CT pelvimetry and clinicopathological parameters in evaluation of the technical difficulties in performing open rectal surgery for mid-low rectal cancer

The present study aimed to evaluate the predictive value of pelvic anatomical and clinicopathological parameters for use in the estimation of the likely technical difficulties that may be encountered when performing open rectal surgery for mid-low rectal cancer. Sixty consecutive patients, undergoing open rectal surgery for mid-low rectal cancer were recruited between June 2009 and April 2014. All of the surgical procedures conducted, were low anterior resection (LAR) or abdominoperineal resection (APR). The operations were performed by the same surgeon and surgical team. Pelvic dimensions and angles were measured using three-dimensional reconstruction of spiral computerized tomography (CT) images. Operative time and intraoperative blood loss were used as indicators of operative difficulty. The independent variables were pelvic anatomical and clinicopathological parameters, and the dependent variables were operative time and intraoperative blood loss. Univariate and multivariate analyses were performed in order to determine the predictive significance of these variables. The pelvis width was significantly wider in females than in males (P<0.05), while the sacrococcygeal bending degree was significantly greater in males than in females (P<0.05). No significant difference were detected between the pelvis depth of females and males (P>0.05). Multivariate analyses showed that body mass index (BMI), tumor height, lymph node metastasis, anteroposterior diameter of the pelvic inlet, anteroposterior diameter of the pelvic outlet, height of the pubic symphysis, the sacrococcygeal distance, sacrococcygeal-pubic angle and diameter of the upper pubis to the coccyx were the main factors affecting the operative time (all P<0.05), while the maximum diameter of the tumor was the primary factor affecting intraoperative blood loss (P<0.05). Between the two procedures, the clinicopathological parameters appeared to be more valuable for predicting difficulty in LAR, in which operative time was associated with tumor height and tumor staging (R_C²=0.312; P<0.001). By contrast, the pelvic anatomical parameters appeared to be more valuable predictors of variation in APR, in which intraoperative blood loss was associated with the anteroposterior diameter of the mid-pelvis, the anteroposterior diameter of the pelvic outlet, the interspinous diameter, the depth of the sacral curvature and the sacropubic distance (R_C²=0.608; P=0.002). BMI, tumor height and the maximum diameter of the tumor may be used to predict the operative difficulty in performing open rectal surgery for mid-low rectal cancer. In addition to the associated clinicopathological parameters, wider, shallower and less curved pelvises may make the greatest contribution to reducing operative time and intraoperative blood loss. Operative difficulty is likely to be increased in deeper and narrower pelvises, or in those with greater sacrococcygeal curvature.

A 4-cm lipoma of the transverse colon causing colonic intussusception: A case report and literature review

Colonic lipomas are rare benign tumors. Colonic intussusception is an uncommon complication of colonic lipoma. The current study presents an unusual case of a 4-cm symptomatic lipoma of the transverse colon causing colonic intussusception. A 65-year-old female was admitted to Wenzhou Central Hospital (Wenzhou, Zhejiang, China) with intermittent pain in the left abdomen that had been present for two weeks. Colonoscopy revealed a 4×5-cm intraluminal spherical mass with erosional mucosa 60 cm above the anal verge, indicating the presence of a malignant gastrointestinal stromal tumor. Contrast-enhanced computed tomography revealed a well-defined fatty tissue mass of 4 cm in diameter in the distal transverse colon proximal to the splenic flexure, with intussusception. The patient underwent segmental resection of the transverse colon and intraoperative frozen sections were obtained. The intraoperative frozen sections revealed a submucosal lipoma of the transverse colon and thus, a conclusive diagnosis was achieved. The patient was followed up for one year and 10 months following the segmental resection of the transverse colon, with a good prognosis. This study may increase clinical awareness with regard to colonic lipomas. Furthermore, open surgery combined with use of intraoperative frozen sections should be recommended for large symptomatic colonic lipomas accompanied by colonic intussusception, thus avoiding unnecessary radical resection and improving patient prognosis.

Extended criteria donor and severe intraoperative glucose variability: association with reoperation for hemorrhage in liver transplantation

Reoperations for hemorrhage following liver transplantation (OLT) are commonly associated with increased morbidity and mortality. We sought to determine the incidence and risk factors for reoperation for hemorrhage among adult liver transplantations. We retrospectively analyzed 668 patients transplanted between January 2004 and November 2007. Within 30 days following transplantation one hundred eleven patients (16.6%) underwent 156 reoperations for hemorrhage, averaging 1.4 reoperations per patient. More than half of the reoperations occurred during the first 2 postoperative days. One-third of patients required 2 or more reoperations. Multivariate logistic regression analysis showed 4 independent risk factors: grafts from donors with multiple extended criteria, severe intraoperative glucose variability, intraoperative use of vasopressors, and red blood cell transfusion requirement. In conclusion, we identified several independent risk factors for reoperation due to hemorrhage following OLT. Avoidance of severe intraoperative glucose variability and careful evaluation of the benefits and risks of utilizing extended criteria donors must be considered before transplantation.

