Perioperative mortality in liver transplantation before and after the implementation of the organ allocation policy Share 35.

INTRODUCTION: In 2013, a new liver transplant allocation policy (Share 35) aimed to reduce waitlist-mortality was introduced in the United States. Regional organ sharing for recipients with a MELD score of ≥35 was prioritized over local allocation to those with lower MELD scores. Our aim was to assess the changes in perioperative mortality following the introduction of Share 35 as well as changes in patients' short-term 7-day survival, patients discharged alive and 1-year survival. Analyses were also carried out for the subgroups of patients with MELD scores ≥ and < 35. METHODS: We used data from the Scientific Registry of Transplant Recipients and included liver transplants between March 2002 and December 2018 in this retrospective cohort study. Perioperative mortality was defined as death during and within two days of liver transplant. We used robust interrupted time series analyses to evaluate the impact of Share 35 on mortality. RESULTS: We included 90 002 liver transplants in our analysis and observed a decreasing trend in perioperative mortality over time (-.061 deaths per 1000 cases per month, 95% CI -.084 to -.037, p < .001). Share 35 was not associated with a change in perioperative mortality (p = .33), short-term 7-day survival (p = .48), survival to discharge (p = .56), or 1-year survival (p = .27). CONCLUSIONS: Prioritizing sicker recipients with a MELD score ≥35 for liver transplantation was not associated with a change in postoperative mortality.

Internal Hydrogen Bond Formation in a syn-Hydroxyepoxide.

The existence of an internal hydrogen bond in a compound representative of a syn diol epoxide (a possible intermediate in chemical carcinogenesis by certain polycyclic aromatic hydrocarbons) has been demonstrated by x-ray crystallographic and nuclear magnetic resonance studies. This internal hydrogen bond was found in 3,4-epoxy-2-methyl-1,2,3,4-tetrahydro-1-naphthol and was shown to persist in dioxane-water solutions containing up to 80 mole percent water. In this structure, the 1-hydroxy and 2-methyl groups are shown to occupy axial positions. In the anti diol epoxide, which has no internal hydrogen bond, analogous groups are equatorial. Crystals of the compound were unstable in the x-ray beam while the data were being collected (even at low temperatures), presumably as a result of decomposition.

Fas preassociation required for apoptosis signaling and dominant inhibition by pathogenic mutations.

Heterozygous mutations encoding abnormal forms of the death receptor Fas dominantly interfere with Fas-induced lymphocyte apoptosis in human autoimmune lymphoproliferative syndrome. This effect, rather than depending on ligand-induced receptor oligomerization, was found to stem from ligand- independent interaction of wild-type and mutant Fas receptors through a specific region in the extracellular domain. Preassociated Fas complexes were found in living cells by means of fluorescence resonance energy transfer between variants of green fluorescent protein. These results show that formation of preassociated receptor complexes is necessary for Fas signaling and dominant interference in human disease.

In vivo evaluation and in vitro metabolism of leuprolide in mice--mass spectrometry-based biomarker measurement for efficacy and toxicity.

The study of pharmacologically active peptides is central for the understanding of cancer and the development of novel therapeutic approaches. In this context, both qualitative and quantitative determination of bioactive peptides in biological fluids/tissues and their effect on endogenous factors (e.g. hormones) are of great importance. A mass spectrometry-based approach was developed and applied towards the measurement of leuprolide, a peptide drug for the treatment of prostate cancer, in mouse plasma. High-pressure liquid chromatography coupled to a hybrid quadrupole linear ion trap (QqLIT) mass spectrometer, a platform that combines the benefits of triple QqLIT instruments, was employed for the study. Using the described methodology, we established that picomolar concentrations of leuprolide could be measured in mouse plasma (limit of quantification of 0.1 ng/ml). In order to optimize pharmacokinetic properties of analogs of leuprolide, a facile in vivo mouse model was developed and leuprolide concentrations were determined in mouse plasma following intraperitoneal administration. In the same animal model, we demonstrated the versatility of the described MS-based approach by the determination of plasma concentrations of testosterone, an established biomarker for the treatment of prostate cancer. Following dosing with leuprolide, circulating testosterone was increased significantly in comparison to vehicle-treated mice. Finally, in vitro metabolism of leuprolide was evaluated by incubation of leuprolide with mouse kidney membranes, followed by identification of major metabolites by MS. Such studies provide the framework for future evaluation of novel leuprolide analogs with potential therapeutic advantages.

