A serine/threonine kinase gene defective in Peutz-Jeghers syndrome

Studies of hereditary cancer syndromes have contributed greatly to our understanding of molecular events involved in tumorigenesis. Here we investigate the molecular background of the Peutz-Jeghers syndrome (PJS), a rare hereditary disease in which there is predisposition to benign and malignant tumours of many organ systems. A locus for this condition was recently assigned to chromosome 19p. We have identified truncating germline mutations in a gene residing on chromosome 19p in multiple individuals affected by PJS. This previously identified but unmapped gene, LKB1, has strong homology to a cytoplasmic Xenopus serine/threonine protein kinase XEEK1, and weaker similarity to many other protein kinases. Peutz-Jeghers syndrome is therefore the first cancer-susceptibility syndrome to be identified that is due to inactivating mutations in a protein kinase.

Prevalence of BRCA1 and BRCA2 gene mutations in patients with early-onset breast cancer

BACKGROUND

Mutations in the BRCA1 and BRCA2 genes are found in most families with cases of both breast and ovarian cancer or with many cases of early-onset breast cancer. However, in an outbred population, the prevalence of BRCA1 and BRCA2 mutations in patients with breast cancer who were unselected for a family history of this disease has not been determined.

METHODS

Mutations in the BRCA1 and BRCA2 genes were detected in blood samples from two population-based series of young patients with breast cancer from Britain.

RESULTS

Mutations were detected in 15 (5.9%) of 254 women diagnosed with breast cancer before age 36 years (nine [3.5%] in BRCA1 and six [2.4%] in BRCA2) and in 15 (4.1%) of 363 women diagnosed from ages 36 through 45 years (seven [1.9%] in BRCA1 and eight [2.2%] in BRCA2). Eleven percent (six of 55) of patients with a first-degree relative who developed ovarian cancer or breast cancer by age 60 years were mutation carriers, compared with 45% (five of 11) of patients with two or more affected first- or second-degree relatives. The standardized incidence ratio for breast cancer in mothers and sisters was 365 (five observed and 1.37 expected) for 30 mutation carriers and 199 (64 observed and 32.13 expected) for 587 noncarriers. If we assume recent penetrance estimates, the respective proportions of BRCA1 and BRCA2 mutation carriers are 3.1% and 3.0%, respectively, of patients with breast cancer who are younger than age 50 years, 0.49% and 0.84% of patients with breast cancer who are age 50 years or older, and 0.11% and 0.12% of women in the general population.

CONCLUSIONS

Mutations in the BRCA1 and BRCA2 genes make approximately equal contributions to early-onset breast cancer in Britain and account for a small proportion of the familial risk of breast cancer.

Identification of the familial cylindromatosis tumour-suppressor gene

Familial cylindromatosis is an autosomal dominant genetic predisposition to multiple tumours of the skin appendages. The susceptibility gene (CYLD) has previously been localized to chromosome 16q and has the genetic attributes of a tumour-suppressor gene (recessive oncogene). Here we have identified CYLD by detecting germline mutations in 21 cylindromatosis families and somatic mutations in 1 sporadic and 5 familial cylindromas. All mutations predict truncation or absence of the encoded protein. CYLD encodes three cytoskeletal-associated-protein-glycine-conserved (CAP-GLY) domains, which are found in proteins that coordinate the attachment of organelles to microtubules. CYLD also has sequence homology to the catalytic domain of ubiquitin carboxy-terminal hydrolases (UCH).

Selective trans-splenic decompression of gastroesophageal varices by distal splenorenal shunt

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Germline mutations of the BRCA1 gene in breast and ovarian cancer families provide evidence for a genotype-phenotype correlation

Mutations in the BRCA1 gene, discovered in 1994, are associated with an 80-90% lifetime risk of breast cancer. We have analysed 60 families with a history of breast and/or ovarian cancer for germline mutations in BRCA1. Twenty-two different mutations were detected in 32 families (53%), of which 14 are previously unreported. We observed a significant correlation between the location of the mutation in the gene and the ratio of breast to ovarian cancer incidence within each family. Our data suggest a transition in risk such that mutations in the 3' third of the gene are associated with a lower proportion of ovarian cancer. Haplotype analysis supports previous data which suggest some BRCA1 mutation carriers have common ancestors; however, we have found at least two examples where recurrent mutations appear to have arisen independently.