Management of ascites

The evaluation of ascites includes a directed history, focused physical examination, and diagnostic paracentesis with ascitic fluid analysis. Dietary sodium restriction and oral diuretics are the mainstay of therapy for the majority of patients with cirrhotic ascites. Transjugular intrahepatic portocaval shunt has emerged as the treatment of choice for selected patients with refractory ascites, although serial large-volume paracenteses should be attempted first. Early diagnosis, broad-spectrum antibiotics, and albumin infusion contribute to the successful management of spontaneous bacterial peritonitis (SBP). Referral for liver transplant evaluation should be considered at the first sign of decompensation and should not be delayed until development of ominous clinical features, such as refractory ascites and SBP.

Hyperfibrinolytic activity in hospitalized cirrhotic patients in a referral liver unit

OBJECTIVE

Increased frequency of hyperfibrinolytic activity was reported in patients with cirrhosis. However, the incidence, clinical presentation, and the parameters related to hyperfibrinolysis remain largely unknown in these patients. By utilizing euglobulin lysis time (ELT) and other clinical coagulation tests, the present study investigated the incidence of and clinical parameters related to hyperfibrinolytic activity, and assessed predicting factors to epsilon-aminocaproic acid (EACA) treatment in cirrhotic patients with hyperfibrinolysis in a liver unit.

METHODS

The study included 86 consecutive patients who were referred and admitted to a referral liver unit for various liver diseases. The mean age was 50.0 yr, with a male: female ratio of 60:26. Sixty-six patients (76.7%) were Hispanic and 75 (87.2%) were cirrhotic. The etiologies of liver diseases included alcoholic liver disease (n = 68, 79.1%), hepatitis B (n = 2, 2.3%), hepatitis C (n = 6, 7.0%), autoimmune hepatitis (n = 3, 3.5%), cryptogenic liver disease (n = 4, 4.7%), and hepatocellular carcinoma (n = 3, 3.5%). Coagulation studies included ELT, PT, PTT, fibrinogen, D-dimer, and fibrin degradation product levels.

RESULTS

Hyperfibrinolytic activity as reflected by shortened ELT was present in 27/75 cirrhotic (31.3%) but 0/11 noncirrhotic patients, which was significantly correlated with higher Child-Pugh (C-P) class, abnormal levels of PT, PTT, fibrinogen, platelet count, and total bilirubin. Shortened ELT was more frequently seen in patients with hepatic decompensation and mucocutaneous bleeding, although these relationships were not statistically significant. In 27 patients with hyperfibrinolysis, five (18.5%) required EACA treatment for progressive mucocutaneous bleeding and/or hematoma. EACA treatment was significantly associated with higher C-P scores; greatly shortened ELT (< or =50% of normal value); and abnormal levels of fibrinogen, total bilirubin, and PT, indicating that these factors may serve as predictors for EACA treatment.

CONCLUSION

Hyperfibrinolytic activity was seen in 31.3% of patients with cirrhosis, which is correlated with higher C-P scores; abnormal PT, PTT, fibrinogen level, and platelet count; and hyperbilirubinemia. Patients who received EACA treatment usually have a more severe hyperfibrinolytic activity as indicated by shortened ELT and low level of fibrinogen, and more severe liver disease as indicated by higher C-P scores and hyperbilirubinemia.

Viral, host and interferon-related factors modulating the effect of interferon therapy for hepatitis C virus infection

The estimated prevalence of hepatitis C virus infection in the US is approximately 1.8%. Although interferon monotherapy and combination therapy of interferon with ribavirin represent mainstay for treating HCV infection, the rate of sustained virologic response remains suboptimal. The growing evidence suggested that the clinical sequence and treatment response of chronic hepatitis C are determined by a dynamic, complex tripartite relationship among HCV infection, the host immune response, and the effect of different interferon regimens. The treatment response is associated with various viral factors including the pretreatment viral level, dynamic change of viral level during treatment, viral genotype quasispecies and nucleotide mutation in nonstructural protein 5A of hepatitis C virus. Host factors that may affect treatment response include age, gender, race, HLA alleles and the host immune responses. Interferon regimens, including type, dose, frequency and duration of treatment and combination of interferon with other anti-HCV agents also alter the therapeutic response. Understanding these complicated interaction may provide better insights into the mechanism(s) of interferon response, leading to more effective clinical application of interferon therapy.

The adhesion signaling molecule p190 RhoGAP is required for morphogenetic processes in neural development

Rho GTPases direct actin rearrangements in response to a variety of extracellular signals. P190 RhoGAP (GTPase activating protein) is a potent Rho regulator that mediates integrin-dependent adhesion signaling in cultured cells. We have determined that p190 RhoGAP is specifically expressed at high levels throughout the developing nervous system. Mice lacking functional p190 RhoGAP exhibit several defects in neural development that are reminiscent of those described in mice lacking certain mediators of neural cell adhesion. The defects reflect aberrant tissue morphogenesis and include abnormalities in forebrain hemisphere fusion, ventricle shape, optic cup formation, neural tube closure, and layering of the cerebral cortex. In cells of the neural tube floor plate of p190 RhoGAP mutant mice, polymerized actin accumulates excessively, suggesting a role for p190 RhoGAP in the regulation of +Rho-mediated actin assembly within the neuroepithelium. Significantly, several of the observed tissue fusion defects seen in the mutant mice are also found in mice lacking MARCKS, the major substrate of protein kinase C (PKC), and we have found that p190 RhoGAP is also a PKC substrate in vivo. Upon either direct activation of PKC or in response to integrin engagement, p190 RhoGAP is rapidly translocated to regions of membrane ruffling, where it colocalizes with polymerized actin. Together, these results suggest that upon activation of neural adhesion molecules, the action of PKC and p190 RhoGAP leads to a modulation of Rho GTPase activity to direct several actin-dependent morphogenetic processes required for normal neural development.