Metabolism and anticancer activity of the curcumin analogue, dimethoxycurcumin.

PURPOSE: The plant-derived compound curcumin has shown promising abilities as a cancer chemoprevention and chemotherapy agent in vitro and in vivo but exhibits poor bioavailability. Therefore, there is a need to investigate modified curcumin congeners for improved anticancer activity and pharmacokinetic properties. EXPERIMENTAL DESIGN: The synthetic curcumin analogue dimethoxycurcumin was compared with curcumin for ability to inhibit proliferation and apoptosis of human HCT116 colon cancer cells in vitro by estimating the GI(50) and LC(50) values and detecting the extent of apoptosis by flow cytometry analysis of the cell cycle. Metabolic stability and/or identification of metabolites were evaluated by recently developed mass spectrometric approaches after incubation with mouse and human liver microsomes and cancer cells in vitro. Additionally, circulating levels of dimethoxycurcumin and curcumin were determined in mice following i.p. administration. RESULTS: Dimethoxycurcumin is significantly more potent than curcumin in inhibiting proliferation and inducing apoptosis in HCT116 cells treated for 48 h. Nearly 100% of curcumin but <30% of dimethoxycurcumin was degraded in cells treated for 48 h, and incubation with liver microsomes confirmed the limited metabolism of dimethoxycurcumin. Both compounds were rapidly degraded in vivo but dimethoxycurcumin was more stable. CONCLUSIONS: Compared with curcumin, dimethoxycurcumin is (a) more stable in cultured cells, (b) more potent in the ability to kill cancer cells by apoptosis, (c) less extensively metabolized in microsomal systems, and (d) more stable in vivo. It is likely that the differential extent of apoptosis induced by curcumin and dimethoxycurcumin in vitro is associated with the metabolite profiling and/or the extent of stability.

Change in plasma membrane Ca2(+)-ATPase splice-variant expression in response to a rise in intracellular Ca2+.

BACKGROUND: Most eukaryotic genes are divided into introns and exons. Upon transcription, the intronic segments are eliminated and the exonic sequences spliced together through a series of complex processing events. Alternative splicing refers to the optional inclusion or exclusion of specific exons in transcripts derived from a single gene, which leads to structural and functional changes in the encoded proteins. Although many components of the machinery directing the physical excision of introns and joining of exons have been elucidated in recent years, the signaling pathways regulating the activity of the machinery remain largely unexplored. RESULTS: A calcium-mediated signaling pathway regulates alternative splicing at a specific site of human plasma membrane calcium pump-2 transcripts. This site consists of three exons, which are differentially used in a tissue-specific manner. In IMR32 neuroblastoma cells, a transient elevation of intracellular calcium changed the predominant pattern from one in which all three exons are included to the coexpression of a variant including only the third exon. Western-blot analysis demonstrated that the newly expressed mRNAs are faithfully translated. Once induced, the new splicing pattern was maintained over multiple cell divisions. Protein synthesis was not required to induce the alternative splice change, indicating that all components necessary for a rapid cellular response are present in the cells. CONCLUSIONS: Calcium signaling exerts a direct influence on the regulation of alternative splicing. Notably, a calcium-mediated change in the expression of alternatively spliced variants of a calcium regulatory protein was discovered. The change in splicing occurs quickly, is persistent but reversible and leads to a corresponding change in protein expression. The specific nature in which differently spliced protein variants are expressed, and now the fact that their expression can be regulated by distinct intracellular signaling pathways, suggests that the regulation of alternative splicing by physiological stimuli is a widespread regulatory mechanism by which a cell may coordinate its responses to environmental cues.

Analysis of the in vitro metabolites of diferuloylmethane (curcumin) by liquid chromatography--tandem mass spectrometry on a hybrid quadrupole linear ion trap system: newly identified metabolites.

