First-Degree Living-Related Donor Liver Transplantation in Autoimmune Liver Diseases.

Liver transplantation (LT) is the treatment of choice for end-stage autoimmune liver diseases. However, the underlying disease may recur in the graft in some 20% of cases. The aim of this study is to determine whether LT using living donor grafts from first-degree relatives results in higher rates of recurrence than grafts from more distant/unrelated donors. Two hundred sixty-three patients, who underwent a first LT in the Toronto liver transplant program between January 2000 and March 2015 for autoimmune liver diseases, and had at least 6 months of post-LT follow-up, were included in this study. Of these, 72 (27%) received a graft from a first-degree living-related donor, 56 (21%) from a distant/unrelated living donor, and 135 (51%) from a deceased donor for primary sclerosing cholangitis (PSC) (n = 138, 52%), primary biliary cholangitis (PBC) (n = 69, 26%), autoimmune hepatitis (AIH) (n = 44, 17%), and overlap syndromes (n = 12, 5%). Recurrence occurred in 52 (20%) patients. Recurrence rates for each autoimmune liver disease were not significantly different after first-degree living-related, living-unrelated, or deceased-donor LT. Similarly, time to recurrence, recurrence-related graft failure, graft survival, and patient survival were not significantly different between groups. In conclusion, first-degree living-related donor LT for PSC, PBC, or AIH is not associated with an increased risk of disease recurrence.

The chromatin remodeller ACF acts as a dimeric motor to space nucleosomes.

Evenly spaced nucleosomes directly correlate with condensed chromatin and gene silencing. The ATP-dependent chromatin assembly factor (ACF) forms such structures in vitro and is required for silencing in vivo. ACF generates and maintains nucleosome spacing by constantly moving a nucleosome towards the longer flanking DNA faster than the shorter flanking DNA. How the enzyme rapidly moves back and forth between both sides of a nucleosome to accomplish bidirectional movement is unknown. Here we show that nucleosome movement depends cooperatively on two ACF molecules, indicating that ACF functions as a dimer of ATPases. Further, the nucleotide state determines whether the dimer closely engages one or both sides of the nucleosome. Three-dimensional reconstruction by single-particle electron microscopy of the ATPase-nucleosome complex in an activated ATP state reveals a dimer architecture in which the two ATPases face each other. Our results indicate a model in which the two ATPases work in a coordinated manner, taking turns to engage either side of a nucleosome, thereby allowing processive bidirectional movement. This novel dimeric motor mechanism differs from that of dimeric motors such as kinesin and dimeric helicases that processively translocate unidirectionally and reflects the unique challenges faced by motors that move nucleosomes.

Interferon-responsive regulatory elements in the promoter of the human 2',5'-oligo(A) synthetase gene.

The interferon (IFN)-activated human 2',5'-oligo(A) synthetase E gene contains 11 RNA starts and lacks TATA and CAAT signals. DNA sequences around the promoter make the expression of the chloramphenicol acetyltransferase gene (CAT) inducible over 20-fold by IFN. A 72-base-pair segment (E-IRS) immediately upstream of the RNA starts was defined as being required for IFN-activated expression of the E-gene promoter-CAT constructs and acts in a position-independent manner. It also confers IFN-activated enhancement to the herpes simplex virus thymidine kinase promoter. On this promoter, the 5' part of the E-IRS functions as a constitutive enhancer, while the last 16 base pairs of the E-IRS is sufficient to give IFN-induced expression. On the E-gene promoter, the constitutive enhancer and the IFN-activated sequence are both needed but can be separated. In addition, promoter competition experiments indicate a third regulatory region which helps to repress expression of the E gene in uninduced cells.

Overexpression of basic fibroblast growth factor complementary DNA in Ha-ras-transformed cells correlates with a decreased incidence of tumor necrosis.

