bluuebunny/crossref_metadata_2025 huggingface dataset:
Acute renal transplant injury and interaction between antithymocyte globulin and pooled human immunoglobulin
Authors: Gallay Brian J , Perez Richard V , Ramsamooj Rajen
Published: May 2004

Abstract:  The increasing number of highly sensitized patients awaiting renal transplantation has prompted the use of induction immunosuppression regimens including pooled human intravenous immunoglobulin (IVIG) combined with polyclonal anti‐lymphocyte sera. We report a case of a patient who received a live donor transplant after abrogation of donor‐specific positive cytotoxic crossmatch by IVIG. She developed early acute tubular injury associated with IVIG, mannitol, and hypertonic saline infusion. Furthermore, a possible interaction between IVIG and rabbit antithymocyte globulin (ATG) occurred, suggested by an increased number of peripheral CD3+ lymphocytes after initial rapid lymphodepletion. We suggest that IVIG‐associated nephrotoxicity should be considered in the differential diagnosis of early allograft dysfunction, and furthermore, that IVIG may interact with polyclonal antilymphocyte serum to affect the amount of lymphodepletion achieved.
Preconditioning regimen consisting of anti‐CD20 monoclonal antibody infusions, splenectomy and DFPP‐enabled non‐responders to undergo ABO‐incompatible kidney transplantation
Authors: Sawada Tokihiko , Fuchinoue Shohei , Kawase Tomonori , Kubota Keiichi , Teraoka Satoshi
Published: May 2004

Abstract:  Patients undergoing ABO‐incompatible kidney transplantation must have their anti‐donor blood‐type antibody titer (ADBT) reduced to below 1:16 by using either plasma‐exchange (PEX) or double filtration plasma exchange (DFPP) before they can safely undergo a transplantation. The ADBT can be reduced to under 1:16 in most cases; however, some cases (non‐responders) do not respond to PEX or DFPP treatment. To enable kidney transplantations to be performed in non‐responders, we developed a new preconditioning regimen consisting of anti‐CD20 monoclonal antibody (rituximab) infusions, a splenectomy, and DFPP. Four non‐responders were infused with rituximab at a dose of 375 mg/m2 weekly for 3–4 wk and splenectomized 1 or 2 wk before transplantation. Four to five DFPP‐sessions were then performed after the splenectomy. Using this preconditioning regimen, the ADBT was reduced to below 1:16, enabling kidney transplantations to be successfully performed in all patients. After the kidney transplantation, no episodes of humoral rejection were observed, and only one episode of cellular rejection was encountered. The cellular rejection was associated with a reduction in immunosuppressant administration because of CMV infection that occurred 80 d after the kidney transplantation. The renal allografts were functioning well in all patients after a mean follow‐up period of 390 d. No serious complications or side effects were encountered. We have developed a new preconditioning regimen that enables PEX and DFPP non‐responders to undergo ABO‐incompatible kidney transplantations.
Impact of HCV infection on first cadaveric renal transplantation, a single center experience
Authors: Lin Hsin‐Hung , Huang Chiu‐Ching , Huang Jeng‐Yi , Yang Chih‐Wei , Wu Mai‐Szu , Fang Ji‐Tseng , Yu Chun‐Chen , Chiang Yang‐Jen , Chu Sheng‐Hsieh
Published: May 2004

Abstract: Background: Controversy still persists regarding the impact of HCV infection on renal transplant recipients. This study aimed to evaluate the effect of anti‐HCV antibody status on patients and grafts of renal transplants at a single center.

Methods: We examined 299 first cadaveric renal transplants performed between July 1981 and May 2000 at our hospital, including 129 patients with anti‐HCV antibody positive (HCV+ group) and 170 patients with anti‐HCV antibody negative (HCV− group). The HBsAg of the 299 patients were all negative throughout the follow‐up period. Causes of graft failure and patient death were analyzed. Patient and graft cumulative survival were compared between HCV+ and HCV− groups. Multivariate analysis with Cox proportional hazard model were calculated for risk hazards of outcome.

