bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mutations in Arabidopsis acyl‐CoA oxidase genes reveal distinct and overlapping roles in β‐oxidation
Authors: Adham A. Raquel , Zolman Bethany K. , Millius Arthur , Bartel Bonnie 
Published: March 2005

SummaryIndole‐3‐butyric acid (IBA) is an endogenous auxin used to enhance rooting during propagation. To better understand the role of IBA, we isolated Arabidopsis IBA‐response (ibr) mutants that display enhanced root elongation on inhibitory IBA concentrations but maintain wild‐type responses to indole‐3‐acetic acid, the principle active auxin. A subset of ibr mutants remains sensitive to the stimulatory effects of IBA on lateral root initiation. These mutants are not sucrose dependent during early seedling development, indicating that peroxisomal β‐oxidation of seed storage fatty acids is occurring. We used positional cloning to determine that one mutant is defective in ACX1 and two are defective in ACX3, two of the six Arabidopsis fatty acyl‐CoA oxidase (ACX) genes. Characterization of T‐DNA insertion mutants defective in the other ACX genes revealed reduced IBA responses in a third gene, ACX4. Activity assays demonstrated that mutants defective in ACX1, ACX3, or ACX4 have reduced fatty acyl‐CoA oxidase activity on specific substrates. Moreover, acx1 acx2 double mutants display enhanced IBA resistance and are sucrose dependent during seedling development, whereas acx1 acx3 and acx1 acx5 double mutants display enhanced IBA resistance but remain sucrose independent. The inability of ACX1, ACX3, and ACX4 to fully compensate for one another in IBA‐mediated root elongation inhibition and the ability of ACX2 and ACX5 to contribute to IBA response suggests that IBA‐response defects in acx mutants may reflect indirect blocks in peroxisomal metabolism and IBA β‐oxidation, rather than direct enzymatic activity of ACX isozymes on IBA‐CoA.
Genomics‐based selection and functional characterization of triterpene glycosyltransferases from the model legume Medicago truncatula
Authors: Achnine Lahoucine , Huhman David V. , Farag Mohamed A. , Sumner Lloyd W. , Blount Jack W. , Dixon Richard A. 
Published: March 2005

SummaryThe biosynthesis of triterpene saponins is poorly characterized in spite of the importance of these glycosylated secondary metabolites for plant defense and animal health. The model legume Medicago truncatula synthesizes more than 30 different saponins based on at least five triterpene aglycones; soyasapogenols B and E, medicagenic acid, hederagenin and bayogenin. We have employed an inducible cell culture system, DNA array‐based and in silico transcript profiling, and targeted metabolite profiling, to identify triterpene glycosyltransferases (GTs) from among the more than 300 GTs expressed in M. truncatula. Two uridine diphosphate glucosyltransferases were functionally characterized; UGT73K1 with specificity for hederagenin and soyasapogenols B and E, and UGT71G1 with specificity for medicagenic acid. The latter enzyme also glycosylated certain isoflavones and the flavonol quercetin with higher efficiency than triterpenes; however, integrated transcript and metabolite profiling supported a function for UGT71G1 in terpenoid but not (iso)flavonoid biosynthesis in the elicited cell cultures.
Silencing the nuclear actin‐related protein AtARP4 in Arabidopsis has multiple effects on plant development, including early flowering and delayed floral senescence
Authors: Kandasamy Muthugapatti K. , Deal Roger B. , McKinney Elizabeth C. , Meagher Richard B. 
Published: March 2005

SummaryActin‐related proteins (ARPs) share moderate sequence homology and basal structure with conventional actins and are found in all eukaryotes. While the functions of most of the divergent ARPs are not clear, several of them are localized to the nucleus and have been identified as components of various chromatin‐modifying complexes. Using an antibody to Arabidopsis AtARP4, we found this conserved homolog of human BAF53 and yeast Arp4 is concentrated in the nucleoplasm of Arabidopsis, Brassica, and tobacco cells. To gain further insight into the role of ARP4, we have examined Arabidopsis plants that are defective in AtARP4 expression. Phenotypic analysis of the arp4‐1 mutant allele, which has a T‐DNA insertion in the promoter region and a moderate reduction in the level of AtARP4 protein expression, revealed partial sterility due to defects in anther development. Targeting the distinct, 3′ UTR of AtARP4 transcripts with RNA interference caused a drastic reduction in the level of AtARP4 protein expression in several independent transgenic lines, and resulted in strong pleiotropic phenotypes such as altered organization of plant organs, early flowering, delayed flower senescence and high levels of sterility. Western blot analysis and immunolabeling demonstrated a clear correlation between reductions in the level of AtARP4 expression and severity of the phenotypes. Based on our results and data on the orthologs of AtARP4 in yeast and other organisms, we suggest that AtARP4 is likely to exert its effects on plant development through the modulation of chromatin structure and subsequent changes in gene regulation.
Arabidopsis mutants Atisa1 and Atisa2 have identical phenotypes and lack the same multimeric isoamylase, which influences the branch point distribution of amylopectin during starch synthesis
Authors: Delatte Thierry , Trevisan Martine , Parker Mary L. , Zeeman Samuel C. 
Published: March 2005

