastrectomy

BACKGROUND

This study was conducted to determine (1) whether Helicobacter pylori infection decreases in conjunction with time elapsed after gastrectomy and (2) the diagnostic efficacy of (13)C urea breath test (UBT) for H pylori in patients after gastrectomy.

METHODS

From January 1997 to June 1998, 86 patients who had undergone gastrectomy and 180 patients with dyspepsia without gastrectomy were enrolled. A UBT for the analysis of excess (13)CO(2)/(12)CO(2) ratio (ECR) was obtained for each patient. Each patient also underwent endoscopy to obtain gastric biopsies for histology and H pylori culture. The presence of H pylori by either histology or culture served as the standard to test the efficacy of UBT. The 86 patients with a prior gastrectomy were categorized into 3 subgroups (I, less than 1 year; II, 1 to 3 years; III, greater than 3 years), according to the interval between surgery and UBT. The initial H pylori status of these 86 patients was determined by histologic evaluation of the resected stomach.

RESULTS

At trial initiation, the postgastrectomy group had a lower H pylori infection rate (52.3%) as compared with the dyspeptic control group (80%). The initial H pylori status among subgroups I, II, and III was similar. There was a trend for the presence of H pylori in the stomach to decrease with increasing time elapsed after surgery (I to III: 68.8%, 48.3%, 36%, respectively; p < 0.05). The maximum UBT sensitivity and specificity achieved were 82.2% and 87.8% in the gastrectomy group and 97.2% and 96.3% in the dyspeptic group, with cutoff points of 2.5 and 4.0, respectively.

CONCLUSION

The prevalence of H pylori diminishes with time elapsed after gastrectomy. UBT for detection of H pylori is more effective in patients without prior gastrectomy than in patients who have undergone gastrectomy and is less effective than endoscopy for patients who have had a gastrectomy.

Incisional hernia after laparotomy: prospective randomized comparison between early-absorbable and late-absorbable suture materials

Incisional hernia is a serious postoperative complication of laparotomy. Selecting an appropriate suture material may lessen such morbidity. This study undertook a prospective, randomized comparison of early-absorbable polyglactin 910 suture versus late-absorbable polydioxanone loop suture for fascial closure after abdominal surgery. A series of 340 consecutive patients undergoing elective laparotomy were randomized to have fascial closure with either polyglactin 910 suture or polydioxanone loop suture between October 1993 and August 1996. A 2-year follow-up revealed that 23 patients had died, and the overall mortality rate was 6.8% (23/340). Ten (10/340, 2.9%) patients, including seven with polyglactin 910 suture and three with polydioxanone loop suture, developed incisional hernias. The early postoperative evaluation revealed an incidence of wound infection of 4.1% (14/340). The development of incisional hernia was not secondary to postoperative wound infection in this study. Among these 340 patients, 192 had malignant diseases and 148 had nonmalignant ones. Fascial closure with polyglactin 910 suture was associated with more incisional hernias than that with polydioxanone loop suture, with marginal significance for patients in the malignant group (4.7% versus 0%, p = 0.07) but not in the nonmalignant group (2.6% versus 4.2%, p = 0.67). In conclusion, abdominal closure with a late-absorbable polydioxanone loop suture may be beneficial to patients with a malignant disease for preventing incisional hernia.

Identification of a pre-S2 mutant in hepatocytes expressing a novel marginal pattern of surface antigen in advanced diseases of chronic hepatitis B virus infection

BACKGROUND AND AIMS

The expression of hepatitis B viral (HBV) antigens in liver tissue reflects the replicative status of chronic HBV infection. We have previously recognized a novel marginal pattern of hepatitis B surface antigen (HBsAg) in hepatocytes, which usually clusters in groups and emerges at the late non-replicative phase. This study was designed to investigate whether the marginal-type HBsAg represented the gene product of a specific HBV-surface mutant.

METHODS

Microdissection of cirrhotic nodules homogeneously expressing marginal HBsAg was performed on two of 12 resected livers from HBsAg-seropositive patients with hepatocellular carcinoma. The gene presumably encoding marginal HBsAg was polymerase chain reaction (PCR)-cloned, sequenced and analysed. In vitro transfection and expression of the cloned surface mutant plasmids were performed on the Huh7 cell line to illustrate intrahepatic HBsAg expression.

RESULTS

Immunohistochemical staining revealed that the marginal HBsAg was positive for pre-S1 and thus contained large surface proteins. The PCR cloning and sequencing of the genes presumably encoding marginal-type HBsAg in both cases revealed the same deletion at the 5' terminus (nt 2-55) of pre-S2. A point mutation on the small-surface (S) antigen was also found in one case. The pre-S2 deletion sequence and the mutation sites of the S gene coincide with human lymphocyte antigen-restricted T- and/or B-cell epitopes. In vitro transfection of the mutant plasmid revealed a blot-like retention or accumulation of HBsAg in the cytoplasm or at the periphery of hepatocytes, accompanied by a decreased secretion of HBsAg in the culture supernatant, mimicking intrahepatic expression.

CONCLUSION

A natural pre-S2 deletion mutant was identified in hepatocytes expressing a novel marginal pattern of HBsAg, which probably contains mutant, large, surface proteins. The biological significance of the pre-S2 deletion mutant should be interesting in view of the clustering proliferation of hepatocytes expressing marginal HBsAg.