Solid tumors often contain poorly vascularized necrotic regions. In order to determine how such regions are formed within tumors and to identify substances which affect their formation, we have transformed nontumorigenic BALB/c 3T3 cells with an activated Ha-ras oncogene. Cells that were derived from independent clones of Ha-ras-transformed cells were injected s.c. into BALB/c mice. When the resulting tumors reached a weight of about 4 g, the mice received i.v. injections of 51Cr-labeled RBC. The distribution of the labeled RBC in various areas within the tumors was determined. The peripheral parts of these tumors contained viable cells, numerous blood vessels, and high concentrations of labeled RBC. The cores of the tumors on the other hand appeared necrotic, accumulated much lower concentrations of labeled RBC, and contained largely fibrous material and almost no viable cells. An expression vector containing the complementary DNA of human basic fibroblast growth factor was stably transfected into cells derived from two of the Ha-ras-transformed clones. Transfected clones of cells which produced low or intermediate amounts of basic fibroblast growth factor developed, following their injection into BALB/c mice, into tumors resembling the tumors that develop from the parental Ha-ras-transformed cells. In contrast, about one-half of the clones which produced large amounts of basic fibroblast growth factor developed into tumors which were composed almost totally of live tissue and were almost completely devoid of necrotic areas. In these tumors the labeled RBC were distributed evenly throughout the tumor.

A conformational transition at the N terminus of the prion protein features in formation of the scrapie isoform.

The scrapie prion protein (PrPSc) is formed from the cellular isoform (PrPC) by a post-translational process that involves a profound conformational change. Linear epitopes for recombinant antibody Fab fragments (Fabs) on PrPC and on the protease-resistant core of PrPSc, designated PrP 27-30, were identified using ELISA and immunoprecipitation. An epitope region at the C terminus was accessible in both PrPC and PrP 27-30; in contrast, epitopes towards the N-terminal region (residues 90 to 120) were accessible in PrPC but largely cryptic in PrP 27-30. Denaturation of PrP 27-30 exposed the epitopes of the N-terminal domain. We argue from our findings that the major conformational change underlying PrPSc formation occurs within the N-terminal segment of PrP 27-30.

Strain-specified relative conformational stability of the scrapie prion protein.

Studies of prion biology and diseases have elucidated several new concepts, but none was more heretical than the proposal that the biological properties that distinguish different prion strains are enciphered in the disease-causing prion protein (PrP(Sc)). To explore this postulate, we examined the properties of PrP(Sc) from eight prion isolates that propagate in Syrian hamster (SHa). Using resistance to protease digestion as a marker for the undenatured protein, we examined the conformational stabilities of these PrP(Sc) molecules. All eight isolates showed sigmoidal patterns of transition from native to denatured PrP(Sc) as a function of increasing guanidine hydrochloride (GdnHCl) concentration. Half-maximal denaturation occurred at a mean value of 1.48 M GdnHCl for the Sc237, HY, SHa(Me7), and MT-C5 isolates, all of which have approximately 75-d incubation periods; a concentration of 1.08 M was found for the DY strain with a approximately 170-d incubation period and approximately 1.25 M for the SHa(RML) and 139H isolates with approximately 180-d incubation periods. A mean value of 1.39 M GdnHCl for the Me7-H strain with a approximately 320-d incubation period was found. Based on these results, the eight prion strains segregated into four distinct groups. Our results support the unorthodox proposal that distinct PrP(Sc) conformers encipher the biological properties of prion strains.

Management of cardioinhibitory hypersensitive carotid sinus syncope with permanent cardiac pacing--a seventeen year prospective study.

Sudden and unannounced syncope due to increased vagal tone as manifested by hypersensitivity of the carotid sinus mechanism is not uncommon. A 17 year prospective study of 89 patients with cardio-inhibitory (Type 1) hypersensitivity showed that males outnumbered females 4.5:1. The age range at the onset of symptoms was 37 to 88 years with an average of 63 years. Hypersensitivity of the right carotid sinus was 7:1 compared to the left. These patients had unilateral hypersensitivity in 71% and bilateral in 29%. A new classification of Hypersensitive Carotid Sinus Syncope incorporating sinoatrial node (Type 1A) and atriaoventricular node (Type 1B) suppression in the Type 1 syndrome is presented. Many forms of treatment for cardioinhibitory Hypersensitive Carotid Sinus Syncope have been forthcoming but in our hands in these 89 patients over 17 years, there has been no single case of recurrence of syncope after implantation of a permanent VVI electronic cardiac pacemaker. Type 2 (vasodepressor) Hypersensitive Carotid Sinus Syncope is rare, occasionally seen combined with the cardioinhibitory (Type 1) response and it is not helped with cardiac pacing.