In this study, we have described a novel approach for determining the metabolic scheme of diferuloylmethane (curcumin) in mouse and human liver microsomal preparations using a hybrid quadrupole linear ion trap mass spectrometer coupled with liquid chromatography for the detection of new metabolites. Application of various acquisition modes allowed targeted searches for metabolites with high sensitivity and selectivity using information of the mass spectral fragmentation properties of curcumin. Structural assignments for metabolites previously reported in the literature were made with confidence using the described approach. In addition, we identified curcumin metabolites that had not previously been reported, such as curcumin bisglucuronide and O-demethylated derivatives. The major pathways of curcumin metabolism in vitro have been summarized. Finally, very similar metabolic pathways of curcumin were observed in human and mouse microsomes.

Recent advances in technology for measuring and manipulating cell signals.

Signal transduction research has made some glowing progress in the past 12 months. Recent advances in fluorescent proteins, small molecule fluorophores and imaging technology are generating new ways to investigate signal transduction.

Molecular structures of the chemical carcinogens 7-chloromethylbenz(a)anthracene and 7-chloromethyl-12-methylbenz(a)anthracene.

The three-dimensional structures of two carcinogens, 7-chloromethyl-12-methylbenz[a]anthracene and 7-chloromethylbenz[ai1anthracene, have been determined by X-ray crystallographic techniques. Both compounds are carcinogenic and are believed to act by alkylating DNA. However, the first has a nonplanar ring system, whereas the second has a planar ring system. The nonplanarity of 7-chloromethyl-12-methylbenz[a]anthracene results from steric hindrance between a hydrogen atom of the 12-methyl group and a hydrogen atom on the [a] ring. This molecule cannot be made planar unless the 12-methyl group or the [a] ring is removed. It is concluded that the carcinogenic activity of these compounds does not correlate with planarity of the ring system. This implies that, if DNA is the critical target of attack by these carcinogens, complete intercalation of the aromatic ring system of the carcinogen between the bases of DNA is not a likely mechanism of carcinogenic action in this system of compounds. The results presented here and those of others are more consistent with a model for a common interaction of the carcinogens 7-chloromethyl-12-methylbenz[a]anthracene and 7-chloromethylbenz[a]anthracene with DNA, in which they alkylate the bases of DNA and then lie with their long axes approximately parallel to the helix axis, probably in the major groove.

Molecular structure of the K-region cis-dihydrodiol of 7,12-dimethylbenz[a]anthracene.

The molecular structure and conformation of the cis-5,6-dihydrodiol of 7,12-dimethylbenz[a]anthracene has been determined by an X-ray crystallographic analysis. The compound crystallizes in the space group P21/a with cell dimensions a equals 17.799(6), b equals 33.211(8), c equals 5.241(1) A, beta equals 91.88(2)degrees. There are two molecules, designated A and B in the asymmetrical unit, that are not related to each other by crystallographic symmetry. Their conformations are almost identical, and there are no significant differences in their bond lengths or angles. In both molecules the 5-hydroxyl group is equatorial while the 6-hydroxyl group is axial. This conformation is probably forced by steric hindrance between the hydroxyl group, 0-6, and the hydrogen atoms of the 7-methyl group. The molecules pack in the crystal by forming hydrogen bonds between the hydroxyl groups of adjacent molecules, A with A, B, with B, and A with B. The ring system of the cis-5,6-dihydrodiol is much more buckled than is that in 7,12-dimethylbenz[a]anthracene itself. The angle between the two outermost rings is 36 degrees, the deviation from planarity being primarily a consequence of the partial saturation in the ring containing the two hydroxyl groups. Extrapolation of these results to other dihydrodiol derivatives of carcinogenic hydrocarbons permits some predictions of preferred molecular geometry. Thus, the 8,9-dihydrodiol-10,11-epoxide of 7,12-dimethylbenz]a[anthracene, analogous to the biologically active 7,8-dihydrodiol-9,10-epoxide of benzo]a[pyrene, a mutagen that is believed to be an active intermediate in carcinogenesis by benzo]a[pyrene, should probably exist preferentially in a conformation bearing the8-hydroxyl group in the axial orientation.

Bay region distortions in cyclopenta[a]phenanthrenes.