Successful birth after intracytoplasmic sperm injection for severe male factor infertility in a woman with poor response to controlled ovarian hyperstimulation

Poor responders to controlled ovarian hyperstimulation (COH) present a clinical challenge for in vitro fertilization (IVF) and embryo transfer. The failure of IVF for the treatment of severe male-factor infertility can now be overcome by intracytoplasmic sperm injection (ICSI). The infertile couple documented in this case report came to our hospital because of bilateral tubal occlusion and severe oligoasthenospermia. After three poor-response cycles to COH, one mature oocyte was retrieved and was fertilized using ICSI. Normal fertilization ensued and one good-quality, eight-celled embryo was transferred into the woman's uterus. A single gestation was confirmed by ultrasound seven weeks after transfer. Amniocentesis was performed at 16 weeks and demonstrated a normal male fetus with a karyotype of 46,XY. The patient had a spontaneous, normal, vaginal delivery of a 2,650 g healthy male infant.

Prospective randomized comparison between pylorus-preserving and standard pancreaticoduodenectomy

BACKGROUND

Pancreaticoduodenectomy, with either gastrectomy (Whipple procedure) or pylorus-preserving pancreaticoduodenectomy (PPPD), is a complex procedure. Technical diversity, variation and sampling bias exist among surgeons. Previous reports comparing these two procedures are retrospective and not randomized. These factors should be considered seriously and eliminated in comparisons between the two procedures.

METHODS

From August 1994 to August 1997, a prospective randomized comparison was conducted between the Whipple procedure and PPPD performed by the same surgeon with the same approach and same anastomotic fashion for periampullary cancer. After exclusion of seven patients, 31 patients were eligible for the study, 16 receiving PPPD and 15 a Whipple procedure. No significant difference in the age, sex distribution, tumour localization or staging was noted between the two groups.

RESULTS

One operative death after PPPD and no operative death after the Whipple procedure resulted in a 3 per cent mortality rate in the 31 patients. Median duration of the Whipple operation was 235 (range 195-305) min, with a median blood loss of 500 (range 230-3100) ml and a median blood transfusion of 0 (range 0-10) units. In the patients who had PPPD, median operating time was 230 (range 170-275) min, median blood loss was 350 (range 100-1200) ml and median blood transfusion was 0 (range 0-4) units. There were two minor leaks from the pancreaticojejunostomy after the Whipple procedure and no leakage after PPPD, resulting in 6 per cent minor leakage in 31 patients. These outcomes were not significantly different. Delayed gastric emptying was observed more frequently after PPPD (six of 16 patients) than after the Whipple procedure (one of 15 patients), with marginal significance (P = 0.08, two-sided Fisher's exact test).

CONCLUSION

In this prospective randomized study, both PPPD and the Whipple procedure were associated with low mortality and operative morbidity rates. There was no significant difference between PPPD and Whipple resection in terms of operative mortality and morbidity, operating time, blood loss and blood transfusion. PPPD was associated with more frequent delayed gastric emptying, although study of more patients is needed to confirm this.

Immunolocalization of BRCA1 protein in normal breast tissue and sporadic invasive ductal carcinomas: a correlation with other biological parameters

AIM

BRCA1, a nuclear phosphoprotein, normally functions as a negative regulator of the cell cycle and may be an active inhibitor of neoplastic progression. Mutation of the BRCA1 gene has been demonstrated in 80% of familial breast cancer. Decreased mRNA levels or aberrant subcellular locations of BRCA1 have been identified in breast cancer lines and in sporadic cases of breast cancer tissues. The expression of BRCA1 in large series of variously differentiated breast carcinomas with correlation with other biological parameters has not been clarified.

METHODS AND RESULTS

The BRCA1 expression in normal breast tissue (n = 15) and in sporadic cases of invasive ductal carcinoma (n=108) was determined using immunohistochemistry. BRCA1 expression was correlated with other prognostic parameters including p53, c-erbB-2, bcl-2, oestrogen receptor (ER), histological grade, tumour size, axillary lymph node status and age. BRCA1 was exclusively (100%) localized in the nuclei of normal ductal and lobular epithelia. However, this nuclear expression pattern was variable in breast carcinoma (76.8%). Loss of nuclear BRCA1 expression (22 of 108 cases, 20.4%) correlated well with high histological grade (P<0.025) and bcl-2-negative tumours (P<0.05) and frequently in ER-negative tumours.

CONCLUSION

BRCA1 nuclear expression could be considered to represent the normal or physiological phenotype. Complete loss of BRCA1 nuclear expression in breast cancer and its correlation with other poor prognostic markers suggest that BRCA1 expression may play an important role in the pathogenesis and prognosis of sporadic breast carcinoma. Altered BRCA1 phenotype may therefore provide an additional prognostic parameter for breast cancer.

Benign retroperitoneal schwannoma mimicking a pancreatic cystic tumor: case report and literature review

A rare case of benign retroperitoneal schwannoma mimicking a pancreatic cystic tumor is reported herein. The tumor mass, based on a computed tomography scan and an abdominal echo examination, was initially suspected to be a mucinous cystadenoma or cystadenocarcinoma of the pancreas. However, the surgical and pathohistological findings made a final diagnosis of benign pancreatic schwannoma. The patient is doing well at a 2-year follow-up. The tumor, 18x17x15 cm in size, represented the largest among reported pancreatic schwannomas. Furthermore, a comprehensive review of reported cases of pancreatic schwannoma was carried out to summarize corresponding findings, including benign or malignant forms, adherence to other tissues, cystic change of the tumor, as well as relation to von Recklinghausen's neurofibromatosis.