Distal splenorenal shunt versus endoscopic sclerotherapy for long-term management of variceal bleeding. Preliminary report of a prospective, randomized trial

This paper reports the preliminary results of a prospective randomized trial comparing endoscopic variceal sclerosis and distal splenorenal shunt (DSRS) in the management of patients with cirrhosis and variceal bleeding. Seventy-one patients have been entered; 36 have received sclerosis and 35 DSRS. Randomization of the study population was stratified on Child's A/B (56%) and Child's C (44%). Sixty-one per cent had alcoholic and 39% non-alcoholic cirrhosis. No patients have been lost to follow-up, which currently stands at a median of 26 months. Rebleeding occurred significantly (p less than 0.05) more frequently in patients in the sclerosis group (19 of 36: 53%) compared to DSRS (1 of 35: 3%), but only 11 of 36 (31%) were not controlled by further sclerosis and failed that therapy. Patients in whom sclerosis failed underwent surgery. Survival was significantly (p less than 0.01) improved in the sclerosis group (+ surgery in 31%), with an 84% 2-year survival compared to a 59% 2-year survival in the DSRS group. Portal perfusion was significantly (p less than 0.05) better maintained in the sclerosis (95%) compared to the DSRS (53%) group. Galactose elimination capacity improved significantly (p less than 0.05) in 21 patients successfully managed by sclerosis at 1 year and was significantly (p less than 0.01) better maintained in the sclerosis compared to DSRS group. The authors conclude that endoscopic sclerosis: has a higher rebleeding rate than DSRS, with one third of patients failing therapy from rebleeding; allows significant improvement in liver function when successful; and gives significantly improved survival in the management of variceal bleeding when backed up by surgical therapy for patients with uncontrolled rebleeding.

Mutagenicity of carcinogenic methylating agents is associated with a specific DNA modification

The carcinogenic potency of simple aliphatic alkylating agents such as the alkylnitrosamides and the alkylmethanesulphonates is positively correlated with their ability to alkylate the relatively weakly nucleophilic oxygen atoms in DNA, particularly the O6-atom of guanine. Differences in the spectrum of DNA alkylations produced by these agents can be rationalised on chemical grounds in that the electrophilic reactivity of the alkylating species determines the extent to which it will react at sites of weaker nucleophilicity. Alkylation of the more strongly nucleophilic ring nitrogen atoms of the purine bases, which is the main site of reaction with all these agents, appears to be much less important in alkylation carcinogenesis. O6-alkylation of guanine is likely to interfere with DNA base-pair hydrogen bonding and is possibly the major DNA modification responsible for the induction of GC yields AT transition mutations in bacteria and bacteriophage by alkylating agents. Here, we have studied the effects of three methylating agents of contrasting carcinogenic potency on mammalian (V79 Chinese hamster) cells in in culture. We report that the mutagenicity but not the cytotoxicity of each agent reflects its carcinogenicity and, furthermore, that the marked differences in mutagenicity are closely paralleled by differences in levels of O6-guanine methylation.

Alkylation of deoxyribonucleic acid in vivo in various organs of C57BL mice by the carcinogens N-methyl-N-nitrosourea, N-ethyl-N-nitrosourea and ethyl methanesulphonate in relation to induction of thymic lymphoma. Some applications of high-pressure liquid chromatography

1. Methods were developed for analysis of alkylpurines, O2-alkylcytosines, and representative phosphotriesters [alkyl derivatives of thymidylyl(3'-5')thymidine], in DNA alkylated in vivo, using high-pressure liquid chromatography. 2. The patterns of alkylation products in DNA in vivo at short times were closely similar to those found for reactions in vitro. Alkylation by the nitrosoureas was complete in vivo within 1 h, but with ethyl methanesulphonate was maximal at 2--4h. 3. The time course of persistence of alkylation products in vivo was determined for several tissues. In addition to the rapid loss of 3- and 7-alkyladenines reported previously for all tissues, a relatively rapid loss of O6-alkylguanines from DNA of liver was found which was more rapid at lower doses. In brain, lung and kidney, excision of O6-alkylguanine was much less marked, but was not entirely excluded by the data. In thymus, bone marrow and small bowel, all alkylated bases were lost with half-lives of 12--24h, at non-cytotoxic doses of alkylation. 4. No evidence for any marked excision of other minor products from alkylated DNA in vivo was found; thus 1-methyladenine, O2-ethylcytosine (found in appreciable amount only with N-ethyl-N-nitrosourea), 3-methylguanine, and dTp(Alk)dT persisted in alkylated DNA, including DNA of liver. 5. The induction of thymic lymphoma was determined over the range of single doses by intraperitoneal injection up to about 60% of the LD50 values, and related to the extent of alkylation of target tissues thymus and bone marrow. With N-methyl-N-nitrosourea over 90% tumour yield was attained at 60 mg/kg, and with N-ethyl-N-nitrosourea up to 52% at 240 mg/kg, but with ethyl methanesulphonate at up to 400 mg/kg only a few per cent of tumours were obtained. 6. The carcinogenic effectiveness of the agents was positively correlated with the extents of alkylation of guanine in DNA of target tissues at the O-6 atom. On the basis that at doses giving equal carcinogenic response these extents of alkylation would be equal, the chemical analyses showed that the ratio of equipotent doses to that for N-methyl-N-nitrosourea would be, for N-ethyl-N-nitrosourea, 5.3 for ethyl methanesulphonate about 21, and for methyl methanesulphonate [Frei & Lawley (1976) Chem.-Biol. Interact. 13, 215--222] about 144. These predictions were in reasonably good agreement with the observed dose-response data for these agents.