Results: Overall cumulative patient survival was 97.72, 85.63 and 71.31% at 1, 10, and 15 yr, respectively, in the HCV+ group, compared with 95.02, 67.85 and 59.83% at 1, 10 and 15 yr, respectively, in the HCV− group (p = 0.014). The major cause of patient death in both groups was infection with 26.67% in HCV+ group and 60.87% in HCV− group. Cumulative graft survival in the HCV+ group revealed 92.26, 55.97 and 26.16% at 1, 10 and 15 yr, respectively, compared with 88.07, 58.34 and 58.32% at 1, 10 and 15 yr, respectively, in the HCV− group (p = 0.700). The major cause of graft failure was chronic allograft dysfunction (56.82%) in HCV+ group, and patient death (32.43%) in the HCV− group. Multivariate analysis of patient survival revealed anti‐HCV antibody+ had lesser risk hazard (aRR: 0.30, p = 0.002), chronic hepatitis had higher risk hazard (aRR: 1.90, p = 0.135), male recipient had higher risk hazard (aRR: 2.18, p = 0.051), and older recipients (age >55) also had higher risk hazard (aRR: 4.21, p = 0.063). Analysis of graft survival revealed only older donors (age >35) had higher risk hazard (aRR: 1.90, p = 0.081).

Conclusions: The study revealed that patients with anti‐HCV antibody had higher incidence of chronic hepatitis, chronic allograft dysfunction and post‐transplantation nephrotic syndrome. Graft survival tended lower in the very long time. However, patients with anti‐HCV antibodies had better patient survival when compared with patients without HCV antibodies up to 15 yr follow up. Patients of hepatitis C group without clinical chronic hepatitis was associated with best patient survival.
Severe hemolytic anemia due to passenger lymphocytes after living‐related bowel transplant
Authors: Panaro F , DeChristopher PJ , Rondelli D , Testa G , Sankary H , Popescu M , Benedetti E
Published: May 2004

Abstract: Background: Hemolytic anemia following solid organ transplant may be caused by ‘passenger’ lymphocytes producing antibodies against erythrocytes. This phenomenon has never been described after intestinal transplant.

Materials and methods: We report a case of severe, immune‐mediated hemolysis due to symptomatic passenger lymphocyte syndrome (PLS) in a 4‐yr‐old recipient of living donor small bowel transplant. The Coombs’‐positive hemolysis was caused by anti‐A,B antibodies derived from donor lymphocytes in an ABO‐compatible donor–recipient pair (O into A).

Results: This complication was successfully and efficiently treated by the novel combined use of group O RBC transfusion, plasmapheresis and rituximab (anti‐CD20).

Conclusions: A severe hemolytic anemia due to PLS can occur in bowel transplantation. This complication should be considered when performing ABO‐incompatible bowel transplant with a blood group O donor and an A or B recipient. Treatment with plasmapheresis, blood group O transfusion and rituximab has proved successful in our case.
A long‐term study on hyperlipidemia in stable renal transplant recipients
Authors: Tse Kai‐Chung , Lam Man‐Fai , Yip Pok‐Siu , Li Fu‐Keung , Lai Kar‐Neng , Chan Tak‐Mao
Published: May 2004

Abstract: Objectives: Hyperlipidemia is a common and important risk factor after renal transplantation, but there is little long‐term data on its incidence, pattern, and evolution in stable renal allograft recipients on low dose maintenance immunosuppression.

Patients and methods: A retrospective study was conducted on all patients who received kidney transplants from April 1, 1990 to March 31, 2000 at a single center, on their serial lipid profile during the first 3 yr after kidney transplantation.

Results: A total of 221 (122 male, 99 female; mean age 37.8 ± 10.0 yr at the time of transplantation) Chinese adult renal allograft recipients were included. A 95.3% of patients were on cyclosporine and prednisolone based immunosuppression. Increases in total cholesterol (TC), low density lipoprotein (LDL), and high density lipoprotein (HDL) were noted, while the level of triglyceride (TG) decreased after renal transplant. The incidence of hypercholesterolemia (defined as TC ≥ 6.3 mmol/L or LDL ≥ 4.2 mmol/L) within the first year was 28.2 and 20.3%, respectively. The incidence rate decreased significantly in the second (5.4%, p = 0.000 and 6.4%, p = 0.003) and third year (9.5%, p = 0.003 and 4.9%, p = 0.021), but the incidence of patients having a high risk‐ratio (defined as TC/HDL ≥ 5) remained unchanged (6.9, 4.9 and 10.3% within the first, second, and third year, respectively). Treatment with statin was necessitated in 6.8, 13.6 and 21.7% of the patients at 1, 2, and 3 yr after transplantation, respectively. The prevalence rates of elevated TC and LDL were 18.3 and 18.9% at baseline, 40.6 and 33.3% after 1 yr, 32.8 and 27.3% after 2 yr, and 24.8 and 19.0% after 3 yr, despite treatment. The prevalence of patients with a high risk‐ratio was 45.0% at baseline, 30.5% after 1 yr (p = 0.002), 22.6% after 2 yr (p = 0.000) and 21.8% after 3 yr (p = 0.000). Hypercholesterolemia at the time of transplantation was an independent predictor for post‐transplant hypercholesterolemia (odds ratio 3.76, 95% confidence interval 1.47–9.62, p = 0.006).