Expression of fibroblast growth factor-1 and fibroblast growth factor-2 in normal liver and hepatocellular carcinoma

This study was performed to examine the immunohistochemical expression of fibroblast growth factor-1 and fibroblast growth factor-2 in normal liver and a total of 31 cases of hepatocellular carcinoma (HCC). Reactivity for both types of angiogenic factor did not exist in any cellular component of normal liver. For HCC, variable amounts of fibroblast growth factor-1 were detected in 6 of 31 cases (19.4%). There was no apparent relationship between the expression pattern and clinicopathologic factors (P > 0.1, respectively), except a positive correlation with histologic grading (P = 0.04). No tumor showed reactivity for fibroblast growth factor-2 in their cancer cells. However, both types of peptide could be demonstrated in the pericellular stroma of HCC. With a mean follow-up at 60 months, fibroblast growth factor-1 expression did not correlate with patients' outcome (P > 0.1). Our study suggested that fibroblast growth factor-1 appears to play a certain role in hepatocarcinogenesis.

Inflammatory pseudotumor of the liver in a patient with human immunodeficiency virus infection

A 31 year-old male was admitted for investigation of a hepatic tumor, which was incidentally found during abdominal sonography. Abdominal ultrasound revealed a large heterogeneous hyperechoic mass, 4x6x5cm in size, located at the inferior portion of the medial segment of the liver. Abdominal computed tomography without enhancement showed a hepatic tumor, 6 cm in size, in the medial segment of the liver. Malignancy was suspected in the light of radiological presentation. Therefore, wedge resection of the hepatic tumor was performed. The pathological findings revealed that the hepatic tumor was composed of dense fibrous tissue, plump spindle cells, foamy histiocytes, abundant lymphocytes, plasma cells and macrophages which led to the diagnosis of inflammatory tumor of the liver. The post-operative course was uneventful, and the patient was discharged two weeks after operation. Unfortunately, high fever and persisting headache were noted one week after discharge, thus the patient was re-admitted. The infectious focus was investigated during the second admission. Serological test for anti-human immunodeficiency virus was positive. Computed tomography of the brain revealed inflammatory changes over the territory of right middle cerebral artery. The patient died two weeks after the onset of encephalitis. We believe this to be the first case of inflammatory pseudotumor of the liver associated with human immunodeficiency virus infection.

Bezoar manifested with digestive and biliary obstruction

BACKGROUND/AIMS

Gastrointestinal obstructions caused by bezoars are uncommon but are encountered with increasing frequency in general surgery.

METHODOLOGY

We made a retrospective review of 30 cases treated in the National Cheng Kung University hospital between July 1988 and December 1994.

RESULTS

Fourteen patients had either prior gastric surgery (9) or peptic ulcer disease (5) and were categorized as group I. The remaining 16 patients without above conditions were categorized as group II; and seven of them had history of ingestion of Pho Pu Zi (Cordia dichotoma Frost. f.), three had food bolus ingestion, two had diverticulum, two had adhesion and the remaining two had no significant features. Two patients, who received endoscopic removal of gastric bezoar and subsequently developed bowel obstruction, needed operation. Sixteen of 30 who underwent operation within 24 hours after arrival, recuperated uneventfully and most were discharged within a week. Eleven patients who received operation after 24 hours resulted in prolonged hospitalization in 9 and death in two. Re-operation was performed in one case for the recurrence of obstruction by the residual bezoar.

CONCLUSION

Dietary factors (Pho Pu Zi or bolus ingestion), and gastrointestinal (GI) anatomical lesion (diverticulum or adhesion) are the profound etiologies for formation of bezoars in cases without previous gastric surgery. On the other hand, gastric factors (previous ulcer surgery or peptic ulcer) play a major role even after ingestion of nonspecific high fiber diet. Early diagnosis, surgical intervention without delay and thorough exploration of the entire GI tract are essential for good postoperative results.

Role of right hepatic lobectomy in the treatment of isolated right-sided hepatolithiasis

BACKGROUND

The role of right hepatic lobectomy is evaluated in the treatment of selected patients with isolated right-sided hepatolithiasis.

METHODS

During the past 7 years right hepatic lobectomy was performed in five patients who had isolated right-sided hepatolithiasis. The rationale and indications of this procedure are discussed. The efficacy of preoperative evaluations, the operative findings, and the operative results are analyzed.

RESULTS

All the patients were female with a mean age of 49.2 years (range, 33 to 63 years). The main symptoms were upper abdominal pain (n = 5), fever (n = 4), and jaundice (n = 2). The mean operative time was 166.4 minutes, and the mean blood loss was 880 ml. The complete stone clearance rate was 100%. No operative deaths occurred. Right subphrenic abscess with reactive pleural effusion developed in two patients. Echo-guided percutaneous drainage was applied to one patient, and no surgical intervention was needed. The mean follow-up period from the treatment was 13.4 months (range, 6 to 18 months). During the follow-up period no stone recurrence was found.

CONCLUSIONS

Right hepatic lobectomy is indicated in patients who have localized right-sided hepatolithiasis with irreversible biliary stricture involving the right hepatic duct, an atrophied right lobe of the liver, multiple cholangitic abscesses, or possible presence of cholangiocarcinoma. Preoperative evaluations, including cholangiography, abdominal ultrasonography, and computed tomography, are important for the accurate selection of patients and successful treatment.