A randomized, controlled trial of the distal splenorenal shunt

In 1971 a prospective, randomized trial was initiated to determine efficacy of the distal splenorenal shunt in the management of cirrhotic patients who had previously bled from esophageal varices. When entry into the trial was terminated in 1976, 26 patients had received the distal splenorenal shunt (selective) and 29 had undergone a nonselective shunting procedure (18 interposition mesorenal, six interposition mesocaval, and five other nonselective shunts). Three operative deaths occurred in each group. Early postoperative angiography revealed preservation of hepatic portal perfusion in 14 of 16 selective patients (88%), but in only one of 20 nonselective patients (5%; p < .001). Quantitative measures of hepatic function (maximal rate of urea synthesis or MRUS and Child's score) were similar to preoperative values in the selective group but were significantly decreased in nonselective patients on the first postoperative evaluation (p < .001 for MRUS; p < .05 for Child's score). Eighty-seven per cent of selective and 81% of nonselective patients have now been followed for three to six years since surgery. Late postoperative evaluation of 29 survivors (12 selective, 17 nonselective) still shows an advantage to the selective group with respect to MRUS, Child's score, and incidence of hepatopetal portal blood flow, but differences are no longer statistically significant. However, if the seven patients with portal flow (five selective; two nonselective) are compared to the 20 with absent portal flow (seven selective; 13 nonselective), the former group has significantly higher values for MRUS (p < .05) and Child's score (p < .025). No patient with continuing portal perfusion has developed encephalopathy as compared to a 45% incidence of this complication in individuals without portal flow (p < .05). No significant differences between selective and nonselective groups have appeared with respect to total cumulative mortality (ten selective; 38%; eight nonselective, 28%), shunt occlusion (two selective, 10%; five nonselective, 18%), or recurrent variceal hemorrhage (one selective, 4%; two nonselective, 8%). Overall, significantly fewer selective patients have developed postoperative encephalopathy (three selective, 12%; 15 nonselective, 52%; p < .001). Therefore, we conclude that the distal splenorenal shunt, especially when its objective of maintaining hepatic portal perfusion is achieved, results in significantly less morbidity than nonselective shunting procedures.