Two newly synthesized cyclopenta[a]phenanthrenes, namely the 1-methyl (VIII) and 7,11-dimethyl (VII) derivatives of the parent ketone 15,16-dihydrocyclopenta[a]phenanthren-17-one (I), have been tested for their capacity to produce skin tumors in mice. The former (VIII) is essentially inactive, whereas the latter (VII) is very potent in both repeated application and two-stage tests. X-ray crystallographic structure analyses have been carried out on seven derivatives of (I), namely its 11-methyl (II), 11,12-dimethyl (III), 11-methoxy (V), 11-ethyl (VI) and 7,11-dimethyl (VII) analogues (carcinogens), the 1-methyl derivative (VIII), and 11,12,15,16-tetrahydro-11-methyl-17-oxocyclopenta[a]phenanthrene (IV) (both non-carcinogens). The detailed molecular structures resulting from these studies have shown the effects of steric interactions and substitutions on the bay-region geometry. The methyl group on C(11) causes distortions of the molecule in the bay region. Out-of-plane distortions in the bay regions of the 11-methyl derivatives (II, III, VII) are greater than for the 11-methoxy or the 11-ethyl derivatives (V, VI). Molecules (except for III and IV) are packed in the crystals with interactions that include C = O...H interactions; this packing is in layers that are nearly parallel to each other. A hydrogen atom of the 11-methyl group appears, from computer modeling, to interact sterically with the hydrogen atom of the bay-region expoxide group in the activated diol-epoxide; this steric interaction may force one conformer of the diol-epoxide to be the predominant form, thereby accounting for the importance of a bay-region methyl group. Further computer modeling has been used to analyze possible modes of interaction of the diol-epoxides of cyclopenta[a]phenanthrenes with DNA.

Molecular structure of benzo(a)pyrene 4,5-oxide.

An X-ray crystallographic study of benzo(a)pyrene 4,5-oxide, a metabolite of the carcinogen benzo(a)pyrene (BP), as given information on the geometry of this molecule. The carbon skeleton of BP itself has been shown by others to be early planar; the planarity of the carbon skeleton has been shown by this work to be perturbed very little by epoxidation of the 4,5-double bond. Epoxidation has, however, increased the double bond character of C-11--C-12, C-9--C-10, and C-7--C-8. The hydrogen atom on C-3 points directly toward the oxygen atom of another molecule. This C--H... O interaction, although weak, suggests that C-3 might be slightly acidic. An analysis of the experimentally determined bond lengths indicates that, after the highly reactive epoxide ring, the most reactive positions are at C-1, C-6, C-7, C-11, and C-12. The oxide ring of BP, unlike that for the K-region oxide of 7,12-dimethylbenz(a)anthracene, is symmetrical (with C--O distances equivalent within experimental error). The C--O distances are longer than those found in most oxides, including those in 7,12-dimethylbenz(a)anthracene-5,6-oxide. Thus it has been shown that the oxide rings of the K-region oxides of the two potent carcinogens BP and 7,12-dimethylbenz(a)anthracene are not similar in dimensions.

Developmental expression of the four plasma membrane calcium ATPase (Pmca) genes in the mouse.

The plasma membrane calcium ATPases are critical components in the regulation of cellular calcium homeostasis and signaling. In mammals, there are 4 Pmca genes, and information on the cellular and tissue distribution of their expression during development will provide insight into the regulation and possible function of each Pmca isoform. Using specific probes and in situ hybridization, we found that the four Pmca genes are expressed in spatially overlapping but distinct patterns in the mouse embryo. The dynamic temporal patterns of expression indicate that the individual isoforms are subject to both positive and negative regulation. The differential and restricted expression of Pmca genes supports the notion that they play unique functional roles in mammalian development.

Benzamide-DNA interactions: deductions from binding, enzyme kinetics and from X-ray structural analysis of a 9-ethyladenine-benzamide adduct.