A simple, secure and universal pancreaticojejunostomy following pancreaticoduodenectomy

Although the operative mortality of pancreaticoduodenal resection has decreased recently, the operative morbidity resulting from a leaking pancreatic anastomosis remains high. We described our experience in 50 consecutive cases with a simple, secure end to side pancreaticojejunostomy. We used a paediatric nasogastric tube in the pancreatic remnant duct as a temporary external pancreatic drain. There were 29 men and 21 women ranging from 12 to 84 years with a median age of 61 years. Forty-two patients underwent a standard Whipple procedure and eight a pylorus preserving pancreaticoduodenectomy. Average operating time was 270 minutes with a range of 170 to 480 minutes. The pancreaticojejunostomy could be constructed in a mean of 8 minutes. Intraoperative blood loss ranged from 150 to 3500 mL with a mean of 910 mL. Twenty-five patients (50%) received no blood transfusion. The consistency of the pancreatic remnant was hard in 12 patients (24%) and normal in 38 patients (76%). The pancreatic duct was dilated (> 4 mm) in 15 patients (30%). There was no operative mortality and only three (6.0%) minor leaks from the pancreatic anastomosis which healed spontaneously. It was difficult to determine if the leaks were related to the consistency of the pancreatic remnant, the size of the pancreatic duct, the amount of intraoperative blood loss, operating time, sex of the patient or experience of the surgeon, as there were only three leaks. We concluded that our technique for pancreaticojejunal anastomosis following pancreaticoduodenectomy was safe and applicable to, standard Whipple or pylorus preserving pancreaticoduodenectomy, small or dilated pancreatic ducts, normal or fibrotic pancreas.

Papillary cystic tumor of the pancreas in children

Papillary cystic tumor of the pancreas, so-called Frantz tumor, is a very rare tumor in children. Only 157 cases had been reported since 1959. The clinical manifestations of this disease are usually a slowly growing abdominal mass with or without abdominal pain. It occurs predominantly in young females, and its pathogenesis is still unknown. Surgical resection is usually curative, and its prognosis is excellent. Four adolescent girls with acute or chronic abdominal pain were found to have papillary cystic tumor of the pancreas at our hospital in the past 4 years. They all have a variable clinical presentation. Papillary cystic tumor of the pancreas should therefore be considered one of the differential diagnoses of abdominal pain or abdominal mass in adolescent girls.

A clinical study of 130 patients with biliary tract cancers and periampullary tumors

A retrospective review of 130 patients with peripheral-type cholangiocarcinomas (PTCC), hilar-type cholangiocarcinomas (HTCC), extrahepatic cholangiocarcinomas (EHCC), gallbladder cancers (GBCA), and periampullary cancers (PACA), seen at National Cheng Kung University Hospital and Tainan Municipal Hospital from June 1987 to July 1993 was performed. There were 47 (36%) HTCC, 32 (25%) PACA, 24 (19%) PTCC, 17 (13%) GBCA, and 10 (8%) EHCC patients. The distribution is completely different from that reported in western countries. These cancers mainly occur in elderly patients. HTCC and GBCA were predominantly noted in female patients. Biliary cancers in Taiwan were not related to liver fluke infestation, inflammatory bowel disease or hepatitis B virus infection. However, a close association with biliary lithiasis was found. The incidence of gallstones was 67, 39, 20, 29 and 19% for PTCC, HTCC, EHCC, GBCA and PACA, respectively. The most common presentation for PTCC and GBCA was abdominal pain, or jaundice for HTCC, EHCC and PACA. These symptoms correlate well with the location of the tumors. Among serum tumor markers, the elevation of CA19-9 was most frequent, occurring in 86% of the patients while CA125 and CEA occurred in 47% and 30% of the patients, respectively. During the course of disease, infection developed in 61% of the patients and was the main cause of death in 25%. Biliary tract infection and sepsis were the two leading manifestations and occurred in 49% and 32% of the patients, respectively. Overall survival was poor except in patients whose tumor could be completely resected.

Transverse abdominis musculo-peritoneal (TRAMP) flap for the repair of large duodenal defects

Definitive surgical management of major acute injuries to the second and third portions of the duodenum has been enigmatic. Sometimes, the defect is so large that it is unwise to do primary repair, and resection at this critical portion of the intestinal tract is technically hazardous or impossible. A serosal or mucosal patch technique has been used to repair this kind of duodenal defect with encouraging results. Since the use of this technique has proved effective, such a defect was not necessarily treated with the more complicated pancreaticoduodenectomy and was managed with less morbidity and mortality. But these techniques are still controversial. So, we tried a pedicle flap, called the transverse abdominis musculo-peritoneal (TRAMP) flap, for repair of large duodenal defect. We have used this flap in 25 rabbits, and the specimens were followed up to a period of 3 months. The flap showed satisfactory results and is presented as another option for repair of large duodenal defects.

Analysis of K-ras gene mutations in periampullary cancers, gallbladder cancers and cholangiocarcinomas from paraffin-embedded tissue sections

Point mutations of the K-ras gene were analyzed in 25 periampullary cancers (21 ampulla vater cancers, two common bile duct cancers and two duodenal cancers), two gallbladder cancers and six cholangiocarcinomas. DNA extracted from the paraffin-embedded tissues was amplified with the polymerase chain reaction and subsequently analyzed by direct cycle sequencing at codons 12, 13 and 18 of the K-ras gene. Codon 61 was first screened with single strand conformation polymorphism and then sequenced by direct cycle sequencing. No point mutation was found in any of the 25 periampullary cancers or the two gallbladder cancers. These results are similar to previous reports. Mutation of the K-ras gene seems not to play an important role in tumorigenesis of periampullary cancer. In two of six (33%) cholangiocarcinoma patients, point mutations were found. Both mutations were transitions, GGT to GAT at codon 12. The incidence of mutation was greater than that in Thailand (about 8%) but less than that in Japan (about 60%). Mutation of the K-ras gene may play varied roles in the tumorigenesis of cholangiocarcinoma, depending on geographic area.