Ten years portal hypertensive surgery at Emory. Results and new perspectives

Five hundred four Shunt procedures have been done at Emory University Hospitals between 1971 and 1981 to decompress bleeding esophageal varices. This paper reviews how far the experiences of a prospective randomized study (55 patients) of distal splenorenal shunts against total shunts is supported by the nonrandomized experience (449 patients), and outlines our current methods of management dictated by this experience. The overall operative mortality for 348 selective shunts is 4.1% and for 156 nonselective shunts, 14.1%. The five-year survival following Selective shunt is 59%, and following nonselective shunt is 49%: more than half the selective shunt patients are alive, in contrast to the median survival of 44.5 months for patients having nonselective shunts. Following Selective shunt, the survival in nonalcoholic patients is significantly better than the median survival of alcoholic patients of 57 months. Encephalopathy, reported at three years after surgery in the randomized patients was significantly (p < 0.001) lower after selective shunt (12%) compared to nonselective shunt (52%): in the same population at seven years, all patients with patent nonselective shunts have clinical or subclinical encephalopathy, but only 30% of the selective shunt patients have subclinical encephalopathy. Shunt patency, immediately after surgery, is 93% following selective shunt, with only two documented late thromboses: nine of nine patients, at a mean of seven years, retain patency in the randomized study. Shunt occlusion increases with time after interposition nonselective shunts: seven of 13 are occluded at a mean follow-up of seven years in the randomized study. Portal venous perfusion is retained in 93% of patients seven to ten days after selective shunt, but in no patient with a patent nonselective shunt. Late portal perfusion is maintained in nine of the eleven patients in the randomized group studied at a mean of seven years after selective shunt. Restoration of portal perfusion has led to clearing of encephalopathy and improvement in hepatic function in six patients. The following conclusions are made: (1) selective shunts can be done with low operative mortality, and long-term patency with excellent control of bleeding; (2) hepatic portal venous perfusion has been maintained after selective shunt for ten years, and this is vital for preventing encephalopathy and maintaining hepatic function; (3) long-term survival after selective shunt is better than any reported series for nonselective shunt; and (4) selective shunts are the operative procedure of choice for variceal decompression and nonselective shunts should rarely be performed for elective decompression.

The Emory prospective randomized trial: selective versus nonselective shunt to control variceal bleeding. Ten year follow-up

From 1971 to 1975, 55 patients with variceal bleeding secondary to cirrhosis were entered into a prospective randomized trial comparing distal splenorenal (selective) and H-graft interposition (nonselective) shunt. This 10-year follow-up documents that selective shunt is better (p less than 0.05) in four of the five variables monitored. Control of bleeding: selective shunt prevented variceal bleeding better than interposition shunt due to the higher (0.05 less than p less than 0.1) occlusion rate (30%) of interposition shunt. Selective shunt maintained postoperative portal perfusion better (p less than 0.01) than patent interposition shunt. Seventy-five per cent of selective shunt survivors have portal perfusion at 10 years: no patient with a patent nonselective shunt perfuses the liver. Quantitative liver function was better preserved (p less than 0.01) 10 years after selective shunt than nonselective shunt. Postoperative encephalopathy occurred in fewer (p less than 0.01) selective (27%) than nonselective (75%) shunt patients over the 10 years. Survival: in the randomized population, the improved survival in the selective shunt subgroup did not reach statistical significance. However, improved survival was confirmed in nonalcoholics. Five of eight nonalcoholics operated with selective shunt are alive at 10 years with patent shunts. No nonalcoholic, of seven total, operated with nonselective shunt survived 10 years with a patent shunt. These data show that selective shunt was superior to nonselective shunt. There was less rebleeding and encephalopathy after distal splenorenal shunt; postoperative portal perfusion and hepatic function were maintained.

Maximal rates of excretion and synthesis of urea in normal and cirrhotic subjects

When normal individuals eat 0.33 g protein N/kg body weight (BW)((3/4)) per day, they excrete 10-15 mg urea N/h per kg BW((3/4)). If they now ingest (at 0 h) 0.27 (dose A), 0.40 (dose B), 0.53 (dose C), 0.94 (dose D), or 1.33 (dose E) g protein N/kg BW((3/4)) (in the form of casein, ovalbumin, or lactalbumin), the rate of urea N excretion accelerates within 4 h. At dose C a maximal rate of urinary urea N excretion (MRUE) is reached, which averages 55 mg urea N/h per kg BW((3/4)) and which persists for 16 h. Higher doses of protein do not further accelerate urea excretion, but prolong the duration of MRUE to 28 h (after dose E). Blood urea N (BUN) rises by 7-20 mg/100 ml during the first 8 h after dose C to E, and remains stable within +/-5 mg/100 ml during the ensuing 8-28 h of MRUE. Each increment of protein above dose C causes a further increment in plasma alpha-amino N. During infusion of free amino acids at a rate of 110 or 165 mg amino acid N/h per kg BW((3/4)) for 12 h, rate of urea excretion increases to the MRUE value produced by dose C-E of oral protein.These findings indicate that MRUE corresponds to a period of maximal rate of urea synthesis (MRUS). MRUS is greater than MRUE because one fraction of newly formed urea is hydrolyzed in the gastrointestinal tract, and another fraction may accumulate temporarily in body water during the MRUE period. Oral neomycin reduces the proportion of urea hydrolyzed in the gut to less than 20%; its extent is measured by recovery in the urine of a tracer dose of [(14)C]urea injected intramuscularly during determination of MRUE. Accumulation of urea in body water is estimated from increment in BUN during the period of MRUE measurement (8-24 h after dose E of casein) and from body water measured with (3)H(2)O. Then MRUS is calculated as: ([mg urea N excreted between 8 and 24 h after dose E] + [BUN at 24 h - BUN at 8 h] x [body water]) x (100/% recovery [(14)C]urea) x (1/kg BW((3/4))) x (1/16 h).MRUS in 10 normal subjects averaged 65 mg urea N/h per kg BW((3/4)) (range 55-76), and in 34 cirrhotics 27 mg urea N/h per kg BW((3/4)) (range 6-64). Among 19 cirrhotic patients fed 40, 60, 80, or 100 g protein daily for successive 10 day periods, the occurrences of hyperammonemia, hyperaminoacidemia, and encephalopathy at each level of protein intake were inversely related to MRUS value.