The interaction of benzamide with the isolated components of calf thymus poly(ADP-ribose) polymerase and with liver nuclei has been investigated. A benzamide-agarose affinity gel matrix was prepared by coupling o-aminobenzoic acid with Affi-Gel 10, followed by amidation. The benzamide-agarose matrix bound the DNA that is coenzymic with poly(ADP-ribose) polymerase; the matrix, however, did not bind the purified poly(ADP-ribose) polymerase protein. A highly radioactive derivative of benzamide, the 125I-labelled adduct of o-aminobenzamide and the Bolton-Hunter reagent, was prepared and its binding to liver nuclear DNA, calf thymus DNA and specific coenzymic DNA of poly(ADP-ribose) polymerase was compared. The binding of labelled benzamide to coenzymic DNA was several-fold higher than its binding to unfractionated calf thymus DNA. A DNA-related enzyme inhibitory site of benzamide was demonstrated in a reconstructed poly(ADP-ribose) polymerase system, made up from purified enzyme protein and varying concentrations of a synthetic octadeoxynucleotide that serves as coenzyme. As a model for benzamide binding to DNA, a crystalline complex of 9-ethyladenine and benzamide was prepared and its X-ray crystallographic structure was determined; this indicated a specific hydrogen bond between an amide hydrogen atom and N-3 of adenine. The benzamide also formed a hydrogen bond to another benzamide molecule. The aromatic ring of benzamide does not intercalate between ethyladenine molecules, but lies nearly perpendicular to the planes of stacking ethyladenine molecules in a manner reminiscent of the binding of ethidium bromide to polynucleotides. Thus we have identified DNA as a site of binding of benzamide; this binding is critically dependent on the nature of the DNA and is high for coenzymic DNA that is isolated with the purified enzyme as a tightly associated species. A possible model for such binding has been suggested from the structural analysis of a benzamide-ethyladenine complex.

Minimum CAG repeat in the human calmodulin-1 gene 5' untranslated region is required for full expression.

The human calmodulin-1 gene (hCALM1) contains a (CAG)7 repeat in its 5'-untranslated region (5'-UTR). We found this repeat to be stable and nonpolymorphic in the human population. To determine whether the repeat region affects hCALM1 expression and whether repeat expansions to numbers known to be associated with disease in other genes may alter expression, we tested luciferase reporter genes driven by the hCALM1 promoter and 5'-UTR containing 0, 7 (wild-type), 20, and 45 CAG repeats in human NT2/D1 teratoma cells. Interestingly, the repeat deletion, (CAG)0, decreased expression by 45%, while repeat expansions to (CAG)20 and (CAG)45, or the insertion of a scrambled (C,A,G)7 sequence did not alter gene expression. These data indicate (1) that the endogenous repeat element is required for full expression of hCALM1, and (2) that some triplet repeat expansions in the 5'-UTR of protein-coding genes may be well tolerated and even optimize gene expression.

Primary structure of human plasma membrane Ca(2+)-ATPase isoform 3.

The complete coding sequence of the human plasma membrane calcium ATPase (PMCA) isoform 3 was determined from overlapping genomic and cDNA clones. The cDNAs for the two major alternative splice variants 3a (3CII) and 3b (3CI) code for proteins of 1173 and 1220 amino-acid residues, respectively, which show 98% identity with the corresponding rat isoforms. On a multiple human tissue Northern blot, a major PMCA3 transcript of about 7 kb was detected exclusively in the brain, demonstrating the highly restricted pattern of expression of this isoform to human neuronal tissues. With the elucidation of the human PMCA3 primary structure, complete sequence information is now available for the entire family of human PMCA isoforms.

Filgrastim as an alternative to donor leukocyte infusion for relapse after allogeneic stem-cell transplantation.

PURPOSE: Donor leukocyte infusion (DLI) effectively treats relapse after allogeneic stem-cell transplantation (alloSCT), but the response may require several months and may be associated with significant toxicity. Filgrastim has also been observed to effectively treat leukemic relapse after alloSCT. A retrospective analysis was performed to determine the effectiveness of filgrastim in treating relapses after alloSCT. PATIENTS AND METHODS: Fourteen patients with hematologic malignancies were treated with filgrastim at relapse after alloSCT. Filgrastim was given at 5 mcg/kg/d subcutaneously for 21 consecutive days. Response was evaluated at 7 days after completion of filgrastim. Immunosuppressants, if present, were rapidly tapered to complete discontinuation at the time of relapse. RESULTS: Three patients were not assessable for response because additional therapy was necessary before completion of filgrastim. Six patients (43%) achieved a complete response on an intent-to-treat basis. When response was evaluated based on relapse type, three of four cytogenetic relapses, two of three morphologic relapses, and one of four hematologic relapses achieved a complete remission. Two responses were observed in patients who were completely off of any immunosuppression at the time of relapse. Six patients developed chronic graft-versus-host disease. The event-free and overall survival rates for all 14 patients are 43% and 73%, respectively. CONCLUSION: The use of filgrastim with rapid discontinuation of immunosuppression results in response rates that are similar to results using DLI. Filgrastim could be considered as an alternative or an adjunct to DLI for relapses after alloSCT.