Suprahepatic gallbladder and right lobe anomaly of the liver in patients with biliary cancers

The suprahepatic region is a rare ectopic location of the gallbladder. It usually combines with right lobe anomaly of the liver. Here we report two unusual cases of suprahepatic gallbladder with agenesis or hypogenesis of the right lobe of the liver and biliary cancer. A patient with a gallbladder tumor was admitted to our emergency room with acute cholecystitis and liver abscess. Imagining examinations and operation confirmed the suprahepatic position of gallbladder, agenesis of the right lobe, and dissemination of gallbladder cancer. In the patient with cholangiocarcinoma, CT scans and percutaneous transhepatic cholangiography documented the presence of a hilar tumor and hypogenesis of the right lobe. Both of these patients died from biliary tract cancer soon after operation.

Portal hemodynamics and humoral factors involved in a portal hypertensive rabbit model

Hemodynamic changes and certain humoral factors possibly responsible for splanchnic hyperemia in portal hypertensive rabbits created by partial portal vein ligation were studied. Portal pressure was significantly elevated after portal vein ligation and reached a climax on the second day. Then, it decreased but still remained at a plateau in a portal hypertensive state in the following days. Portal blood flow, measured with an electromagnetic flowmeter, had no significant change immediately after portal vein ligation and on post ligation day-1, but it increased significantly from the second day. Portal venous resistance rose significantly from the basal state immediately after portal vein ligation, then, it decreased from the second day, but still remained at a high resistance level as compared with the normal (p < 0.05). The levels of prostaglandin E2 and prostacyclin in the portal vein increased immediately after portal vein ligation but decreased on the second day. However, prostacyclin rose again on the fifth day. It is apparent from this study that once portal pressure or portal resistance increases, there is a surge of prostaglandin E2 and prostacyclin in the portal blood. Due to the vasodilation effect of prostacyclin, prostaglandin E2 and other possible vasodilators, portosystemic shunts are gradually produced, and splanchnic hyperemia develops in the portal hypertension. The initial mechanism of portal hypertension in this model was due mainly to an increase in resistance. At a later stage, increased splanchnic blood flow combined with increased resistance played an important role in the maintenance of portal hypertension.

Simple, effective procedure with few complications for esophageal varices

The surgical morbidity, mortality, and effectiveness of a modified nonshunting operation that includes splenic artery division instead of splenectomy, devascularization, and esophageal transection (SAD group) were evaluated. Eighteen cirrhotic patients with varices who underwent this modified procedure were compared with 54 patients treated with a conventional nonshunting operation (splenectomy group). Results show that immediate effects on portal pressure and preservation of portal perfusion between the two groups were similar. The operative time is shorter (p < 0.05), and the bleeding amount is less (p < 0.005) in the SAD group than in the splenectomy group. No surgical mortality and no major complications were noted in the SAD group. A surgical mortality of 2.3% and 30% was noted for the elective and emergency operations of the splenectomy group, respectively. There was no encephalopathy in the SAD group but one in the splenectomy group. Recurrent bleeding occurred in three patients of the splenectomy group 1 year after surgery but none in the SAD group. These data indicate that this modified procedure is a simple and effective operation with few complications for esophageal varices.

Measurement of organ volume by single photon emission computed tomography

The aim of this study was to develop a new algorithm for volume determination by single photon emission computed tomography (SPECT). Different algorithms were evaluated through phantom studies. The results show that the algorithm combining moment-preserving bilevel thresholding and best-fit Laplacian second derivative edge detection can provide the most accurate measurement of volume. Besides, this method can be utilized in different SPECT systems with no need for further phantom studies. In patient studies, the results of liver volume calculation have indicated that this is a useful technique in clinical medicine.

Effect of octreotide on hemodynamics and glucagon levels in portal hypertensive rabbits

This study was designed to investigate the effect of octreotide (Sandostatin, Sandoz), an analogue of somatostatin, on the hemodynamics and glucagon level in portal hypertension. Sixteen portal hypertensive rabbits produced by partial ligation of the portal vein two weeks earlier received an intravenous infusion of octreotide at a dose of 30 micrograms/h. After infusion of octreotide, a significant reduction in portal venous pressure from 16.2 +/- 3.9 mmHg (mean +/- SD) to 13.3 +/- 4.3 mmHg at 21 minutes and 12.0 +/- 4.5 mmHg 42 minutes was noted. A persistent decrease in portal pressure to 11.0 +/- 4.5 mmHg 21 minutes after stopping infusion of octreotide was also observed. Portal venous blood flow was decreased significantly from 60.9 +/- 13.1 mL/min to 46.9 +/- 15.0 ml/min at 21 minutes and to 45.8 +/- 12.8 ml/min at 42 minutes. A slight elevation of portal blood flow to 49.0 +/- 14.1 ml/min was noted 21 minutes after cessation of octreotide infusion. Portal venous resistance was slightly elevated during infusion of octreotide (before infusion: 2.2 +/- 1.4 dyne.s.cm-5, 21 minutes after infusion: 2.4 +/- 1.4 dyne.s.cm-5 and 42 minutes after infusion: 2.3 +/- 1.3 dyne.s.cm-5), and decreased (1.9 +/- 1.0 dyne.s.cm-5, p < 0.1) with a forward significance after stopping infusion. There were no significant changes in systemic arterial pressure during this experiment. A significant decrease (p < 0.05) in glucagon level from 323 +/- 93 pg/dl to 267 +/- 62 pg/dl at 21 minutes and to 298 +/- 88 pg/dl at 42 minutes in the portal vein was noted during the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of paraesophageal venous collaterals on efficacy of endoscopic sclerotherapy for esophageal varices