SummaryThe aim of this work was to evaluate the function of isoamylase in starch granule biosynthesis in Arabidopsis leaves. A reverse‐genetic approach was used to knockout AtISA1, one of three genes in Arabidopsis encoding isoamylase‐type debranching enzymes. The mutant (Atisa1‐1) lacks functional AtISA1 transcript and the major isoamylase activity (detected by native gels) in crude extracts of leaves. The same activity is abolished by mutation at the DBE1 locus, which encodes a second isoamylase‐type protein, AtISA2. This is consistent with the idea that ISA1 and ISA2 proteins are subunits of the same enzyme in vivo. Atisa1‐1, Atisa2‐1 (dbe1), and the Atisa1‐1/Atisa2‐1 double mutant all have identical phenotypes. Starch content is reduced compared with the wild type but substantial quantities of the soluble glucan phytoglycogen are produced. The amylopectin of the remaining starch and the phytoglycogen in the mutants are structurally related to each other and differ from wild‐type amylopectin. Electron micrographs reveal that the phytoglycogen‐accumulating phenotype is highly tissue‐specific. Phytoglycogen accumulates primarily in the plastids of the palisade and spongy mesophyll cells. Remarkably, other cell types appear to accumulate only starch, which is normal in appearance but is altered in structure. As phytoglycogen accumulates during the day, its rate of accumulation decreases, its structure changes and intermediates of glucan breakdown accumulate, suggesting that degradation occurs simultaneously with synthesis. We conclude that the AtISA1/AtISA2 isoamylase influences glucan branching pattern, but that this may not be the primary determinant of partitioning between crystalline starch and soluble phytoglycogen.
Greater early pancreas graft loss in women compared with men after simultaneous pancreas–kidney transplantation
Authors: Colling Christopher , Brian Stevens R , Lyden Elizabeth , Lane James , Mack‐Shipman Lynn , Wrenshall Lucile , Larsen Jennifer 
Published: March 2005

Abstract: Background:  Gender differences in graft survival has been reported after some types of organ transplantation, but not after pancreas transplantation. This study compares graft survival between women and men after simultaneous pancreas–kidney transplantation (SPK).Methods:  All first time SPK (n = 163) transplants (109 M/54 F) performed between 1989 and 2000 at University of Nebraska Medical Center, where data was available, were analyzed for overall graft and patient survival. Graft failure was then subdivided into early (<6 months), and late (>6 months), and compared between women and men.Results:  The 5‐yr pancreas and kidney graft survival rates for all SPK recipients was 86% [95% confidence interval (CI) = 81–92%] and 87% (95% CI = 82–93%), respectively. While overall pancreas graft survival in women was similar to men (p = 0.16), early pancreas graft failure was greater in women than men (p = 0.010) with no one cause for failure predominant. There was no gender difference in late pancreas graft failure or in early, or late kidney graft failure in the same recipients. The gender difference was unexplained by differences in age, immunosuppression, body mass index (BMI), or diabetes duration between women and men.Conclusions:  This is the first report of a gender difference in pancreas graft survival after SPK with greater early (<6 months) pancreas graft failure in women than men. With no gender difference in kidney graft failure in the same individuals, gender differences in immune responses are unlikely to be the cause. Multiple variables likely contribute.
Hypertension, antihypertensive agents and outcomes following renal transplantation
Authors: Tutone VK , Mark PB , Stewart GA , Tan CC , Rodger RSC , Geddes CC , Jardine AG 
Published: March 2005