Acute hepatitis induced by bupropion

As an antidepressant, bupropion is considered to be a safe agent that usually causes infrequent and mild increase of serum liver enzymes. Asymptomatic elevation of serum transaminases was previously reported only in a single case. We describe a patient who developed typical acute hepatitis after receiving six weeks of bupropion for depression. His presentation was characterized with acute onset of symptoms associated with significantly elevated ALT, AST, and LDH and acute hepatic inflammation. The clinical course of our patient, including incubation period, pattern of liver enzyme elevation, and time of recovery, was similar to, but much more severe than, the case reported by Oslin and Duffy. Discontinuation of bupropion was followed by a rapid resolution of clinical symptoms and liver enzymes. The incidence of bupropion-induced hepatitis remains to be defined even though it appears to be relatively low. Since the clinical application of bupropion is broader, we must be aware of the clinical entity of bupropion-induced hepatitis.

The long-term outcomes of patients with compensated hepatitis C virus-related cirrhosis and history of parenteral exposure in the United States

It is well known that hepatitis C virus (HCV) infection may progress to cirrhosis and is linked to the development of hepatocellular carcinoma (HCC). Previous studies have shown that compensated HCV-cirrhosis is related to a certain morbidity and mortality in European patients, but little is known in regard to the clinical outcomes of a similar group of patients in the United States. This study investigated this category of patients in terms of the incidence of decompensation, development of HCC, mortality, and the predictive risk factors for morbidity and mortality. The potential effects of interferon (IFN) therapy on outcomes of the disease also were assessed. A total of 112 patients with compensated HCV-cirrhosis and a documented history of either intravenous drug abuse (IVDA) or transfusion were consecutively enrolled. The mean follow-up interval was 4.5 (2-7.7) years. The cumulative probabilities for decompensation and development of HCC were 22.2% and 10.1% in 5 years, with an estimated yearly incidence of 4.4% and 2.0%, respectively. The cumulative survival probability was 82.8% from entry and 51.1% from decompensation in 5 years, with estimated yearly events of mortality and liver transplantation of 3.4% and 9. 8%, respectively. It was found that age at entry and initial exposure, initial levels of albumin, platelet count, and prothrombin time (PT) were predictive risk factors for developing decompensation, whereas age at entry and initial exposure, history of transfusion, lower initial levels of albumin, platelet count, and viral load were predictive risk factors for events of mortality and liver transplantation. The incidence of decompensation was significantly lower in patients treated with IFN, but age may have played a contributory role. In contrast, neither HCC development nor mortality was significantly altered by IFN therapy. In conclusion, our study indicated that patients with compensated HCV-cirrhosis in the United States progressed slowly and experienced eventual morbidity and mortality. Once decompensation develops, the disease will be more progressive and result in even higher mortality. Further studies will be required to determine the efficacy of IFN on clinical outcomes in this group of patients.

Myoblast city, the Drosophila homolog of DOCK180/CED-5, is required in a Rac signaling pathway utilized for multiple developmental processes

The Rac and Cdc42 GTPases share several regulators and effectors, yet perform distinct biological functions. The factors determining such specificity in vivo have not been identified. In a mutational screen in Drosophila to identify Rac-specific signaling components, we isolated 11 alleles of myoblast city (mbc). mbc mutant embryos exhibit defects in dorsal closure, myogenesis, and neural development. DOCK180, the mammalian homolog of Mbc, associates with Rac, but not Cdc42, in a nucleotide-independent manner. These results suggest that Mbc is a specific upstream regulator of Rac activity that mediates several morphogenetic processes in Drosophila embryogenesis.

Tandem SH2 binding sites mediate the RasGAP-RhoGAP interaction: a conformational mechanism for SH3 domain regulation

Many cellular signaling proteins contain SH3 (Src homology 3) domains that mediate protein interactions via specific proline-containing peptides. Unlike SH2 domains, whose interactions with tyrosine-containing peptides are promoted by phosphorylation of the SH2 binding site, the regulatory mechanism for SH3 interactions is unclear. p120 RasGAP (GTPase-activating protein), which contains an SH3 domain flanked by two SH2 domains, forms an abundant SH2-mediated complex with p190 RhoGAP in cells expressing activated tyrosine kinases. We have identified two closely linked tyrosine-containing peptides in p190 that bind simultaneously to the RasGAP SH2 domains upon p190 phosphorylation. This interaction is expected to bring the two SH2 domains into close proximity. Consequently, RasGAP undergoes a conformational change that results in a 100-fold increase in the accessibility of the target binding surface of its SH3 domain. These results indicate that the tandem arrangement of SH2 and SH3 domains found in a variety of cellular signaling proteins can provide a conformational mechanism for regulating SH3-dependent interactions through tyrosine phosphorylation. In addition, it appears that the role of p190 in the RasGAP signaling complex is to promote additional protein interactions with RasGAP via its SH3 domain.

