Evidence for Multiple Diagenetic Episodes in Ancient Fluvial-Lacustrine Sedimentary Rocks in Gale Crater, Mars.

The Curiosity rover's exploration of rocks and soils in Gale crater has provided diverse geochemical and mineralogical data sets, underscoring the complex geological history of the region. We report the crystalline, clay mineral, and amorphous phase distributions of four Gale crater rocks from an 80-m stratigraphic interval. The mineralogy of the four samples is strongly influenced by aqueous alteration processes, including variations in water chemistries, redox, pH, and temperature. Localized hydrothermal events are evidenced by gray hematite and maturation of amorphous SiO2 to opal-CT. Low-temperature diagenetic events are associated with fluctuating lake levels, evaporative events, and groundwater infiltration. Among all mudstones analyzed in Gale crater, the diversity in diagenetic processes is primarily captured by the mineralogy and X-ray amorphous chemistry of the drilled rocks. Variations indicate a transition from magnetite to hematite and an increase in matrix-associated sulfates suggesting intensifying influence from oxic, diagenetic fluids upsection. Furthermore, diagenetic fluid pathways are shown to be strongly affected by unconformities and sedimentary transitions, as evidenced by the intensity of alteration inferred from the mineralogy of sediments sampled adjacent to stratigraphic contacts.

Novel Intra-Procedural Distensibility Measurement Accurately Predicts Immediate Outcome of Pneumatic Dilatation for Idiopathic Achalasia.

OBJECTIVES: Often 2-3 graduated pneumatic dilatations (PD) are required to treat achalasia as there is no current intra-procedural predictor of clinical response. Distensibility measurements using functional lumen imaging probe (FLIP) may provide an intra-procedural predictor of outcome. Our aim was to determine the optimal criterion for esophagogastric junction (EGJ) distensibility measurements during PD that predicts immediate clinical response. METHODS: EGJ distensibility was prospectively measured using FLIP immediately pre- and post-PD. The EGJ distensibility index (EGJ-DI) was defined as a ratio of the narrowest cross-sectional area and the corresponding intra-bag pressure at 40 ml distension. Immediate and short-term clinical responses were defined as Eckardt score ≤3 assessed 2 weeks Post-PD and at 3-month follow-up, respectively. RESULTS: In 54 patients, we performed thirty-seven 30 mm; twenty 35 mm and six 40 mm PDs. The short-term response rate to the graded PD was 93% (27/29) in newly diagnosed achalasia; 87% (13/15) and 70% (7/10) in those who had relapsed after previous PD and Heller's Myotomy, respectively. Among those demonstrating an immediate response, EGJ-DI increased by an average of 4.5 mm2/mmHg (95% CI (3.5, 5.5) (P<0.001). Within-subject Δ EGJ-DI was highly predictive of immediate clinical response with AUROC of 0.89 (95% CI [0.80, 0.98], P<0.001). An increment in EGJ-DI of 1.8 mm2/mmHg after a single PD predicts an immediate response with an accuracy of 87%. CONCLUSIONS: FLIP-measured Δ EGJ-DI is a novel intra-procedural tool that accurately predicts immediate clinical response to PD in achalasia. This technique may potentially dictate an immediate mechanism to "step-up" dilator size within a single endoscopy session.

Palliation of hilar biliary obstruction from colorectal metastases by endoscopic stent insertion.

BACKGROUND: In patients with hepatic metastases from colorectal carcinoma there is a distinct subgroup in whom jaundice is not due to hepatic replacement but rather biliary obstruction. We reviewed our experience with stent insertion in patients with malignant proximal biliary obstruction from metastatic colorectal carcinoma. METHODS: Thirty-three patients were treated between July 1992 and December 1996. Placement of a single stent was attempted at initial endoscopic retrograde cholangiopancreatography. Hilar biliary obstruction was classified according to Bismuth's classification. RESULTS: Successful stent placement was possible in 94% overall and at initial endoscopic retrograde cholangiopancreatography in 39% of patients. Successful stent placement occurred significantly more often in patients with a type I stricture. Cholangitis was the principal complication occurring in 24% of patients. The 30-day mortality rate was 24%, with death occurring significantly less often in patients with a type I or II stricture. Overall, 45% of patients had a 30% fall in bilirubin at 1 week. The median survival was 81 days, with significantly longer survival seen in patients with a type I or II stricture. CONCLUSIONS: Endoscopic stent placement offers effective palliation in most patients with hilar obstruction from colorectal metastases. A subset of patients with type III strictures and greater than 3 intrahepatic metastases often do not benefit from stent insertion.