Asymmetric methylation in the hypermethylated CpG promoter region of the human L1 retrotransposon

We have investigated the function and sequence specificity of DNA methylation in the hypermethylated CpG island promoter region of the endogenous human LINE-1 (L1) retrotransposon family. In nontransformed human embryonic fibroblasts, inhibition of DNA methylation with 5-azadeoxycytidine induced a greater than 4-fold increase in transcription from potentially functional L1 elements without increasing the transcription level of the majority of degenerate elements, implicating hypermethylation in the repression of L1 activity. Using bisulfite genomic sequencing to assess the pattern of methylation in a subset of nondegenerate L1 elements, we found 29 sites within a 460-base pair region of the noncoding (top) DNA strand of the L1 promoter in which cytosine methylation was maintained with high efficiency. Of these, 25 were at CG dinucleotides and four were in non-CG sites. When the methylation sites were analyzed for the complementary (bottom) strand, the only highly conserved sites of methylation were in CG dinucleotides. Several of these sites of CG methylation in the bottom (coding) strand were at positions where top (noncoding) strand-derived sequences were unmethylated, suggesting that these sites might be maintained in a hemi-methylated state. Hence, there is a subset of human L1 elements in which methylation is efficiently maintained in asymmetric non-CG sites and further that this non-CG methylation may be part of a wider phenomenon involving hemi-methylation at CG dinucleotides. Maintenance of asymmetric methylation at non-CG sites (and possibly at hemi-methylated CG dinucleotides) could be through a novel DNA methyltransferase activity. Alternatively, the promoter region of L1 elements may be induced by factor binding to form some type of secondary structure that presents as a highly efficient substrate for de novo methylation.

The Hermes transposable element from the house fly, Musca domestica, is a short inverted repeat-type element of the hobo, Ac, and Tam3 (hAT) element family

The genome of the house fly, Musca domestica, contains an active transposable element system, called Hermes. Using PCR and inverse PCR we amplified and sequenced overlapping segments of several Hermes elements and from these data we have constructed a 2749 bp consensus Hermes DNA sequence. Hermes termini are composed of 17 bp imperfect inverted repeats that are almost identical to the inverted terminal repeats of the hobo element of Drosophila melanogaster. Full length Hermes elements contain a single long ORF capable of encoding a protein of 612 amino acids which is 55% identical to the amino acid sequence of the hobo transposase. Comparison of the ends of the Hermes and hobo elements to those of the Ac element of Zea mays, and the Tam3 element of Antirrhinum majus, as well as several other plant and insect elements, revealed a conserved terminal sequence motif. Thus Hermes is clearly a member of the hobo, Ac and Tam3 (hAT) transposable element family, other members of which include the Tag1 element from Arabidopsis thaliana and the Bg element from Zea mays. The evolution of this class of transposable elements and the potential utility of Hermes as a genetic tool in M. domestica and related species are discussed.