To determine the diagnostic accuracy of computer tomography in the detection of venous collaterals surrounding the esophagus in patients with portal hypertension, preoperative computer tomography interpretations of these veins in 15 patients who were candidates for the Sugiura procedure for treatment of esophageal varices were correlated with those of the intraoperative assessment. Laparotomy revealed severe paraesophageal varices in five patients; four of them were found to have paraesophageal varices in computer tomography films. The sensitivity and specificity of computer tomography in diagnosing severe paraesophageal varices were 80% and 100%, respectively. A second assessment was performed in 59 additional patients with esophageal variceal hemorrhage to investigate the influence of paraesophageal varices on the efficacy of endoscopic sclerotherapy in the treatment of varices. The patients were divided into two groups: Group A included 17 patients with and group B 42 patients without paraesophageal varices on presclerotherapy computer tomography. All patients underwent elective sclerotherapy after being deemed hemodynamically stable. Patients in group A required more treatment sessions, more sclerosant and longer periods to obliterate varices completely than did group B patients. Eight patients in group A and six in group B (57% vs. 16%, p < 0.05) had variceal recurrence after obliteration during mean follow-ups of 20.8 and 19.9 mo, respectively. The mean time elapsed before variceal reappearance was shorter for group A than for group B (4.1 +/- 3.3 vs. 11.8 +/- 2.7 mo, p < 0.05). Among patients who developed new varices, five patients in group A and one in group B experienced repeat bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical dissolution of gallstones in Taiwan: an in vitro study

To evaluate the potential for the chemical dissolution of gallstones, 480 stones from 214 patients were studied. The stones were obtained via surgery or endoscopically. They were classified into cholesterol-rich mixed stones, brown pigment stones and black stones. The composition of bilirubin and cholesterol was determined by Fourier transformed infrared spectroscopy. Two per cent tetrasodium ethylenediamine acetate (EDTA), dimethylsulfoxide (DMSO) or methyl-tert-butyl-ethylene (MTBE) were used to dissolve the stones. To enhance solubility, surfactant polysorbate-20 was used to mix two of the individual three solvents. Methyl-tert-butyl-ethylene was found to have the best dissolution ability (by dry weight) 94, 13.4 and 20% for mixed, brown and black stones, respectively. Dimethylsulfoxide resulted in 13, 14 and 25% dissolution and EDTA 9.5, 13 and 16.5%. In contrast, pure water dissolved 4, 6 and 10.4% of the stones, respectively. A combination of the dissolution agents did not enhance the dissolution rate. In fact, the combination of solvents unexpectedly reduced the solubility of the stones: EDTA/MTBE was 17.5, 6.7 and 16.0%; DMSO/MTBE 43.2, 21.9 and 18.0%; DMSO/EDTA 9.1, 7.0 and 9.6%. In conclusion, cholesterol-rich mixed stones were able to be dissolved using MTBE but results of contact dissolution for gallstones are still far from satisfactory.

Effects of splenectomy, devascularization and esophageal transection on portal venous pressure and portal perfusion in cirrhotic patients with bleeding esophageal varices

This investigation sought to determine the effects of splenectomy, devascularization and esophageal transection on portal venous pressure and portal perfusion in cirrhotic patients with a previous history of hemorrhage from esophageal varices. From June 1988 to June 1991, 54 patients with liver cirrhosis underwent this nonshunting procedure for esophageal varices. Of these patients, 24 patients (20 men and four women, 39 to 68 years of age, all in Child's class A) were examined for portal pressure before, during and after the nonshunting operations. Portal venous perfusion was assessed from the venous phase of the superior mesenteric arteriogram preoperatively and one year after surgery in 16 of these 24 patients. There was no significant change (p > 0.05) in cardiac output and systemic blood pressure after the operation. The portal venous pressure before surgery was 28.4 +/- 8.0 mmHg with a range from 18 to 44 mmHg. A statistically significant decrease (p < 0.05) in the portal pressure was observed after ligation of the splenic artery (26.6 +/- 8.9 mmHg), splenectomy (24.8 +/- 8.0 mmHg), and devascularization with transection (23.4 +/- 7.5 mmHg). No correlation between the portal pressure change and splenic weight was noted (p > 0.05). Postoperative portal perfusion remained the same or even improved in 15 of these 16 patients. Only in one patient was the portal perfusion worse after the operation; this patient developed encephalopathy about 18 months later. In conclusion, a significant reduction in portal pressure is noted after nonshunting procedures but a persistent, relatively high portal pressure is maintained. Good postoperative portal perfusion can also be maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergency endoscopic nasobiliary drainage for acute calculous suppurative cholangitis and its potential use in chemical dissolution

Acute suppurative cholangitis is one of the common causes of acute abdomen in Taiwan. Emergency decompression is a life-saving procedure if patients fail to respond to antibiotic treatment. From July 1988 to June 1991, 224 patients were encountered with concomitant bile duct stones and cholangitis; 40 were brought to the emergency service with shock or mental confusion or responded poorly to antibiotic treatment. The patients consisted of 20 males and 20 females aged 21-81 years (mean age 64 years); 55% had intrahepatic duct stones, 50% had positive blood culture, 38% had undergone previous biliary surgery, 25% had concomitant medical illnesses and 20% presented with mental confusion. Emergent endoscopic nasobiliary drainage (ENBD) was performed within 48 h of each patient's arrival in the emergency room. In 3 days all the patients exhibited significant improvement as defined by body temperature, vital signs, white blood cell count, serum bilirubin and alkaline phosphates levels. When their condition had stabilized, 21 patients underwent elective surgery. Six patients received ethylenediaminetetraacetic acid infusion through an ENBD tube. Two of the patients' stones dissolved completely. Six patients received papillotomy with stone removal. The remaining patients refused further treatment. There was no hospital mortality. It is therefore concluded that ENBD offers an effective treatment for acute calculus suppurative cholangitis and it is a potential route of administration for the chemical dissolution of bile duct stones.