A 5-year follow-up of self-expanding metal stents in the endoscopic management of patients with benign bile duct strictures.

BACKGROUND: Metal stents offer superior biliary drainage in patients with malignant bile duct obstruction, with fewer episodes of stent occlusion compared with polyethylene stents. Metal stent patency has only been studied over limited time periods in such patients with malignant disease. OBJECTIVE: To assess the long-term patency of metal stents in a group of patients with benign bile duct strictures who are suitable for extended follow-up. METHODS: Between May 1989 and May 1992, eight patients (median age 59.0 years; range 26-88 years) with benign biliary strictures were selected at a tertiary referral centre for insertion of a metal stent. Strictures were secondary to bile duct trauma (n = 5), chronic pancreatitis (n = 2) or idiopathic (n = 1). A long metal stent was inserted in three patients and a short metal stent in five patients. RESULTS: After a median follow-up of 64.5 months (range 26-81 months, seven of the eight patients are alive. Baby scope examination at 1 year showed complete epithelialization of the metal stent in all subjects examined. Median stent patency was 35 months (range 7-72 months). Symptomatic episodes of metal stent occlusion have occurred on nine occasions in five patients (62.5%) secondary to mucosal hypertrophy (n = 3) or biliary calculi (n = 2). CONCLUSION: The long-term management of selected patients with benign bile duct strictures may be significantly improved by the use of metal stents avoiding the need for frequent polyethylene stent changes.

Leakage via aberrant bile duct due to cholangiocarcinoma.

The case of a male who had an open cholecystectomy complicated by persistent bile leak from an aberrant bile duct is presented. The persistence and volume of bile leak resulted in subsequent investigation of the biliary tree which demonstrated a cholangiocarcinoma of the right hepatic duct. This case is presented as an unusual presentation of cholangiocarcinoma and to highlight the value of modern techniques in imaging the biliary tree.

A three year follow up of self expanding metal stents in the endoscopic palliation of longterm survivors with malignant biliary obstruction.

Effective palliation of malignant biliary obstruction with conventional 10 or 12 French gauge straight polyethylene endoprostheses is limited by stent occlusion, which typically occurs four to five months after insertion. Short term follow up studies of self expanding metal stents (Wallstent, Schneider, UK) in the treatment of patients with malignant biliary obstruction have shown that their use is associated with fewer episodes of stent occlusion compared with plastic stents. There are few data, however, on the longterm patency and durability of metal stents in malignant disease. Between May 1989 and May 1992, metal stents were inserted in 28 patients with malignant bile duct strictures secondary to ampullary tumour (n = 10), pancreatic carcinoma (n = 10), cholangiocarcinoma (n = 7), and porta hepatis nodes from colorectal carcinoma (n = 1). The follow up of these patients until May 1993 is reported with a median follow up of 14.6 months. Twenty two of 28 (78.6%) patients remained free of jaundice or cholangitis. The median period of stent patency was 8.2 months (range 1.0-32.5). Thirteen patients represented with jaundice or cholangitis and endoscopic retrograde cholangiopancreatography showed evidence of stent occlusion due to tumour ingrowth. Successful clearance of metal stents was achieved by balloon trawling, or insertion of a polyethylene stent. In conclusion, metal stents provide improved longterm palliation for patients with malignant biliary strictures with fewer episodes of occlusion compared with conventional stents.

Interferon alfa for chronic active hepatitis B. Long term follow-up of 62 patients: outcomes and predictors of response.