A hypercoagulable state follows orthotopic liver transplantation

Orthotopic liver transplantation may be associated during the postoperative period with hepatic artery thrombosis, a catastrophic occurrence generally necessitating emergency retransplantation. To assess the contribution of the coagulation mechanism to this complication, the levels of procoagulant and anticoagulant proteins were followed in 41 liver transplant patients during the first 10 postoperative days. The mean activities of all procoagulant factors reach normal values on day 1 except for factors V and VII, which achieve normal activity by day 3. Supernormal levels of factor VIII activity and antigen are noted (peak values on day 5 of 334% +/- 113% and 481% +/- 260%, respectively). The anticoagulant proteins show delayed recovery, with deficient antithrombin III levels seen in 81% of patients on day 3 and 57% on day 5. Similarly, proteins C and S are subnormal in 24% and 21%, respectively on day 3, and 20% and 10%, respectively, on day 5. During this period, elevated levels of thrombin/antithrombin complexes are encountered, reflecting in vivo activation of the coagulation mechanism. Activated thrombin is, therefore, being generated at a time when a decrease in the major regulatory anticoagulant proteins exists. These data suggest an imbalance between the hemostatic and thrombotic mechanisms and indicate a sustained prothrombotic state that may contribute to the risk for hepatic artery thrombosis. Using a regimen of low-dose heparin and fresh frozen plasma infusion, no thromboses have been seen in 65 consecutive liver transplants.

The hobo transposable element of Drosophila can be cross-mobilized in houseflies and excises like the Ac element of maize

The hobo transposable element from Drosophila melanogaster was found to be capable of excision, resulting in donor sites unlike those reported for any other transposable element currently known in animals. These empty sites most closely resemble those left by the transposable elements Ac and Tam3 in Zea mays and Antirrhinum majus, respectively. Like Ac and Tam3, the hobo element was found to function in a distantly related species, in this case the housefly Musca domestica. Hobo excision in M. domestica was found not to require the expression of hobo-encoded transposase but instead appears to be driven by an endogenous hobo transposase-like activity. DNA sequences displaying high homology to the hobo transposase gene were isolated from the genome of M. domestica and appear to be part of a mobile-element system related to hobo, Ac, and Tam3.

The Drosophila RAD21 cohesin persists at the centromere region in mitosis

'Cohesin' is a highly conserved multiprotein complex thought to be the primary effector of sister-chromatid cohesion in all eukaryotes. Cohesin complexes in budding yeast hold sister chromatids together from S phase until anaphase, but in metazoans, cohesin proteins dissociate from chromosomes and redistribute into the whole cell volume during prophase, well before sister chromatids separate (reviewed in [1,2]). Here we address this apparent anomaly by investigating the cell-cycle dynamics of DRAD21, the Drosophila orthologue of the Xenopus XRAD21 and Saccharomyces cerevisiae Scc1p/Mcd1p cohesins [3]. Analysis of DRAD21 in S2 Drosophila tissue culture cells and live embryos expressing a DRAD21-green fluorescent protein (GFP) fusion revealed the presence of four distinct subcellular pools of DRAD21: a cytoplasmic pool; a chromosome-associated pool which dissociates from chromatin as chromosomes condense in prophase; a short-lived centrosome-associated pool present during metaphase-anaphase; and a centromere-proximal pool which remains bound to condensed chromosomes, is found along the junction of sister chromatids between kinetochores, and persists until the metaphase-anaphase transition. We conclude that in Drosophila, and possibly all metazoans, a minor pool of cohesin remains bound to centromere-proximal chromatin after prophase and maintains sister-chromatid cohesion until the metaphase-anaphase transition.

Endoscopic variceal sclerosis compared with distal splenorenal shunt to prevent recurrent variceal bleeding in cirrhosis. A prospective, randomized trial

STUDY OBJECTIVE

To define the roles of endoscopic variceal sclerosis and distal splenorenal shunt in the prevention of recurrent variceal bleeding in patients with cirrhosis.

DESIGN

A prospective, randomized clinical trial with crossover for those failing therapy. The median follow-up was 61 months.

SETTING

A private, tertiary-referral university hospital.

PATIENTS

Seventy-two patients fulfilling inclusion criteria were drawn from a total of 420 patients treated during a 4.5-year interval.

TREATMENTS

Endoscopic variceal sclerosis or distal splenorenal shunt.

MEASUREMENTS AND MAIN RESULTS

Survival was significantly (P = 0.02) improved in patients randomly assigned to receive sclerotherapy: 13 of these 37 (35%) patients failed sclerotherapy and required surgical rescue. A survival advantage (P = 0.01) was seen in patients with alcoholic cirrhosis who had this combined therapy; however, in patients with nonalcoholic cirrhosis, survival for those receiving sclerotherapy and surgical rescue was not significantly (P = 0.36) different from that of patients receiving distal splenorenal shunt. Control of variceal bleeding was significantly (P less than 0.001) better in the distal splenorenal shunt group (34 of 35 [97%] compared with 15 of 37 [41%] in the sclerotherapy group). Using death, uncontrolled rebleeding, or shunt thrombosis as the endpoints resulted in no significant difference between treatment groups. Hepatocyte function and portal perfusion were significantly better maintained in patients with alcoholic cirrhosis who were managed by sclerotherapy rather than shunt (P = 0.01 and P = 0.001, respectively).