Effects of splenectomy and splenic artery ligation on the portal pressure in portal hypertensive rats

Immediate, short-, and long-term effects of splenectomy and splenic artery ligation on the portal pressure were studied in animal models experimentally created by partial portal vein ligation. The portal pressure of these animals would usually elevate immediately after partial ligation of the portal vein from a normal level of 6.0 +/- 0.5 to 14.8 +/- 1.3 mm Hg (P < 0.005), which could be maintained at least for 6 months. The portal pressure measured at 2 weeks, 4 weeks, and 6 months after portal vein ligation was 14.0 +/- 2.7, 15.2 +/- 2.7, and 12.7 +/- 2.0 mm Hg, respectively (P < 0.005, as compared with the normal). When splenectomy was performed on these animals at 2 weeks after partial portal vein ligation, the pressure dropped immediately but only transiently from 14.0 +/- 2.7 to 11.0 +/- 3.0 mm Hg, and bounced back to the presplenectomy level in 20 sec. After an additional 2 weeks, the portal pressure in these splenectomized rats was usually at 15.2 +/- 4.2 mm Hg, which was indistinguishable from that of rats whose portal vein was ligated but the spleen was not removed. Six months after splenectomy, however, the portal hypertensive rats had a portal pressure of 17.1 +/- 6.4 mm Hg, which was significantly higher than that of the controls. Splenic artery ligation, on the other hand, did not result in any immediate decrease in portal pressure (14.0 +/- 2.7 mm Hg vs 14.6 +/- 1.4 mm Hg; P > 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of splenectomy on portal pressure in short- and long-term portal hypertensive rats

Different hemodynamic patterns were noted in short- and long-term portal hypertensive rats, induced by partial portal vein ligation (PVL) performed two weeks and six months earlier. In order to investigate the effect of splenectomy on the portal pressure of portal hypertensive rats with different hemodynamics, an operation was performed on these two groups of animals and the portal pressure measured thereafter at different time points. Splenectomy in the short-term group produced an immediate, but transient, drop in portal pressure from 14.1 +/- 2.7 to 11.0 +/- 3.0 mmHg, which bounced back to pre-splenectomy values in 20 seconds. Two weeks later, the portal pressure in these splenectomized rats was 15.2 +/- 4.2 mmHg, which was indistinguishable from that of the pre-splenectomy condition of the short-term group. However, after an additional two weeks, portal pressure in the splenectomized rats rose to 16.4 +/- 2.1 mmHg, which was significantly higher than that of the pre-splenectomy condition of the short-term group. This difference in portal pressure became even more pronounced at six months. Sustained portal hypertension was observed in the long-term group, but the pressure was significantly lower than that in the short-term group. Splenectomy in the long-term group produced neither an immediate drop nor a delayed rebound in portal pressure. We conclude that splenectomies in portal hypertensive rats at different stages of disease produce different effects.

Pancreas divisum with early pancreatic cancer--presenting as chronic obstructive pancreatitis

A 61-year-old man experienced four bouts of pancreatitis in 1 year. Detailed history taking and a series of examinations, including sonography, computed tomography scan, and endoscopic retrograde cholangiopancreatography (ERCP), revealed pancreas divisum on the first admission. He was treated conservatively. However, repeated ERCP on the fourth admission, 1 year later, showed a small filling defect in the tail of the pancreatic duct. A distal pancreatectomy was carried out. Pathological studies revealed a small papillary adenocarcinoma (1.5 x 1.0 x 0.5 cm) confined to the pancreatic duct grossly with minimal parenchymal invasion microscopically. He has been free from cancer and pancreatitis for 13 months since the operation.

A clinical pregnancy after a simple method of zona cutting, cryopreservation, and zygote intrafallopian transfer

A 30-year-old nulliparous woman, who was infertile for greater than 3 years, conceived after the procedures of a simple method of zona cutting, cryopreservation, and ZIFT. This case illustrates: (1) acid medium, chymotrypsin, or sucrose are not needed for the procedure of zona cutting; (2) the zygotes resulting from zona cutting survive through freezing and thawing; and (3) oocyte retrieval can be done concomitant with conservative surgery for endometriosis.