OBJECTIVE: To evaluate the response to treatment with interferon alfa and the long term outcome of patients with chronic active hepatitis B. METHODS: Sixty-two patients with chronic active hepatitis B (43 males, 19 females; age range, 10-67 years) who were treated with interferon alfa at Westmead Hospital between 1984 and 1992 were followed up (mean period of follow-up, 44 months). Thirty-nine patients were treated with interferon alfa-2a and 23 with interferon alfa-2b for a mean of 22.5 weeks. Interferon was given three times a week with a dose range of 3-21 million U. We evaluated pretreatment predictors of response (patient's age, sex, ethnic origin, presence of cirrhosis, serum levels of alanine aminotransferase [ALT] and hepatitis B virus DNA [HBV-DNA]) and the effect of dose and type of interferon. RESULTS: Nine patients had a complete response to treatment with interferon alfa (loss of hepatitis B surface antigen), 26 had a partial response (permanently HBV-DNA negative, hepatitis B e antigen to anti-hepatitis Be seroconversion), eight had a transient response and 19 had no response. All patients with a complete response had normal ALT levels at last follow-up. Histological evidence of hepatic inflammation was significantly reduced in responders. A high pretreatment ALT level and a low HBV-DNA titre were both positive predictors of a favourable response. We found no significant difference in the response to different types of interferon or to high or low dose regimens, or in the responses of patients with cirrhosis. CONCLUSION: Treatment with interferon alfa was associated with prolonged suppression of HBV replication in over half these patients and 14% appear to have been cured of the infection. Suppression of HBV replication is associated with sustained abatement of liver disease.

Interferon suppresses erythromycin metabolism in rats and human subjects.

Interferon down-regulates expression of cytochrome P-450 3A in male rats. This study explored the hypothesis that interferon therefore decreases the metabolism of drugs catalyzed by cytochrome P-450 3A. Initial experiments in male rats used microsomal erythromycin N-demethylase activity as a probe for cytochrome P-450 3A catalytic activity. After administration of rat interferon-gamma, erythromycin metabolism was impaired (53% of control; p < 0.01). This change correlated with the decline in cytochrome P-450 3A-dependent androstenedione 6 beta-hydroxylase activity, indicating that the decrease in erythromycin N-demethylase activity could be attributed to interferon-mediated suppression of cytochrome P-450 3A. We then used the [14C]N-methyl erythromycin breath test to assess the activity of hepatic cytochrome P-450 3A in rats and human subjects before and after a single dose of interferon. In rats, rat interferon-gamma decreased erythromycin metabolism to 57% of control (p < 0.005). In the human study, six patients with chronic active hepatitis C and four healthy controls were examined 20 to 26 hr after receiving a subcutaneous injection of human interferon-alpha 2b. Interferon produced a small decrease (median = 15%; range = 3% to 35%) in erythromycin metabolism (p < 0.05), as determined by 2-hr excretion of 14CO2 in the breath. Thus interferon-mediated suppression of cytochrome P-450 3A is less strong in human subjects than in male rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon suppresses the isoform-specific activities of hepatic cytochrome P450 in female rats.

The results from the present study indicate that rat IFN-gamma decreases hepatic P450 levels and catalytic activities in female rats. The magnitude of the down-regulation of P450 is similar to that found in male rats. Furthermore, the activities of specific P450 isoforms (P4502A1 and P4502C6 and possibly P4502C12, and P4502B1 and 2) are decreased by IFN. Hence, the effect of IFN in female rats appears to involve several, but not all, hepatic P450 isoforms. Both hormone-dependent and hormone-independent isoforms are suppressed by IFN. The mechanism for this effect does not, however, appear to be mediated by changes in serum levels of sex steroids.

Can the response to interferon treatment be predicted in patients with chronic active hepatitis C?

Twenty-one of 40 patients with chronic non-A, non-B hepatitis (37 anti-HCV positive) were randomised to receive interferon alpha 2b (3 million units subcutaneously thrice weekly for 24 weeks) and then to be observed for six months. Among the other 19 patients (controls) randomised to be observed without treatment for 12 months, eight have subsequently been treated with interferon for six months. One treated patient and three controls were lost to follow-up. A return to normal serum alanine aminotransferase levels which lasted until the end of the treatment period occurred in 18 (64%) of the 28 patients given interferon (and in 13 of 21 (62%) randomised to treatment), but only in one of the 16 untreated controls (p less than 0.001). Multivariant analysis indicated that, compared with the ten nonresponders, the 18 patients who responded to interferon were more likely to have acquired infection by intravenous drug abuse than by blood transfusion (p less than 0.05), and were more likely to have histologically less severe chronic liver disease (p less than 0.01). Thus, all 13 patients with less severe liver disease histologically responded to interferon, but only five of 15 patients with cirrhosis or bridging fibrosis responded. Among 17 responders followed for more than four months, five (28%) are still in remission a median of 13 months (range four months to 24 months) after stopping interferon. The characteristics which favoured a response during treatment also appeared to distinguish those who experienced sustained post-treatment remission.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon down regulates the male-specific cytochrome P450IIIA2 in rat liver.