CONCLUSIONS

Endoscopic sclerotherapy with surgical rescue for uncontrolled bleeding is the optimum therapy for patients with alcoholic cirrhosis and variceal bleeding. Survival is similar in nonalcoholic patients treated with either distal splenorenal shunt or endoscopic sclerotherapy, but shunting provides better control of variceal bleeding.

Mutations in the p53 gene in schistosomal bladder cancer: a study of 92 tumours from Egyptian patients and a comparison between mutational spectra from schistosomal and non-schistosomal urothelial tumours

Much of bladder cancer in East Africa and the Middle East is attributed to chronic urinary infection with Schistosoma haematobium ('schistosomiasis'). Most schistosomal bladder cancer (SBC) is squamous cell carcinoma (SCC) and occurs in the fifth decade of life. In contrast, nonschistosomal bladder cancer (NSBC) in Western countries usually occurs in the seventh decade of life and is largely transitional cell carcinoma (TCC). To shed light on the mechanisms underlying these different patterns of bladder cancer we looked for mutations in the p53 gene in SBC from 92 patients in Egypt, where schistosomiasis is hyperendemic. Patients' mean age at presentation of bladder cancer was 49.4 +/- 9.9 years and 90% had a clinical history of schistosomiasis and/or histological evidence of schistosomal eggs adjacent to the carcinoma. There were 53 SCC, 23 TCC, 13 adenocarcinomas and three other carcinomas. Thirty patients had tumours with mutations in exons 5-8 of the p53 gene: 17/53 SCC, 8/23 TCC, 4/13 adenocarcinomas and 1/3 other tumours. Of 19 mutations in SCC, 16 were base pair substitutions (BPS), two were deletions and one an insertion. Two tumours each contained two mutations. Of the BPS, nine were transitions at CpG dinucleotides and two were G-->T transversions. All the mutations in TCC were BPS: four were transitions at CpG dinucleotides and three were G-->C transversions. One TCC had two mutations. Of four adenocarcinomas with mutations, two had transitions at CpG dinucleotides. Of the 30 BPS mutations, 16 were transitions at CpG dinucleotides, of which 12 were C-->T. We combined these 33 mutations with six obtained from Egyptian SCC reported by Habuchi et al. (Cancer Res., 53, 3795-3799, 1993) to compile a mutational spectrum. This was compared with a NSBC spectrum assembled from 118 mutations reported in the literature. The proportion of BPS at CpG dinucleotides was significantly higher in SBC than in NSBC (18/34 versus 25/103, P = 0.003). There was also a bias away from mutations in exons 7 and 8 towards mutations in exons 5 and 6. We suggest that the excess of transitions at CpG dinucleotides in SBC results from nitric oxide (NO) produced by the inflammatory response provoked by schistosomal eggs. NO could produce such mutations directly, by deamination of 5-methylcytosine, and indirectly, following conversion to nitrate, bacterial reduction to nitrite and endogenous formation of urinary N-nitroso compounds. These produce O6-alkylguanines in DNA, leading to very high rates of G:C-->A:T transitions, a process possibly augmented by inefficient repair of alkylated bases at CpG dinucleotides.

Hermes, a functional non-Drosophilid insect gene vector from Musca domestica

Hermes is a short inverted repeat-type transposable element from the house fly, Musca domestica. Using an extra-chromosomal transpositional recombination assay, we show that Hermes elements can accurately transpose in M. domestica embryos. To test the ability of Hermes to function in species distantly related to M. domestica we used a nonautonomous Hermes element containing the Drosophila melanogaster while (w+) gene and created D. melanogaster germline transformants. Transgenic G1 insects were recovered from 34.6% of the fertile G0 adults developing from microinjected w- embryos. This transformation rate is comparable with that observed using P or hobo vectors in D. melanogaster, however, many instances of multiple-element insertions and large clusters were observed. Genetic mapping, Southern blotting, polytene chromosome in situ hybridization and DNA sequence analyses confirmed that Hermes elements were chromosomally integrated in transgenic insects. Our data demonstrate that Hermes elements transpose at high rates in D. melanogaster and may be an effective gene vector and gene-tagging agent in this species and distantly related species of medical and agricultural importance.