[Posterior approach for excision of sacral chordoma].

Chordoma is considered to be a malignant, fatal tumor. According to most authors it constitutes between 1-4% of all malignant bone tumors. In 50% of the cases it is located in the sacrum, in 35% in the cervical spine and skull, and in 15% in the thoracic spine and elsewhere. It is an aggressive, locally invasive, slowly-growing tumor. Although metastases are rare, when they occur they are of an anaplastic type, especially in the lungs, liver, regional lymph nodes, skin and muscles. Chordoma is a rare tumor, and its location and slow growth often result in delayed diagnosis. Complete excision of the chordoma was formerly considered impossible. There is often local recurrence, and often, by its very nature, excision results in neurological defects. Lately, there is more optimism regarding complete cure, due to more advanced surgical methods. We present a 66-year-old man in whom a tumor developed in the sacrococcygeal area and the right buttock. The tumor was diagnosed by CT, MRI and biopsy as a chordoma of the sacrum, without intra-abdominal infiltration. He was operated through a posterior approach, with complete resection of the tumor, including almost the whole sacrum and the coccyx. We consider this approach simpler than the abdominal-dorsal approach, which in cases of intra-abdominal infiltration is necessary. We regard this simple incision as a significant advance in the treatment of this condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatin remodelers act globally, sequence positions nucleosomes locally.

The precise placement of nucleosomes has large regulatory effects on gene expression. Recent work suggests that nucleosome placement is regulated in part by the affinity of the underlying DNA sequence for the histone octamer. Nucleosome locations are also regulated by several different ATP-dependent chromatin remodeling enzymes. This raises the question of whether DNA sequence influences the activity of chromatin remodeling enzymes. DNA sequence could most simply regulate nucleosome remodeling through its effect on nucleosome stability. In such a model, unstable nucleosomes would be remodeled faster than stable nucleosomes. It is also possible that certain DNA elements could regulate remodeling by inhibiting the interaction of nucleosomes with the remodeling enzyme. A third possibility is that DNA sequence could regulate the outcome of remodeling by influencing how reaction intermediates collapse into a particular set of stable nucleosomal positions. Here we dissect the contribution from these potential mechanisms to the activities of yeast RSC and human ACF, which are representative members of two major classes of remodeling complexes. We find that varying the histone-DNA affinity over 3 orders of magnitude has negligible effects on the rates of nucleosome remodeling and ATP hydrolysis by these two enzymes. This suggests that the rate-limiting step for nucleosome remodeling may not involve the disruption of histone-DNA contacts. We further find that a specific curved DNA element previously hypothesized to inhibit ACF activity does not inhibit substrate binding or remodeling by ACF. The element, however, does influence the distribution of nucleosome positions generated by ACF. Our data support a model in which remodeling enzymes move nucleosomes to new locations by a general sequence-independent mechanism. However, consequent to the rate-limiting remodeling step, the local DNA sequence promotes a collapse of remodeling intermediates into highly resolved positions that are dictated by thermodynamic differences between adjacent positions.

Newer interventions in myocardial infarction: do they make a difference?

Preventive aspects of coronary artery disease have made substantial advances in recent years, decreasing the incidence of coronary artery disease in Western countries. In addition to that there has been an initial drop from an in-hospital mortality of 35% to approximately 12% in the early 1960s with the establishment of coronary care units and cardiopulmonary resuscitation with defibrillation. Further to that, in recent years, it has been conclusively shown that there would be a further 20% decrease in mortality and improvement in morbidity in acute myocardial infarcts in patients treated with thrombolytic agents who present themselves within four hours of the onset of their symptoms and who are under 65 years of age. This would decrease the in-hospital mortality to approximately nine percent.