The aim of this study was to clarify the mechanism by which cytochrome P450 (P450)-mediated catalytic activity is decreased following interferon (IFN) administration. Microsomal steroid hydroxylation was assessed to test the hypothesis that IFN selectively decreases the activities of individual P450 isozymes in male rats. Thus, recombinant rat IFN gamma (r-rat IFN gamma) treatment produced 40% and 17% reductions in androst-4-ene-3,17-dione (androstenedione) 6 beta- and 16 beta-hydroxylation, respectively. Androstenedione 16 alpha- and 7 alpha-hydroxylation were unaltered following r-rat IFN gamma treatment. Similar changes in the androstenedione hydroxylation pathways were observed following administration of naturally derived rat IFN alpha/beta. Microsomal levels of P450IIIA2, the male-specific constitutive steroid 6 beta-hydroxylase, were lower after administration of r-rat IFN gamma (42% of control fractions). Furthermore, hepatic P450IIIA2 mRNA was found to be decreased to a similar extent by r-rat IFN gamma. These findings suggest that IFN selectively decreases the content of this isozyme by a mechanism involving altered mRNA regulation. Sex steroids were unlikely to have mediated the decrease in P450IIIA2 levels since serum estradiol and testosterone levels were unchanged by r-rat IFN gamma. In order to determine whether IFN alters the expression of P450IIIA1, a steroid-inducible member of the P450IIIA gene subfamily which is not expressed in untreated rat liver, adult female rats (which lack P450IIIA2) were coadministered pregnenolone 16 alpha-carbonitrile and r-rat IFN gamma. However, IFN failed to impair the induction of androstenedione 6 beta-hydroxylation produced by pregnenolone 16 alpha-carbonitrile. These findings suggest that although IFN decreases the expression of P450IIIA2, it may not down regulate the expression of other steroid-inducible P450IIIA proteins. In view of the existence of human P450IIIA orthologs which catalyze the metabolism of several important therapeutic agents, the findings of this study may help predict possible drug interactions in patients receiving IFN.

Randomised controlled trial of recombinant human interferon -alpha A for chronic active hepatitis B.

The efficacy of interferon treatment for Australian patients with chronic active hepatitis B (CAH-B) was assessed by a three-centre randomised controlled trial in Sydney and Brisbane. Thirty patients (29 with histologically-proven CAH-B with and without cirrhosis and one with chronic persistent hepatitis) were allocated to receive either thrice weekly intramuscular injections of recombinant human leucocyte interferon -alpha A (either 2.5, 5.0 or 10.0 million units/m2) for six months followed by 12 months of observation, or to be observed for 18 months without active treatment. Three of 23 treated patients but none of seven controls underwent clinical, biochemical and histological resolution of their disease with loss of HBsAg, HBeAg and HBV-DNA from serum. An additional six treated and two control patients underwent a sustained partial remission of their disease. This was characterised by resolution of symptoms and serum aminotransferase abnormalities in association with seroconversion from HBeAg positive to negative, loss of HBV-DNA from serum but persistent hepatitis B surface antigenaemia. In such patients, there was significant improvement in histological appearances but some necroinflammatory activity remained and fibrosis was unchanged. Although total response rates were similar in treated and control subjects, they appeared to occur earlier after interferon treatment. Treatment with interferon was associated with predictable but minor side effects that usually did not necessitate dose reduction and rarely compromised the patient's life style. Interferon is thus a feasible treatment for CAH-B. Complete responses occurred only in treated patients and partial responses appeared to occur earlier in treated than in untreated patients. However, differences in the partial response rate at 18 months were not significant and seroconversion from HBeAg positive to negative was not associated with complete histological resolution of disease activity. Hence, while interferon is a promising agent for treatment of CAH-B, efforts must continue to define more optimal treatment regimes and to identify those patients most likely to respond to this agent.