Identification of a novel human Rho protein with unusual properties: GTPase deficiency and in vivo farnesylation

We have identified a human Rho protein, RhoE, which has unusual structural and biochemical properties that suggest a novel mechanism of regulation. Within a region that is highly conserved among small GTPases, RhoE contains amino acid differences specifically at three positions that confer oncogenicity to Ras (12, 59, and 61). As predicted by these substitutions, which impair GTP hydrolysis in Ras, RhoE binds GTP but lacks intrinsic GTPase activity and is resistant to Rho-specific GTPase-activating proteins. Replacing all three positions in RhoE with conventional amino acids completely restores GTPase activity. In vivo, RhoE is found exclusively in the GTP-bound form, suggesting that unlike previously characterized small GTPases, RhoE may be normally maintained in an activated state. Thus, amino acid changes in Ras that are selected during tumorigenesis have evolved naturally in this Rho protein and have similar consequences for catalytic function. All previously described Rho family proteins are modified by geranylgeranylation, a lipid attachment required for proper membrane localization. In contrast, the carboxy-terminal sequence of RhoE predicts that, like Ras proteins, RhoE is normally farnesylated. Indeed, we have found that RhoE in farnesylated in vivo and that this modification is required for association with the plasma membrane and with an unidentified cellular structure that may play a role in adhesion. Thus, two unusual structural features of this novel Rho protein suggest a striking evolutionary divergence from the Rho family of GTPases.

Detection of hepatitis C virus with RNA polymerase chain reaction in fulminant hepatic failure

The role of hepatitis C virus (HCV) infection in fulminant hepatic failure is controversial. The frequency of serum HCV RNA positivity in previously reported patients with fulminant hepatic failure (FHF) of indeterminate cause ranged from 0 to 12% in the United States and Europe and from 43% to 59% in Asia. We assessed serum HCV RNA using polymerase chain reaction (PCR) and oligoprimers from the 5'UTR of the HCV genome in 26 consecutive patients with FHF. Another laboratory independently performed PCR on 21 of the serum samples using different oligoprimers from the 5'UTR and NS3 region of the HCV genome. Serum HCV RNA was detected in two of seven (28%) patients with hepatitis B, 9 of 15 (60%) with an indeterminate cause, and in none with hepatitis A (n = 2) or drug-induced hepatotoxicity (n = 2). HCV RNA PCR results were concordant between both laboratories in 17 of 21 (81%) of samples. In patients with an indeterminate cause, HCV RNA positivity was significantly associated with the transmission risk factor of low socioeconomic status and Hispanic ethnicity. Eighteen patients underwent liver transplantation (LT) and 15 (83%) survived. Among patients with FHF of indeterminate cause, recurrent or acquired HCV infection after transplantation occurred in three of five (60%) and one of four (25%) patients, respectively. Three of four (75%) patients with hepatitis C virus infection post-LT also developed histologic hepatitis. HCV appears to be the causative agent of a substantial number of cases of FHF classified as indeterminate in the Los Angeles area. Differences in patient populations or risk factors may explain the discordant incidences of HCV infection in FHF observed among different programs.

Simultaneous detection of both hepatitis B virus DNA and hepatitis C virus RNA using a combined one-step polymerase chain reaction technique

Hepatitis C virus (HCV) RNA polymerase chain reaction (PCR) is widely used for diagnosis of HCV infection and evaluation of therapy. The sensitive hepatitis B virus (HBV) DNA PCR is often reserved for detection of quantities of HBV DNA that are insufficient for hybridization. Application of both PCR techniques is limited by their labor-intensity, potential for contamination, and substantial time required for analysis. To study HCV and HBV infections, occurring alone or in combination, we developed a combined one-step PCR method to detect HCV RNA and HBV DNA in a single serum specimen using oligoprimers from the HCV 5' untranslated region and the HBV preS/S region. Specificity of the HBV and HCV PCR products was confirmed on the basis of their molecular sizes in positive samples, Southern blot hybridization, and negative controls. The sensitivities of the combined PCR were assessed using samples containing a wide range of defined amounts of HBV DNA and HCV RNA and were comparable with those obtained with conventional HBV DNA or HCV RNA PCR methods. The sensitivity of the combined method was further validated by the 100% concordance between results of its HBV and HCV components and those of conventional PCR methods in patients with HBV and/or HCV infections. The combined one-step HBV/HCV PCR is a sensitive, specific, rapid, and cost-effective method, especially suited for epidemiological screening and clinical diagnosis of HBV and HCV infections occurring alone or in combination.