Abstract:  Hypertension is common following renal transplantation and adversely affects graft and patient survival. However, strategies for antihypertensive drug therapy and target blood pressure have not been clearly defined.Aim:  To assess the influence of achieved blood pressure and antihypertension drug therapy on graft and patient survival with the aim of identifying targets and event rates for future intervention studies.Methods:  We undertook a longitudinal follow up study of 634 renal transplant patients. Patients were surveyed in December 1994 and followed up after 102 months. Blood pressure (BP) was determined from the mean of three clinic readings and antihypertensive drug therapy recorded.Results:  Complete follow up data were available for analysis on 622 patients (57.2% male; mean age: 45.2 ± 13.0 yr. There were 158 (25.4%) deaths and 115 (18.5%) death‐censored graft failures. Lower systolic and diastolic blood pressure were associated with better graft survival in the Kaplan–Meier analysis. Univariate analysis showed serum creatinine (HR 1.012, p < 0.001), duration of renal replacement therapy (HR 0.946, p = 0.012), age (HR 0.979, p = 0.014) and pulse pressure (HR 1.017, p = 0.044) to be predictors of graft survival with serum creatinine and duration of renal replacement therapy as the only significant factors in the multivariate analysis. Lower systolic and pulse pressure were associated with better patient survival in the Kaplan–Meier analysis. Age (HR) 1.062, p < 0.0001), serum creatinine (HR 1.002, p = 0.021), diabetes (HR 3.371, p < 0.0001), and pulse pressure (HR 1.013, p = 0.036) were significant predictors of patient survival in the univariate and multivariate analysis. Patient survival was reduced with increasing number of antihypertensives (p < 0.05), as was graft survival (p < 0.05). Reduced patient and graft survival were seen in patients prescribed calcium channel antagonists (p < 0.01). There was no increased patient mortality in those patients on beta‐blockers or angiotensin converting enzyme (ACE) inhibitors.Conclusion:  Hypertension is a risk factor, which remains despite the use of anti‐hypertensives, for reduced patient and graft survival. The risk was not significant when blood pressure was entered together with serum creatinine in the multivariate analysis. Beta‐blockers may have a beneficial effect on cardiovascular mortality, and ACE inhibitors a beneficial effect on both patient and graft survival. There is a pressing need for interventional studies to assess the impact of blood pressure targets on patient and graft survival and the effect of individual agents on these outcomes.
Predictors of improvement in renal function after calcineurin inhibitor withdrawal for post‐liver transplant renal dysfunction
Authors: Hong Matthew KH , Angus Peter W , Jones Robert M , Vaughan Rhys B , Gow Paul J 
Published: March 2005

Abstract:  Background:  Renal dysfunction after liver transplantation is a major management problem. Predictors of improvement in renal dysfunction after calcineurin inhibitor therapy (CNI) withdrawal and replacement with either mycophenolate mofetil (MMF) or azathioprine (AZA) have not previously been examined.Methods:  Retrospective analysis of 33 post‐transplant patients with creatinine clearance (CrCl) below 50 mL/min who were changed from CNI to either MMF or AZA. Following CNI withdrawal patients were divided into two groups: those with improved CrCl after switching and those without, to identify the variables associated with improved renal function.Results:  Variables associated with improved CrCl were: absence of hypertension or diabetes, shorter time between transplantation and switch, deterioration in CrCl in months prior to switch and treatment with MMF (compared with AZA).Conclusions:  Our findings suggest CNI withdrawal should be targeted to a subgroup of patients whose renal function is most likely to improve.
The effect of sirolimus on sex hormone levels of male renal transplant recipients
Authors: Lee Suji , Coco Maria , Greenstein Stuart M. , Schechner Richard S. , Tellis Vivian A. , Glicklich Daniel G. 
Published: March 2005

Abstract:  Background:  It is unclear whether sirolimus, a newer immunosuppressive agent, widely used in renal transplantation, affects male sex hormone levels or sexual function.Methods:  Sex hormone profiles in male renal transplant recipients were obtained and compared between a sirolimus‐treated group and a group not on sirolimus in a cross‐sectional study. Both groups also completed a sexual dysfunction questionnaire.Results:  Sixty‐six subjects were evaluated, 32 in the sirolimus group and 34 in the control group. Total testosterone level was significantly lower in the sirolimus group than the control group (393.3 ± 188 vs. 537.4 ±232 pg/mL; p = 0.08) while follicle stimulating hormone and luteinizing hormone levels were significantly higher in the sirolimus group (12.8 ± 14 vs. 6.0 ± 5, p = 0.013; 10.9 ± 14 vs. 4.7 ± 4, p = 0.018, respectively). There was a significant negative correlation between 24‐h sirolimus trough and total testosterone levels (p < 0.03). By multiple regression analysis, use of sirolimus was independently associated with decreased total testosterone level. There was no significant difference in subjective sexual dysfunction as assessed by questionnaire scores between the two groups. There was no correlation between questionnaire scores and total testosterone level.Conclusion:  Sirolimus is associated with decreased total testosterone levels in male renal transplant recipients. It is unclear whether sirolimus may affect other aspects of sexual function.
Feasibility of salvage liver transplantation for patients with recurrent hepatocellular carcinoma
Authors: Hu Rey‐Heng , Ho Ming‐Chi , Wu Yao‐Ming , Yu Seng‐Chang , Lee Po‐Huang 
Published: March 2005