Hemodynamic differences between alcoholic and nonalcoholic cirrhotics following distal splenorenal shunt--effect on survival?

The distal splenorenal shunt significantly improves 5-year survival from variceal bleeding in nonalcoholic (70%) compared to alcoholic (45%) cirrhosis patients. This study quantitates hemodynamic differences occurring in the first year after DSRS in 16 alcoholic compared to eight nonalcoholic patients. Portal venous perfusion was retained significantly better (p less than .01) by the nonalcoholic (seven of eight) than by the alcoholic (four of sixteen) patients. Mean liver blood flow (p less than 0.07), flow/unit liver volume (p less than .05), and flow required to perform a specific hepatocyte function (p less than 0.05) all increased significantly in the alcoholic compared to nonalcoholic group. Cardiac output increased significantly in the alcoholic patients (p less than 0.05), but was unchanged in the nonalcoholic patients. The alcoholic patients divided into two subsets, 11 who showed increase in flow (1082 +/- 260 to 1496 +/- 388 ml/min) and five who did not (1246 +/- 269 to 994 +/- 159 ml/min). The former had significantly (p less than 0.05) poorer hepatocyte function and had a significant (p less than 0.05) increase in flow/unit volume and flow/unit function at 1 year, which may have helped to maintain hepatocyte integrity. The latter, in parallel with the nonalcoholic patients, showed no significant change in these parameters and maintained a good functional hepatocyte mass. These data lead us to hypothesize that: 1) alcoholic liver injury has an increased risk of leading to loss of portal perfusion after DSRS, 2) as hepatocyte function falls, there is initial increase in hepatic arterial flow in alcoholic patients, triggered by increase in cardiac output, and 3) progressive injury and/or failure of the compensatory hemodynamic mechanism leads to earlier mortality in alcoholic patients. In contrast, the nonalcoholic cirrhosis patients preserve portal perfusion and maintain liver blood flow, both quantitatively and qualitatively, with retained hepatocyte function and improved survival.

Selective and total shunts in the treatment of bleeding varices. A randomized controlled trial

Two types of surgical therapy of bleeding esophageal varices were evaluated in 48 patients by a randomized controlled trial: 24 were randomized for a total shunt and 24 for the selective shunt. In two of the latter, a total shunt had to be performed for technical reasons. The fatality rates (six in the 24 total, and six in 22 selective [performed], and seven in 24 selective [randomized]), the frequency of shunt occlusion (two in each group), and of recurrent gastronintestinal bleeding (three in each group) were similar. Encephalopathy developed more often after a total shunt -- 10 of 24, or one per 58 patient-months -- than after selective (performed) -- one of 22, or one per 593 patient-months (P less than 0.005). Total shunts consistently diverted the hepatopetal mesenteric-portal flow from the liver. Deterioration of hepatic function (maximum rate of urea synthesis) was greater after total than selective shunt (P less than 0.05).

The t(8;13)(p11;q11-12) rearrangement associated with an atypical myeloproliferative disorder fuses the fibroblast growth factor receptor 1 gene to a novel gene RAMP

A recently described atypical myeloproliferative disorder is invariably associated with reciprocal translocations involving 8p11-12. The most common rearrangement is a t(8;13)(p11;q11-12). Here we determine that this translocation results in the fusion of the fibroblast growth factor receptor 1 gene (FGFR1), a member of the receptor tyrosine kinase family at 8p11, to a novel gene at 13q11-12 designated RAMP . The predicted RAMP protein exhibits strong homology to the product of a recently cloned candidate gene for X-linked mental retardation, DXS6673E . We also provide the first report of a novel, putative metal-binding motif, present as five tandem repeats in both RAMP and DXS6673E. RT-PCR detected only one of the two possible fusion transcripts, encoding a product in which the N-terminal 641 amino acids of RAMP become joined to the tyrosine kinase domain of FGFR1. Receptor tyrosine kinases are not commonly involved in the formation of tumour-specific fusion proteins. However, the previous reports of involvement of receptor tyrosine kinases in fusion proteins in non-Hodgkin's lymphoma, chronic myelomonocytic leukaemia and papillary thyroid carcinoma described similar rearrangements. By analogy with these, we propose that the RAMP-FGFR1 fusion product will contribute to progression of this myeloproliferative disorder by constitutive activation of tyrosine kinase function.