Characterization of rho GTPase family homologues in Drosophila melanogaster: overexpressing Rho1 in retinal cells causes a late developmental defect

The rho family of GTPases has been implicated in regulating changes in cell morphology in response to extracellular signals. We have cloned three widely expressed members of this family from Drosophila melanogaster; a rho homologue (Rho1) and two rac homologues (Rac1 and Rac2). Flies harbouring a Rho1 transgene that is specifically expressed in the eye exhibit a dramatic dose dependent disruption of normal eye development. Flies bearing at least two copies of the transgene display a severe rough eye phenotype characterized by missing secondary and tertiary pigment cells, a substantial reduction in the number of photoreceptor cells and a grossly abnormal morphology of the rhabdomeres. Cell fate determination in the imaginal disc occurs normally and abnormalities become manifest late in pupariation, coincident with the phase when the cells undergo major morphological changes. This phenotype is modified by mutations at several other loci that have been implicated in signal transduction, but not by mutations in ras pathway components.

p190 RhoGAP, the major RasGAP-associated protein, binds GTP directly

In mitogenically stimulated cells, a specific complex forms between the Ras GTPase-activating protein (RasGAP) and the cellular protein p190. We have previously reported that p190 contains a carboxy-terminal domain that functions as a GAP for the Rho family GTPases. Thus, the RasGAP-p190 complex may serve to couple Ras- and Rho-mediated signalling pathways. In addition to its RhoGAP domain, p190 contains an amino-terminal domain that contains sequence motifs found in all known GTPases. Here, we report that p190 binds GTP and GDP through this conserved domain and that the structural requirements for binding are similar to those seen with other GTPases. While the purified protein is unable to hydrolyze GTP, we detect an activity in cell lysates that can promote GTP hydrolysis by p190. A mutated form of p190 that fails to bind nucleotide retains its RasGAP binding and RhoGAP activities, indicating that GTP binding by p190 is not required for these functions. The sequence of p190 in the GTP-binding domain, which shares structural features with both the Ras-like small GTPases and the larger G proteins, suggests that this protein defines a novel class of guanine nucleotide-binding proteins.

Characterization of phorbol ester-stimulated serine phosphorylation of the human insulin receptor

Phorbol 12-myristate 13-acetate (PMA)-stimulated phosphorylation of the human insulin receptor (IR) was characterized and compared in two cell types of different lineage: normal rat kidney epithelial (NRK) cells and Chinese hamster ovary (CHO) fibroblasts. PMA stimulation increased IR beta-subunit phosphorylation to 252 +/- 43 and 25- +/- 47% (+/- S.D.) of the unstimulated control in NRK and CHO cells respectively. Tryptic phosphopeptide analysis by Tricine/SDS/PAGE revealed significant differences in the PMA-stimulated phosphorylation of the IR in these two cell types. This phosphorylation of the IR was predominantly located in two tryptic phosphopeptides, and these phosphopeptides were absent in an IR mutant truncated by 43 C-terminal amino acids. The major PMA-stimulated tryptic phosphopeptide from in vivo-labelled CHO/IR was immunoprecipitated with an antibody against residues Ser1315 to Lys1329, and this precipitation was blocked with excess unlabelled peptide containing this sequence. Radiosequencing by manual Edman degradation revealed that this tryptic phosphopeptide was phosphorylated at Ser1315. This PMA-stimulated phosphorylation did not inhibit autophosphorylation of the IR in vivo. These results demonstrate that PMA-stimulated phosphorylation of the IR can exhibit significant differences when expressed in different cell types, and that Ser1315 is a major PMA-stimulated phosphorylation site on the human IR.

Molecular diagnostic techniques for viral hepatitis

The five different viruses that cause human viral hepatitis, A, B, C, D, and E share the unique property of hepatotropism. Identification of the nucleic acid sequences of each of these viruses, coupled with the application of recombinant DNA technology, has resulted in the rapid development of molecular diagnostic techniques. Currently, molecular hybridization and polymerase chain reaction are the major diagnostic techniques for viral hepatitis. This review discusses the molecular biology of the five hepatitis viruses, the principles of molecular biological techniques, and their current and future diagnostic applications.

One-step RNA polymerase chain reaction for detection of hepatitis C virus RNA

Although detection of hepatitis C virus RNA with polymerase chain reaction has become the standard for diagnosis, extensive application has been thwarted by polymerase chain reaction's labor intensiveness, risk of false-positive results through contamination and time required for individual assays. To minimize these limitations, we developed and validated a one-step hepatitis C virus RNA polymerase chain reaction assay. The one-step method was compared with traditional hepatitis C virus RNA polymerase chain reaction using primers from the highly conserved 5' untranslated region of the hepatitis C virus genome. Variables studied in the one-step method included the source and quantity of reverse transcriptase (RTase), the concentration of MgCl2 and the duration of reverse transcription and complementary DNA amplification cycles. Optimal conditions for the one-step method were obtained with 25 U of reverse transcriptase and 2 mmol/L MgCl2. The one-step method substantially reduced the time required for analysis. The sensitivity of the one-step method was comparable to that of traditional hepatitis C virus RNA polymerase chain reaction using serially diluted RNA extracted from the serum of a hepatitis C virus-infected patient. The specificity of the one-step method was confirmed on Southern-blot hybridization. The results exhibited 100% concordance with results of traditional hepatitis C virus RNA polymerase chain reaction in 50 serum samples, including those of positive and negative controls. In addition, 100% concordance was observed between the two methods' results when sera containing low levels of hepatitis C virus RNA were used.(ABSTRACT TRUNCATED AT 250 WORDS)

Up-regulation of intercellular adhesion molecule 1 transcription by hepatitis B virus X protein