Advanced heart block during acute myocardial infarction treated with an electrode pacing catheter.

The mortality rate is high from advanced atrioventricular block associated with acute myocardial infarction. There is reason to believe that if in these patients the hearts are electrically paced with an endocardial pacing catheter, the mortality rate can be considerably decreased. Five patients in second- and third-degree heart block associated with acute myocardial infarction were paced with a considerable lowering of the expected mortality rate. Twenty-three cases from the literature are also presented and discussed. A silastic bipolar electrode catheter was used in these five cases. Four of the five cases returned to normal sinus rhythm within the first 10 days. The average duration of pacing was 6.7 days. It is the opinion of the author that second- and third-degree heart block associated with acute myocardial infarction should have a pacing catheter introduced at the earliest possible moment for continuous or demand endocardial pacing.

Permanent demand pacing for hypersensitive carotid sinus syndrome.

Ten patients with proved hypersensitivity of one or both carotid sinuses and with symptoms of recurrent lightheaded spells and syncope had implanted a permanent transvenous demand pacemaker. In a follow-up course ranging from 6 to 55 months there has been no recurrence of lightheadedness or syncope in any of the patients. Six of the ten have had their battery packs replaced owing to routine battery exhaustion.

Enhancer-like interferon responsive sequences of the human and murine (2'-5') oligoadenylate synthetase gene promoters.

The human (2'-5') oligo(A) synthetase gene contains two independent cis-acting DNA elements, A and B, which act as transcriptional enhancers. Element A alone is not activated by IFN treatment. Element B alone confers IFN-inducibility to the herpes tk promoter. Two murine (2'-5') oligo(A) synthetase genes were isolated and their promoter sequences show high conservation of element A and B. A synthetic oligonucleotide, containing 16 bp of the human element B, or 14 bp of the homologue murine element B, was linked to a TK-CAT construct. These oligonucleotides were shown to be sufficient to activate the TK promoter in the presence of IFN. When multiple repeats of the interferon-responsive sequence (E-IRS) were cloned in 5' of the TK promoter, the activation ratio was increased. In vitro, specific binding of nuclear protein(s) is observed to the radiolabelled synthetic human E-IRS. This binding is competed by the addition of cold synthetic mouse E-IRS or fragments of genomic DNA containing the E-IRS.

Pulmonary capillary hemangiomatosis.

We report a case of pulmonary capillary hemangiomatosis affecting a 35-yr-old Caucasian woman. Progressive pulmonary hypertension was documented by serial cardiac catheterizations, and pulmonary function studies showed changes suggestive of chronic pulmonary congestion. Although a difficult condition to diagnose during life as it may mimic veno-occlusive disease, capillary hemangiomatosis has a distinct histopathologic picture.

Glycosylation of vascular endothelial growth factor is not required for its mitogenic activity.

We have stably expressed the cDNA encoding the 165 amino-acid long form of human vascular endothelial growth factor (VEGF) in BHK-21 cells. VEGF was partially purified from the conditioned medium of transfected cells using heparin-sepharose affinity chromatography. The partially purified VEGF was mitogenic for various types of endothelial cells and inhibited the binding of pure [125I]VEGF to its receptors. Western blot analysis, using anti-VEGF antibodies, revealed a 47 kDa VEGF homodimer in the partially purified VEGF fraction. Preincubation of the transfected cells with the N-glycosylation inhibitor tunicamycin resulted in the conversion of the 47 kDa VEGF homodimer into a smaller, deglycosylated form of 42 kDa. Partially purified preparations of the deglycosylated VEGF displayed a mitogenic activity that was similar to that of the glycosylated form and efficiently inhibited the binding of native [125I]VEGF to the VEGF receptors of bovine aortic arch derived endothelial cells.