Exact solution of the thermodynamics and size parameters of a polymer confined to a lattice of finite size: large chain limit.

We extend the exact solutions of the Di Marzio-Rubin matrix method for the thermodynamic properties, including chain density, of a linear polymer molecule confined to walk on a lattice of finite size. Our extensions enable (a) the use of higher dimensions (explicit 2D and 3D lattices), (b) lattice boundaries of arbitrary shape, and (c) the flexibility to allow each monomer to have its own energy of attraction for each lattice site. In the case of the large chain limit, we demonstrate how periodic boundary conditions can also be employed to reduce computation time.

Influence of sternal size and inadvertent paramedian sternotomy on stability of the closure site: a clinical and mechanical study.

Background: The influence of sternal size and of inadvertent paramedian sternotomy on stability of the closure site is not well defined.

Methods: Data on 171 consecutive patients undergoing cardiac surgery through a midline sternotomy were prospectively collected. Intraoperative measurements of sternal dimension included thickness and width at the manubrium, the third and fifth intercostal spaces; paramedian sternotomy was defined as width of one side of the sternum equaling 75% or more of the entire width, at any of the three levels.

Thrombosis of the left anterior descending artery due to compression from giant pseudoaneurysm late after a bentall operation.

Background: A postoperative pseudoaneurysm may develop and gradually expand in the mediastinal space even late following Bentall operation for aortic root replacement, particularly in patients with dissection of the aorta.

Methods: A very large (148 mm) pseudoaneurysm originating of the right coronary ostium suture line was observed in a patient admitted with unstable angina 6 years after Bentall procedure for type A aortic dissection. Angiograms showed reduced flow in the right coronary and thrombotic subocclusion of the left anterior descending (LAD) coronary artery due to extrinsic compression from the expanding mediastinal mass.

Liver transplantation with vena cava in situ and selective use of temporary portacaval shunt or portal clamping.

Background/aims: The recipient hepatectomy with vena cava in situ in liver transplantation has overcome the need of venous-venous bypass thanks to temporary porta caval shunt or portal clamping.

Methodology: 150 orthotopic liver transplants in 137 patients were performed and the vena cava in situ technique was used in 142 (venous bypass in 7, temporary porta caval shunt in 49, portal clamping in 87). The suprahepatic cava veins anastomosis was performed with Belghiti in 97 and piggyback techniques in 45.

Laparoscopic surgery after orthotopic liver transplantation.

Laparoscopic surgery is currently a widely accepted approach to several surgical fields because of its advantages in terms of postoperative pain reduction and easy patient recovery. This approach may be useful even in solid-organ transplantation surgery as a diagnostic or treatment procedure in some surgical complications. From July 1991 to December 1998, we performed 142 liver transplantations on 129 patients.

Uncoupling of p21 induction and MyoD activation results in the failure of irreversible cell cycle arrest in doxorubicin-treated myocytes.

Doxorubicin (Dox, Adriamicin), a potent broad spectrum anthracycline anticancer drug, selectively inhibits muscle specific gene expression in cardiac cells in vivo and prevents terminal differentiation of skeletal muscle cells in vitro. By inducing the expression of the helix-loop-helix (HLH) transcriptional inhibitor ld2, Dox represses the myogenic function of the MyoD family of muscle regulatory factors (MRFs). In many cell types, terminal differentiation is coupled to an irreversible exit from the cell cycle and MyoD plays a critical role in the permanent cell cycle arrest of differentiating myocytes by upregulating the cyclin dependent kinase inhibitor (cdki) p21.

Configurational Entropy Approach to the Kinetics of Glasses.

A kinetic theory of glasses is developed using equilibrium theory as a foundation. After establishing basic criteria for glass formation and the capability of the equilibrium entropy theory to describe the equilibrium aspects of glass formation, a minimal model for the glass kinetics is proposed. Our kinetic model is based on a trapping description of particle motion in which escapes from deep wells provide the rate-determining steps for motion.

Mixing Plate-Like and Rod-Like Molecules With Solvent: A Test of Flory-Huggins Lattice Statistics.

Boehm and Martire have shown that the Flory-Huggins (FH) lattice model applied to mixtures of squares and rigid rods in solvent on a two dimensional lattice gives different results depending on whether rods or squares are placed first onto the lattice. This correct derivation places the validity of the FH model itself into question since the final result should be independent of the order of placement. An analysis of the FH model in terms of Poisson statistics suggests an alternative formula for the probability of successfully placing a rectangle into an area partially filled with other rectangles, which when incorporated into the FH counting procedure gives the exact thermodynamic result for the tiling of squares (i.

Modulation of intracellular signal transduction pathways by the hepatitis B virus transactivator pX.