Intercellular adhesion molecule 1 (ICAM-1), a counter-receptor for lymphocyte function-associated antigen 1 on T cells, is critically important to a wide variety of adhesion-dependent leukocyte functions, including antigen presentation and target cell lysis. ICAM-1 expression by hepatocytes is increased in areas of inflammation and necrosis during chronic hepatitis B. Whether induction of ICAM-1 is due to the effect of inflammatory cytokines or involves a direct effect of the hepatitis B virus (HBV) remains unknown. In the present study, transfection of the HBV genome into human hepatoma cell lines resulted in enhanced expression of ICAM-1 protein and RNA in the absence of inflammation. Results of subgenomic transfections indicated that the HBV X protein (pX) induced ICAM-1 expression. Nuclear run-on assays showed that pX induced the ICAM-1 gene by increasing its rate of transcription. Although both pX and interferon gamma induced transcription of ICAM-1, addition of interferon gamma to cells expressing pX did not show an additive or synergistic effect. These results indicate that pX can directly regulate expression of ICAM-1 and may participate in the immunopathogenesis of HBV infection.

Direct detection of circulating hepatitis C virus RNA using probes from the 5' untranslated region

Diagnostic testing for hepatitis C virus (HCV) infection currently is based on the presence of anti-HCV antibodies or a positive HCV RNA polymerase chain reaction (PCR) test. Although HCV RNA PCR is a sensitive and specific technique, widespread application is limited. Moreover, HCV RNA PCR is subject to false-positive reactions through contamination and is inherently difficult to standardize and quantitate. To overcome limitations of HCV RNA PCR, we produced both cDNA and riboprobes from a 241 nucleotide sequence of the 5' untranslated region of the HCV genome for slot hybridization. Hybridization was absent using normal human serum, horse serum, or hepatic cellular RNA from noninfected liver. Hybridization occurred predominantly with positive-stranded HCV RNA and was abolished by pretreatment with RNase A. Slot hybridization was performed on serum samples from 60 patients with chronic HCV infection and a positive HCV RNA PCR and 20 patients with liver diseases unrelated to HCV who had a negative HCV RNA PCR. Slot hybridization with cDNA and riboprobes showed concordance with HCV RNA PCR of 95 and 98.3%, respectively. There were no false-positive reactions in controls. The sensitivity of riboprobe hybridization was comparable to that of one stage HCV RNA PCR using 5' untranslated region primers. Riboprobe hybridization with the HCV H strain standard was positive in the dilution corresponding to 10(-6) chimpanzee infectious doses50/ml. The density of the hybridization signals correlated significantly with the mass of an RNA standard extracted from the liver of a patient with HCV infection. The relative quantities of HCV RNA in the sera of selected patients varied and were not correlated with the duration of disease or the histopathological stage. The highest relative quantities were associated with concurrent immunosuppression. We conclude that slot hybridization is a sensitive, specific alternative to HCV RNA PCR that can be directly quantitated using appropriate HCV RNA standards.

Transcriptional factor C/EBP binds to and transactivates the enhancer element II of the hepatitis B virus

The human hepatitis B Virus genome (HBV) contains a liver-specific enhancer upstream of the X ORF which has been studied in detail by several investigators. A second liver-specific enhancer element, designated here as enhancer II, has been relatively recently described in the HBV genome, which is located within the core/pregenomic promoter. We have studied the interactions of transcriptional factors with this element and show here that the nuclear factor CCAAT/enhancer binding protein (C/EBP) binds at a unique site within these sequences. Further, using the transient cotransfection scheme of expression with C/EBP encoding vectors and an enhancer II-reporter gene construct, we demonstrate that the enhancer element II responds to increasing amounts of C/EBP by displaying transactivation. Evidence for the functional role of the enhancer element II in transcriptional regulation of the HBV gene expression is presented. A major influence of the enhancer II appears to be on the surface antigen expression.

Regulation of the hepatitis B virus gene expression by the enhancer element I

Hepatitis B virus (HBV) enhancer is a cis-acting element capable of potentiating transcription with liver cell specificity. To assess the regulatory function of the enhancer during viral gene expression, we employed whole genome transfections in both liver- and non-liver-derived cell lines and compared them with those of enhancerless genome transfections. Using a transient scheme of expression, the effect of enhancer deletion on the transcription of HBV genes was investigated. S1 nuclease analysis showed that deletion of the enhancer sequences did not alter the specificity of the HBV transcripts. Also, the nuclear run-on analysis demonstrated that the influence of enhancer on the HBV gene expression is at the transcriptional level. We further noted that in the absence of the enhancer, synthesis of the pregenomic RNA which originates from the core/pregenomic promoter was markedly affected. This result then implicates an additional role of the enhancer during the replication of HBV.

Trans-activation of HLA-DR gene by hepatitis B virus X gene product

Hepatocellular injury during hepatitis B virus (HBV) infection has been postulated to result from a human leukocyte antigen (HLA)-restricted T-lymphocyte host immune response against HBV antigens. Although HLA expression is enhanced in the presence of hepatic inflammation, whether HBV itself can induce HLA expression on infected hepatocytes is unknown. In this study, we demonstrate the induction of HLA-DR expression on human hepatoma cell lines transfected with HBV DNA sequences. The HBV X gene alone was capable of inducing HLA-DR expression. This induction correlated with elevated HLA-DR RNA, and this resulted directly from transcriptional trans-activation of the HLA-DR gene by the HBV X protein. These studies suggest that the HBV X protein can regulate the expression of HLA-DR and thus raise the possibility of participation by the X gene in the immunopathogenesis of HBV infection.