Chronic non-A, non-B hepatitis: lack of correlation between biochemical and morphological activity, and effects of immunosuppressive therapy on disease progression.

A study was made of 52 patients considered to probably have chronic non-A, non-B hepatitis who were seen during an eight-year period at Westmead Hospital, Sydney. The patients were followed for a median of 28 months to assess the natural history of the disease and, in a small number of patients, the effect of immunosuppressive therapy on disease progression was examined. In 94% of cases, infection appeared to have been acquired by a parenteral route; the remainder were sporadic infections. Fifty-six per cent of the patients had mild constitutional symptoms and the remainder were asymptomatic. Similarly, 54% of patients had no signs of chronic liver disease and none exhibited signs of hepatic decompensation. Liver biopsies were performed in 42 patients; chronic active hepatitis with or without cirrhosis was present in 90%. However, neither the presence of symptoms nor the degree of biochemical abnormality were predictive of disease severity as determined histologically. Among eight patients treated with corticosteroids (with or without azathioprine), six underwent follow-up liver biopsy. Quantitative analysis of inflammatory and fibrotic changes indicated significant (p less than 0.01) progression of histological severity during a median 33 months (range 7-98 months) between biopsies with cirrhosis developing in four instances. In contrast, among the seven untreated patients rebiopsied after a median of 16.0 months (range 11-37 months) there was no overall change in histological severity and only one patient developed cirrhosis. it is concluded that histological assessment is required in all patients suspected of having chronic non-A, non-B hepatitis as other means of assessment are unreliable.(ABSTRACT TRUNCATED AT 250 WORDS)

Rat but not human interferons suppress hepatic oxidative drug metabolism in rats.

An animal model suitable for in vivo studies of interferon-mediated suppression of hepatic oxidative drug metabolism has been developed. Rats were injected with either recombinant human interferon alpha A, recombinant human interferon gamma, recombinant rat interferon gamma, or vehicle and experiments were performed 24 h later. In some animals theophylline elimination was determined twice (10 days apart), once after interferon and once after vehicle. Theophylline clearance was also determined in the isolated perfused rat liver after pretreatment of animals with interferon or vehicle. Pretreatment of animals with rat interferon gamma significantly reduced theophylline clearance in the intact rat but neither human interferon alpha A nor human interferon gamma altered theophylline elimination in vivo. Similar results were observed in the isolated perfused rat liver. We then examined whether the effects of interferon on hepatic drug metabolism were generalized or confined to individual cytochrome P450 isozymes; androstenedione hydroxylation pathways were used as catalytic probes for individual cytochrome P450 isozymes. Rat interferon gamma (but not human interferon alpha A) decreased levels of total hepatic microsomal P450 and reduced androstenedione 16 beta-hydroxylation. The formation of three other hydroxylated androstenedione metabolites appeared reduced to a similar extent, although these changes were not significant. It is concluded that autologous but not heterologous interferons impair oxidative drug metabolism in the rat. The reduction of hepatic P450 produced by interferon may result from the suppression of multiple isozymes.

Hepatitis B in Australia: determinants of intrafamily spread.

Strategies for the control of hepatitis B virus (HBV) infection rely on information about the modes of spread and the numbers of 'at risk' individuals in particular community subgroups. This study prospectively examined 377 family and household contacts of 145 patients with HBV infection to determine the incidence of and factors determining intrafamily spread. Two hundred and forty were contacts of 68 Asian patients and 137 were contacts of 77 Caucasian patients. Serological examination of all contacts demonstrated that 161 (43%) had HBV markers including 60 (16%) who were HBsAg positive. HBV transmission within families was greater if the index case was Asian rather than Caucasian (p less than 0.001), had an HBsAg positive mother rather than an HBsAg positive father (p less than 0.01), was HBeAg positive rather than HBeAg negative (p less than 0.002), and had chronic rather than acute HBV infection (p less than 0.001). However birthplace, family size, and the activity of the liver disease of the index case did not influence HBV transmission. Within Asian families, the risk of non-sexual and non-vertical transmission of hepatitis B appeared to be as high as 18% and continued after the first three years of life. It is concluded that hepatitis B prevention programmes should include vaccination of families of chronic HBV carriers, particularly those from endemic regions such as Asia.