The mechanisms by which pX, the transactivator of the hepatitis B virus (HBV), exerts its effects on transcription of viral and cellular genes and affects cell-growth regulation have not yet been fully defined. Previous reports suggested the possibility of a direct interaction of pX, which lacks intrinsic DNA-binding activity, with components of the cellular transcription machinery. More recent investigations support the hypothesis that pX might activate cellular kinases involved in transcriptional regulation and growth control.

The hepatitis B virus (HBV) pX transactivates the c-fos promoter through multiple cis-acting elements.

The hepatitis B virus (HBV) X protein (pX) stimulates transcription regulated by cis-acting elements that control many viral and cellular genes, including the c-myc and the c-fos proto-oncogenes. Using several c-fos promoter deletion mutants, we found the serum-responsive element (SRE) located at -315, the modified TPA-responsive element located at -296 (fos-AP-1 binding site, FAP) and the region spanning from nucleotide -220 to -120, which contains an NF1-like site and several stretches of sequence homologous to the AP-2 consensus binding sites, to be responsive to pX. pX does not modify the pattern of the retarded complexes bound to the SRE/FAP region which, in our system, appears to be occupied by SRE-binding factors.

Characterization of the hepatitis B virus preS/S region encoded transcriptional transactivator.

A transactivating function generated by carboxy-terminal truncation of the HBV envelope proteins has been recently described. To characterize the preS/S protein domains responsible for transactivation, preS1/S2/S and preS2/S 3' deletion mutants under the control of the adenoviral major late promoter were tested for their transactivating potential in cotransfection experiments using the c-myc and c-fos regulatory sequences as targets. Deletion of the carboxyterminal hydrophobic domain of the S protein and the presence of the endoplasmic reticulum insertion signal I (ER signal I) are required for the generation of the preS/S transactivating function.

Truncated pre-S/S proteins transactivate multiple target sequences.

In order to investigate the transactivational function of HBV truncated preS/S proteins we have constructed two sets of plasmids and have tested their transactivational potential on the c-myc regulatory sequences and the TPA-responsive element. We found that preS/S proteins only become transactivationally active when truncated at the carboxy terminal end. Furthermore, using immunofluorescence microscopy we determined that the proteins are located exclusively in the cytoplasm, apparently ruling out DNA binding and activation of factors in the nucleus.

The hepatitis B virus X protein transactivation of c-fos and c-myc proto-oncogenes is mediated by multiple transcription factors.

We have constructed two expression vectors in order to study the action of the HBV 17 Kd X protein on the c-fos and c-myc promoters. The results show that the promoters contain multiple elements that respond to X protein, suggesting involvement of multiple transcription factors. The exact mechanism of the interaction remains elusive, but our data allow speculation about the factors that may be influenced.

Recombinant immunoblot assay for hepatitis C virus antibody in chronic hepatitis.

Testing for hepatitis C virus by ELISA requires confirmation by recombinant immunoblot assay (RIBA). The first-generation RIBA uses the same antigen as used in the ELISA and one further antigen. A second-generation RIBA in which two further antigens are present, detects positivity that is not found by either the ELISA or the original RIBA.

Hepatitis B virus and hepatocellular carcinoma: a possible role for the viral transactivators.

Several epidemiological studies have demonstrated a link between chronic B virus infection and primary hepatocellular carcinoma (PHC). HBV DNA sequence integrations into the host cell genome have often been observed in hepatocarcinoma tissues. However, since only in a few cases of PHC the target of HBV-DNA insertion has been identified, alternative mechanisms for HBV-induced hepatocyte transformation have been investigated.

Full-length and truncated versions of the hepatitis B virus (HBV) X protein (pX) transactivate the cmyc protooncogene at the transcriptional level.

The products of the human hepatitis B virus (HBV) and woodchuck hepatitis B virus X genes (pXs) transactivate homologous and heterologous genes including the HBV-X and core promoters, the human immunodeficiency viruses 1 (HIV-1) and 2 (HIV-2) long terminal repeats and the beta interferon regulatory sequences. We report here that pX is also able to influence the expression of both extrachromosomal transfected c-myc regulatory sequences and endogenous c-myc gene. pX acts by increasing transcription of the c-myc gene and do not affect c-myc mRNAs stability.

Antibodies to hepatitis C virus in patients with hepatocellular carcinoma.

To study the potential relationship between the hepatitis C virus (HCV), the major etiologic agent of parenterally transmitted non-A, non-B hepatitis, and the development of hepatocellular carcinoma (HCC), we tested the presence of anti-HCV antibodies in sera from a large panel of HCC patients of different racial and geographical origins. Anti-HCV antibodies were detected in 82 out of 114 (71.9%) HBsAg-negative HCC patients and in 15 out of 53 (28.

Blood lipid abnormalities in patients suffering from peripheral vascular disease.

Blood lipid profile was investigated in 40 patients suffering from peripheral vascular disease (PVD). The most frequent abnormality was the increase of cholesterol and triglycerides. HDL-cholesterol and the subfractions HDL2 and HDL3 were decreased but not significantly.