Modulation of the insulin growth factor II/mannose 6-phosphate receptor in microvascular endothelial cells by phorbol ester via protein kinase C

Phosphorylation of hormone receptors by protein kinase C (PKC) may be involved in the regulation of receptor recycling. We have studied the recycling and the phosphorylation state of the insulin growth factor (IGF) II/mannose 6-phosphate (Man-6-P) receptor in microvascular endothelial cells from rat adipose tissue. Scatchard analysis showed these cells have over 2 x 10(6) receptors/cell with an affinity constant of 1 x 10(9) M-1. In the presence of phorbol myristate acetate (PMA), an activator of PKC and analog of diacylglycerol, IGF-II receptor number increased in the plasma membrane by 60% without changes in the binding affinity. This increase in cell surface receptor number was confirmed by affinity cross-linking and 125I-surface labeling studies, occurred with a half-time of 20 min, and was reversible upon withdrawal of PMA. The redistribution of IGF-II/Man-6-P receptors was not due to an inhibition of internalization which was in fact stimulated by PMA. The effect of PMA on IGF-II receptor recycling correlated with its stimulation of PKC activity. Furthermore, after down-regulation of cellular PKC levels by preincubation with PMA, PMA was unable to activate residual PKC activity in the membranous pool or increase IGF-II receptor number at the cell surface. The phosphorylation state of the IGF-II/Man-6-P receptor was determined by 32P labeling of intact cells and immunoprecipitation with anti-receptor antibodies. In the basal state, the receptor was phosphorylated only on serine residues which was increased by 75% after treatment with PMA. In contrast, IGF-II decreased receptor phosphorylation and plasma membrane binding in a parallel and dose-dependent manner. Thus, PKC-stimulated serine phosphorylation of IGF-II/Man-6-P receptor may promote the translocation of the receptor to the cell surface, whereas IGF-II-stimulated dephosphorylation of the receptor may lead to a decrease in the number of cell surface receptors. These data suggest a role for PKC-mediated serine phosphorylation in the regulation of intracellular trafficking of receptors in endothelial cells.

Multiple liver-specific factors bind to the hepatitis B virus core/pregenomic promoter: trans-activation and repression by CCAAT/enhancer binding protein

The human hepatitis B virus (HBV) is a hepatotropic virus that replicates through an RNA intermediate referred to as the pregenome. The promoter that directs the synthesis of the pregenome and several other transcripts with heterogeneous 5' ends is of particular interest because of its role in regulating key functions during the viral life cycle. We have examined the liver-specific characteristics of this promoter by DNA-protein interactions and by demonstrating the in vivo function of the promoter using the luciferase reporter gene expression system. The DNA-protein interactions in this region appear to be almost entirely liver-specific. Among these, a liver-specific nuclear factor, CCAAT/enhancer binding protein, binds to at least five sites on this promoter. Transient cotransfection experiments using CCAAT/enhancer binding protein expression vectors and the core promoter in the context of either the native hepatitis B virus genome or the luciferase reporter gene demonstrate that CCAAT/enhancer binding protein at low concentration modestly activates expression from the core promoter but represses at high concentration.

A study of the binding ability of pre-S1 and S2 proteins of hepatitis B virus to human serum albumin

To assess the relationship between pre-S proteins of HBV and polymerized human serum albumin (PHSA), a labeled avidin biotin ELISA was used to detect pre-S1, S2 and PHSA receptor (PHSAR) activity. PHSAR activity was only present in the samples positive for pre-S1 and/or S2, but not in the samples positive only for HBsAg. Pre-S1, S2 and PHSAR could in some degree be blocked by preincubating serum with PHSA, and the blocking efficiency of PHSA with respect to pre-S2 and PHSAR was similar, suggesting that pre-S2 is the dominant site for binding PHSA in vitro. We also found that PHSAR activity was detectable in 2 cases positive only for pre-S1, but not pre-S2. Furthermore, PHSA could selectively block pre-S1 and PHSAR activity in 2 cases negative for pre-S2, revealing that pre-S1 also possesses binding ability to PHSA, at least in a small number of cases. Using sandwich ELISA, we demonstrated the existence of complexes of HBV envelope proteins and human serum albumin (HSA) in some HBV infected serum samples. The possible significance of these complexes is discussed.

Characterization of endothelin receptors and effects of endothelin on diacylglycerol and protein kinase C in retinal capillary pericytes

Retinal capillary pericyte is a cell type selectively lost in early diabetic retinopathy. The physiological function of pericytes is not yet clearly identified, although it probably has contractile properties. We determined the specific binding of endothelin 1, a 21-amino acid peptide with potent vasoconstrictive action, and the stimulation of diacylglycerol/protein kinase C (DAG/PKC) pathway in cultured retinal capillary pericytes by endothelin. A single specific binding site for 125I-labeled endothelin was identified, with an apparent Kd of 1.3 nM and a maximal binding capacity of approximately 1-2 x 10(5) sites/cell. Endothelin (100 nM) increased total cellular DAG content by 15% at 5 min and 24% at 10 min. When pericytes were labeled isotopically with [3H]glycerol, endothelin stimulated [3H]DAG formation by 100% at 10 min and 88% at 30 min. After 10 min of endothelin treatment, PKC activities were increased by 60 and 100% in the membranous and cytosolic pools, respectively. We conclude that bovine retinal capillary pericytes possess numerous high-affinity specific binding sites for endothelin that mediate the action of endothelin by the stimulation of the DAG/PKC pathway in pericytes. These findings suggest that endothelin is a regulator of the contractile properties of pericytes, which may be adversely affected in diabetic retinopathy.