Abstract:  Background:  Recurrence is the most frequent cause of treatment failure after hepatocellular carcinoma (HCC) resection. Salvage liver transplantation is an alternative treatment for recurrent HCC. The transplantability for patients with recurrent HCC has not been well studied.Study design:  This study sought to determine how many patients with recurrent HCC are still candidates for liver transplantation, and to ascertain the possible time from HCC recurrence to the loss of transplantability. In an university hospital setting, 154 of the 252 patients receiving primary HCC resection, from January 1992 through December 1996, had recurrence and were analyzed. The mean follow‐up time was 6 years. Among the 154 patients, 74 patients (group 1) were not eligible for liver transplantation according to the Milan criteria, while 80 patients were eligible (group 2). Demographic characteristics of both groups were compared and the curve of transplantability was calculated.Results:  When compared with group 1 patients, group 2 patients displayed more cirrhosis (p = 0.007), lower pTNM stage (p = 0.004), were older (p = 0.004), presented with smaller tumors (p < 0.001), and displayed a longer disease‐free interval (p < 0.001). In group 1, only 47% (35/74) patients were eligible for liver transplantation at the time of index hepatectomy, in contrast to 84% (67/80) in the group 2 patients, p < 0.001. The median time from HCC recurrence to the time they were no longer transplantable was 38 months. The total time from the index HCC resection to the time of loss of transplantability was 83 months.Conclusion:  In a cohort of patients after resection for their primary HCC, 33% patients had no recurrence and were not in need for liver transplantation in a mean follow‐up of 72 months. About 52% of the patients with recurrent HCC still meet the criteria for liver transplantation. For patients with some certain characteristics, resection of the primary HCC may postpone the time of liver transplantation and prolong the time in which a suitable donor searched, while primary liver transplantation may be considered for those patients with factors of low transplantability after recurrence.
Late anastomotic leaks in pancreas transplant recipients – clinical characteristics and predisposing factors
Authors: Nath Dilip S , Gruessner Angelika , Kandaswamy Raja , Gruessner Rainer W , Sutherland David ER , Humar Abhinav 
Published: March 2005

Abstract:  Background:  Anastomotic leaks after pancreas transplants usually occur early in the postoperative course, but may also be seen late post‐transplant. We studied such leaks to determine predisposing factors, methods of management, and outcomes.Results:  Between January 1, 1994 and December 31, 2002, a total of 25 pancreas transplant recipients at our institution experienced a late leak (defined as one occurring more than 3 months post‐transplant). We excluded recipients with an early leak or with a leak seen immediately after an enteric conversion. The mean recipient age was 40.3 yr; mean donor age, 31.3 yr. The category of transplant was as follows: simultaneous pancreas–kidney (n = 5, 20%), pancreas after kidney (n = 10, 40%), and pancreas transplant alone (n = 10, 40%). At the time of their leak, most recipients (n = 23, 92%) had bladder‐drained pancreas grafts; only two recipients (8%) had enteric‐drained grafts. The mean time from transplant to the late leak was 20.5 months (range = 3.5–74 months). A direct predisposing event or risk factor occurring in the 6 wk preceding leak diagnosis was identified in 10 (40%) of the recipients. Such events or risk factors included a biopsy‐proven episode of acute rejection (n = 4, 16%), a history of blunt abdominal trauma (n = 3, 12%), a recent episode of cytomegalovirus infection (n = 2, 8%), and obstructive uropathy from acute prostatitis (n = 1, 4%). Non‐operative or conservative care (Foley catheter placement with or without percutaneous abdominal drains) was the initial treatment in 14 (56%) of the recipients. Such care was successful in nine (64%) of the 14 recipients; the other five (36%) required surgical repair after failure of conservative care at a mean of 10 d after Foley catheter placement. Of the 25 recipients, 11 underwent surgery as their initial leak treatment: repair in nine and pancreatectomy because of severe peritonitis in two. After appropriate management (conservative or operative) of the initial leak, five (20%) of the 25 recipients had a recurrent leak; the mean length of time from initial leak to recurrent leak was 5.6 months. All five recipients with a recurrent leak ultimately required surgery.Conclusions:  Late anastomotic leaks are not uncommon; they may be more common with bladder‐drained grafts. One‐third of the recipients with a late leak had experienced some obvious preceding event that predisposed to the leak. For two‐thirds of our stable recipients with bladder‐drained grafts, non‐operative treatment of the leak was successful.
Therapeutic drug monitoring for everolimus in kidney transplantation using 12‐month exposure, efficacy, and safety data
Authors: Lorber Marc I , Ponticelli Claudio , Whelchel John , Mayer Hartmut W , Kovarik John , Li Yulan , Schmidli Heinz 
Published: March 2005