Allogeneic-blood stem-cell collection following mobilization with low-dose granulocyte colony-stimulating factor.

PURPOSE: The optimal dose of granulocyte colony-stimulating factor (G-CSF) for mobilization of allogeneic-blood stem cells (AlloBSC) has yet to be determined. As part of a prospective trial, 41 related human leukocyte antigen (HLA)-matched donors had blood cells mobilized with G-CSF at 5 micrograms/kg/d by subcutaneous administration. The purpose of this trial was to monitor adverse effects during G-CSF administration and stem-cell collection, to determine the optimal timing for stem-cell collection, and to determine the cellular composition of stem-cell products following G-CSF administration. PATIENTS AND METHODS: The median donor age was 42 years. Apheresis began on day 4 of G-CSF administration. At least three daily 12-L apheresis collections were performed on each donor. A minimum of 1.0 x 10(6) CD34+ cells/kg (recipient weight) and 8.0 x 10(8) mononuclear cells/kg were collected from each donor. All collections were cryopreserved in 5% dimethyl sulfoxide and 6% hydroxyethyl starch. RESULTS: Toxicities associated with G-CSF administration and the apheresis process included myalgias/arthralgias (83%), headache (44%), fever (27%), and chills (22%). The median baseline platelet count of 242 x 10(4)/ mL decreased to 221, 155, and 119 x 10(6)/mL on days 4, 5, and 6 of G-CSF administration, respectively. Median numbers of CD34+ cells in collections 1, 2, and 3 were 1.99, 2.52, and 3.13 x 10(6)/kg, respectively. The percentage and total number of CD4+, CD8+, and CD56+/CD3- cells remained relatively constant during the three collections. Median total numbers of cells were as follows: CD34+, 7.73 x 10(6)/kg; and lymphocytes, 6.93 x 10(8)/kg. CONCLUSION: Relatively low doses of G-CSF can mobilize sufficient numbers of AlloBSC safely and efficiently.

Measurement of molecular interactions in living cells by fluorescence resonance energy transfer between variants of the green fluorescent protein.

Many signal transduction pathways operate through oligomerization of proteins into multi-subunit complexes. Although biochemical assays can identify potential protein-protein interactions, studying these interactions in living cells is more challenging. Fluorescence resonance energy transfer (FRET) has been used as a "spectroscopic ruler" to measure molecular proximity, but these methods have been limited by the need for chemical labeling of target proteins or labeled antibodies. We present methods for examining interactions between target proteins molecularly fused to cyan and yellow variants of the green fluorescent protein (GFP) by FRET in living cells. Flow cytometric and microscope-based methods are described that have been applied to a variety of interacting proteins.

Expression of high- and low-affinity neurotrophin receptors on human transformed B lymphocytes.

We performed high-sensitivity flow cytometry and Western blotting to study the expression of the low-affinity NGF receptor (p75NGFR) and of the transmembrane tyrosine kinase (Trk) family of high-affinity receptors for the different neurotrophic factors on Epstein-Barr virus (EBV)-transformed human B lymphocytes. Reverse transcriptase (RT) polymerase chain reaction (PCR) with single and multiple sets of primers (multiplex RT-PCR) was used to survey the repertoire of neurotrophin receptor transcripts in this cell line. We demonstrated that transformed B cells express detectable levels of Trk b and its mRNA. Conversely, negative results were obtained for p75NGFR, Trk a, and Trk c. Exposure of EBV-transformed B lymphocytes to brain-derived neurotrophic factor (BDNF) triggered the phosphorylation of Trk b, as demonstrated by Western blots of cell lysates probed with monoclonal antibody against phosphotyrosine.