Intrahepatic expression of pre-S proteins of hepatitis B virus and its possible relation to liver cell necrosis

To assess the significance of intrahepatic expression of pre-S1 and S2 proteins of hepatitis B virus (HBV) in patients with HBV infection, an indirect immunoperoxidase technique employed monoclonal antibodies to pre-S proteins was used to detect pre-S1 and -S2 proteins in 80 liver specimens. The frequency of pre-S1 and -S2 proteins was 61.3% and 51.3%, respectively, and the co-expression of pre-S and HBsAg occurred in most specimens. The preferential expression of pre-S1 and -S2 in HBcAg-positive specimens suggests that pre-S proteins are associated with HBV replication. Membranous expression of both pre-S1 and -S2 is associated with inflammatory activity and liver cell necrosis. Furthermore, our results show that T cells, not NK or B cells, were the predominantly infiltrating cells in necrotic foci with pre-S expression. Almost all of these T cells may express HLA-DR antigen simultaneously; therefore, they are activated. In conjunction with these data, we conclude that, as the essential components of HBV envelope proteins, pre-S proteins may play an important role in resulting in liver cell necrosis.

Endothelin stimulates a sustained 1,2-diacylglycerol increase and protein kinase C activation in bovine aortic smooth muscle cells

Endothelin is a long-lasting potent vasoconstrictor peptide. We report here that in bovine aortic smooth muscle cells, endothelin biphasically increased total cellular diacylglycerol (DAG) content. When cellular DAG was labeled with [14C] glycerol for 48h, endothelin stimulated [14C]DAG formation in a biphasic pattern. Only one prolonged phase of DAG accumulation was observed when cells were labeled with [3H]glycerol for 2 h. Endothelin induced an increase in the membranous protein kinase C (PKC) activities, which lasted for more than 20 min. These data suggest that (i) endothelin stimulates a sustained generation of DAG, (ii) this accumulation of DAG results in a sustained translocation of cytosolic PKC activities to the membrane.

Expression and clinical significance of pre-S1 and S2 proteins of HBV in sera of patients with chronic liver disease

To assess the significance of pre-S proteins expression during chronic hepatitis B virus (HBV) infection, we developed a sensitive labeled avidin biotin ELISA to detect pre-S1 and pre-S2 proteins. In serum specimens from 80 patients with chronic liver disease, the frequency of pre-S1 and S2 proteins was 53.7% and 47.5%, respectively. Furthermore, it reached 87.8% and 77.6%, respectively, in cases with chronic HBV infection, indicating that pre-S proteins are usually expressed in sera with chronic HBV infection. We found that the expression of pre-S proteins is closely associated with HBV replicating markers, such as HBV DNA, HBcAg and HBeAg, in sera of patients with chronic HBV infection. Both pre-S1 and S2 proteins were often concurrently expressed in liver and serum with chronic HBV infection. However, the frequency was slightly higher in liver than in serum, suggesting that it may be clinically valuable to detect pre-S proteins in serum and liver simultaneously to determine the status of HBV infection. Our results also indicated that pre-S proteins expression in serum can serve as markers of HBV infection, but cannot be used to estimate the severity and activity of hepatic pathology.

A preliminary study on expression and significance of pre-S1 protein in liver tissue of patients with HBV infection

Rabbit antiserum to Pre-S1 protein was used to establish peroxidase-antiperoxidase (PAP) and avidin-biotin-peroxidase complex (ABC) immunohistochemical techniques for detection of Pre-S1 protein in paraffin-embedded liver tissue. Pre-S1 protein could be expressed in hepatocyte cytoplasm and on membrane in some cases with chronic viral hepatitis, cirrhosis and hepatocellular carcinoma (HCC), and its expression was intimately associated with HBsAg, HBcAg in liver and HBV DNA in serum, indicating that pre-S1 protein may represent the essential component of hepatitis B virus (HBV) and also serve as one of the markers of HBV infection. The incidence of Pre-S1 protein was slightly lower in nontumorous liver of HCC than in other cases and Pre-S1 protein could not be detected in tumorous tissue of HCC suggesting that expression of pre-S1 protein may be suppressed in HCC cases.

[An immunohistochemical study on pre-S proteins of hepatitis B virus]

An indirect immunohistochemical technique was established to detect pre-S1 and pre-S2 proteins in liver with monoclonal antibodies, and altogether 80 samples of liver were studied. Under light microscope, pre-S1 and pre-S2 were known to be expressed in a similar way and might be divided into three patterns: diffusion type, inclusion type and membrane type. Membranous type expression of both pre-S1 and pre-S2 was associated with activity of the liver diseases and liver cell necrosis. Pre-S1 and Pre-S2 were also expressed in several samples of hepatocellular carcinoma.