Abstract:  The aims of the current study were to determine whether therapeutic drug monitoring (TDM) might benefit kidney transplant recipients receiving everolimus, and to establish dosage recommendations when everolimus is used in combination with cyclosporine and corticosteroids. The analysis was based on data from 779 patients enrolled in two 12‐month trials. Everolimus trough concentrations ≥3 ng/mL were associated with a reduced incidence in biopsy‐proven acute rejection (BPAR) in the first month (p = 0.0001) and the first 6 months (p = 0.0001), and reduced graft loss compared with lower concentrations (4% vs. 20%, respectively). By contrast, cyclosporine in the standard concentration range had no impact on BPAR within the same timeframes. Most patients receiving everolimus 1.5 or 3 mg/d achieved trough concentrations above the therapeutic threshold of 3 ng/mL, regardless of reductions in cyclosporine dose. TDM simulation showed that just two dose adjustments would achieve median everolimus trough values ≥3 ng/mL in 95% of patients during the first 6 months.This investigation indicates that improved efficacy is likely when TDM is considered as an integral component of the immunosuppressive strategy of everolimus.
Zum Mechanismus der Ribonuclease‐Reaktion
Authors: Wieker H.‐J. , Witzel H. 
Published: March 2005

The hydrolysis of cyclic 2′,3′‐cytidylic acid (Cp) and cyclic 2′,3′‐uridylic acid (Up) by panereatic ribonuclease (E.C.2.7.7.16) at pH 7 and 5.6 is activated by adenine, adenosine, cyclic 2′,3′‐adenylic acid, and adenylyl‐adenosine (ApA). The activation is reflected by parallel shifts in the kinetic parameters when expressed on a e/v—1/s‐diagram. The measured parameters k°=π·k+2 and K°=Φ·Km are increased by the same factor, i.e.Φ=π > 1 or 1.Rate equations can be derived for an interaction of the modifier with either the substrate, the enzyme, or the enzyme‐substrate‐complex (ES), independent of any mechanistic concept. It is then possible to calculate the conditions pertaining to the relation Φ=π.The first case, an interaction between the modifier and the substrate can be excluded. In the case of an interaction between the modifier and the enzyme or ES the rate equations if Φ=π require that k−1 and k+2 are equally influenced by the modifier. Thus both constants are coupled and associated with reactions of the same type.Since the dissociation of the inhibitor 3′‐Cp from the enzyme as measured by relaxation times [21] is 103 times faster than the k+2 value in the reaction where the same 3′‐Cp is formed as the product, k+2 cannot be the dissociation of the product from the enzyme, but must be associated with a step involving bond exchange. Consequently k−1 must be associated with a step which also involves a bond exchange and is catalysed by the same principle. Both steps should therefore start from a common intermediate and lead alternatively either to the substrate (k−1) or to the product (k+2).It can be further shown that k+1 must be associated with the complementary step to k−1, also involving bond exchange, and that a simple association‐dissociation‐equilibrium between enzyme and substrate (not involving covalent bond exchanges in the substrate) does not appear in the measurable kinetic parameters. Km therefore would not represent a dissociation constant in the sense of Michaelis‐Menten but rather the ratio of the rate constants for the breakdown and the formation of an intermediate which is stabilized by the enzyme.The mathematical relations do not give any information as to the nature of the bonds exchanged or the type of catalysis. On the basis of the mechanism derived from other experiments in our previous investigations [1,3] it can be concluded now that the enzyme only induces a non‐rate‐limiting polarisation at the monoanionic phosphodiester group of the substrates. Binding would occur in a very fast non‐rate‐limiting step after the rate limiting base catalysed step when the dianionic intermediate has been formed.