Lead, cadmium, arsenic, and mercury levels in maternal and fetal cord blood

In this study the levels of lead, arsenic, cadmium and mercury were measured by the method of graphite-furnace atomic absorption spectrophotometry in paired maternal and fetal cord blood (n = 168) collected from three cities in Taiwan, (Kaohsiung, Taipei and Keelung). The mean values of those heavy metals were within normal limits. There was no difference in levels by maternal parity or fetal sex. The mean value for the level of lead in maternal blood was 64.8 micrograms/L, and 40.9 micrograms/L for the umbilical-cord blood; comparing the three locations by ANOVA analysis, there was no difference in maternal or fetal blood levels. Mean maternal As concentrations (6.8 +/- 0.58 micrograms/L) and umbilical cord blood levels (7.9 +/- 0.67 micrograms/L) were within reference levels. The mean Cd concentrations in maternal blood were (1.30 micrograms/L) significantly higher than that of the umbilical-cord blood concentrations (0.78 micrograms/L). The maternal Cd concentrations (1.62 micrograms/L) of Kaohsiung were significantly higher than that (1.24 micrograms/L) of Taipei. The fetal Cd concentrations of Kaohsiung (1.04 micrograms/L) were also significantly higher than those (0.7 micrograms/L, 0.6 micrograms/L) of Taipei and Keelung. The mean umbilical-cord blood Hg concentration (28.8 micrograms/L) was higher than that (19.4 micrograms/L) of maternal blood. The maternal Hg concentrations of Taipei were significantly higher than those of Keelung. The fetal Hg concentrations (28.8 micrograms/L) of Taipei were also marginally higher than that of Keelung and Kaohsiung.

Hemodynamic changes after hepatectomy in rats studied with radioactive microspheres

It has been difficult to measure hepatic arterial blood flow and portal venous flow simultaneously, especially in small animals. Radioactive microspheres were used in this experiment to quantitate splanchnic hemodynamics after hepatectomy in rats. With a reference sample technique, a certain amount of radioactive microspheres was injected into the left ventricle. The reference sample was withdrawn from the femoral artery at a constant rate. The animal was killed with a bolus of saturated KCl. The kidneys and splanchnic organs were removed and weighed. The radioactivity of each organ was determined using a gamma scintillation counter. Organ blood flow was calculated by the following formula: [formula: see text] Immediately after partial hepatectomy, a decreased cardiac index from 32.31 +/- 10.12 to 23.44 +/- 3.21 ml/(min x 100g body weight) (p less than 0.05), decreased hepatic arterial blood flow from 0.40 +/- 0.12 to 0.33 +/- 0.03 ml/(min x g liver) (p less than 0.05), increased portal venous inflow from 0.90 +/- 0.30 to 2.20 +/- 0.26 ml/(min x g liver) (p less than 0.05) and increased total hepatic blood flow from 1.30 +/- 0.39 to 2.53 +/- 0.26 ml/(min x g liver) (p less than 0.005) were observed. With an intrasplenic injection of an additional amount of radioactive microspheres, the ratio of lung/(lung + liver) radioactivities indicated the degree of portal systemic shunt (PSS). Though the portal pressure was elevated after hepatectomy (8.80 +/- 0.7 vs 11.9 +/- 1.7 cm H2O, p greater than 0.05), the extent of PSS was negligible (0.02 +/- 0.01% vs 0.03 +/- 0.01%, p greater than 0.05). The radioactive microspheres with the reference sample technique is a simple, rapid, reliable and reproducible method for investigating the hemodynamic changes following partial hepatectomy.

A method for hepatic arterial perfusion studies in the rat

The current model for selective hepatic arterial infusion therapy was evaluated for its suitability for short-term pharmacokinetic experiments. This preparation consists of selective cannulation of the common hepatic artery via the gastroduodenal artery of the rat. Radioactive microspheres were injected to determine hepatic or extrahepatic sites of perfusion. Radioactive microsphere determination of hepatic arterial flow and cardiac output were also performed. Our data indicate that at high flow rates (2 ml/min), significant loss of drug would occur due to retrograde flow. Modification of the model to include temporary proximal hepatic artery occlusion ensures hepatic delivery of greater than 95% of drug. Furthermore, temporary hepatic artery occlusion does not alter cardiac output or hepatic arterial blood flow. Selective hepatic arterial infusion in rats with synchronous temporary hepatic artery occlusion is an adequate model for short-term pharmacokinetic studies.

Prostacyclin mediates splanchnic vascular response to norepinephrine in portal hypertension

Portal hypertension is characterized by increased splanchnic blood flow. This hyperemia may be related to the documented in vitro impaired sympathetic response in portal hypertension. Because prostacyclin (PGI2) has been shown to be elevated in portal hypertensive rabbits, we studied whether PGI2 could mediate the reduced sympathetic response. We measured the change in the superior mesenteric artery resistance (Rsma) to norepinephrine infusion in chronic portal vein ligated (PHT) and normotensive rabbits, in both portal hypertensives and normals following cyclooxygenase blockade with 8 mg/kg indomethacin, and finally in portal hypertensive, cyclooxygenase-blocked rabbits with a constant IV infusion of PGI2 at 200 or 300 ng/kg/min. Dose-response curves were obtained and statistical comparisons were based on the dose of norepinephrine producing 50% of maximal Rsma response (ED50). Portal hypertensive rabbits had significantly higher ED50 (310 +/- 4.1 mg/kg) than normotensive rabbits (150 +/- 4.1 mg/kg, P less than 0.01). Cyclooxygenase blockade resulted in marked reduction of the ED50 in both groups and ablated the difference between normotensive and PHT rabbits (20 +/- 2.4 and 20 +/- 2.8 mg/kg/min, respectively). Prostacyclin infusion at 200 ng/kg/min increased the ED50 (80 +/- 2.5 mg/kg) and PGI2 infusion at 300 ng/kg/min increased the ED50 further (160 +/- 7.5 mg/kg/min, P less than 0.01 vs cyclooxygenase-blocked only rabbits). These results provide the first in vivo evidence of reduced splanchnic sensitivity to norepinephrine in portal hypertension and demonstrate that PGI2 will cause a dose-related decrease in sympathetic response.(ABSTRACT TRUNCATED AT 250 WORDS)