Conclusion: Renal transplantation is associated with a characteristic pattern of dyslipidemia, with increased TC, LDL and HDL, and a decrease in TG. Patients with pre‐existing hypercholesterolemia were at higher risk for post‐transplant hypercholesterolemia. Although the incidence of hypercholesterolemia peaks within the first year after transplantation, this remains a long‐term complication in a significant proportion of patients on low dose immunosuppressive medications.
Molecular markers in subclinical acute rejection of renal transplants
Authors: Dias Esther Cristina Aquino , Veronese Francisco José Veríssimo , Gonçalves Luiz Felipe Santos , Manfro Roberto Ceratti
Published: May 2004

Abstract:  In this study, we evaluated the expression of molecular markers of acute rejection in protocol biopsies of patients with and without subclinical acute rejection (SAR). Protocol biopsies were performed at 2 months (n = 21) and 12 months (n = 14) after kidney transplantation in patients with stable allograft function. After biopsy tissue RNA isolation, reverse transcription and polymerase chain reaction (RT‐PCR) for the glyceraldehyde 3‐phospate dehydrogenase (GAPDH), perforin, granzyme B and Fas ligand genes were performed. The Banff 97 classification was used for histological diagnosis. Creatinine concentrations at 2 months were significantly higher in patients with SAR (1.46 ± 0.27 × 1.18 ± 0.24; p < 0.02). Perforin transcripts were found in 15 biopsy specimens, 10 of which had histological signs of SAR (p = 0.06). Granzyme B expression was found in 10 specimens, nine of which had SAR (p < 0.01). Fas ligand was expressed in seven specimens, and six of them were classified as SAR (p < 0.01). Perforin expression had the highest sensitivity (81%) for the diagnosis of SAR. Granzyme B and Fas ligand had specificity of 90%. At 12 months, there was no significant difference in creatinine concentrations for patients with and without previous SAR (1.63 ± 0.57 × 1.28 ± 0.31; p = 0.10). Molecular analysis revealed that there was no statistically significant difference in the expression of perforin and granzyme B in patients with and without SAR. Fas ligand expression was observed in five samples, four of which had histological signs of SAR (p = 0.03). At 12 months, perforin expression had the highest sensitivity (83%), and Fas ligand, the highest specificity (88%) for the diagnosis of SAR. We concluded that the expression of genes that encode proteins involved in the cytolytic attack against the allograft is increased in kidneys with SAR. These findings support the understanding that SAR is an active immune process potentially deleterious to renal allografts.
Apolipoprotein E gene polymorphism in renal transplant recipients: effects on lipid metabolism, atherosclerosis and allograft function
Authors: Kahraman Serkan , Kiykim Ahmet Alper , Altun Bülent , Gençtoy Gültekin , Arici Mustafa , Gulsun Meltem , Erdem Yunus , Yasavul Unal , Turgan Çetin , Çağlar Şali
Published: May 2004

Abstract:  Introduction:  Atherosclerosis is a serious complication and leading cause of mortality in renal transplant recipients (RTRs). Hyperlipidemia may be associated with progression of renal disease and chronic allograft dysfunction. Similarities in the pathogenesis of glomerulosclerosis and atherosclerosis have been proposed. Apolipoprotein (apo) E gene code forms three major isoforms (E2, E3, and E4) with variable effects on lipid metabolism.

Patients and Methods:  A total of 118 patients, at a mean age of 40 ± 8 yr, were included in the study. Apo E genotyping was carried out on genomic DNA using polymerase chain reaction and restriction enzyme. Carotid artery intima media thickness and atherosclerotic plaques were evaluated by B‐mode ultrasonography. The plasma levels of lipids and lipoproteins and acute phase reactants were also studied. Allograft function was evaluated by measuring serum creatinine and creatinine clearance values.

Results:  The frequencies of E2, E3, and E4 alleles were 0.10, 0.78, and 0.12 respectively. Carotid artery atherosclerosis was found in 25% of E2 carriers, 30% of E3 carriers, and 57% of E4 carriers. Total cholesterol, total triglyceride, low‐density lipoprotein, very low‐density lipoprotein, apo B 100 levels were found to be higher in apo E4 carriers. Median apo A1 level was higher and allograft functions were better in apo E2 carriers (p < 0.05). Multiple regression analysis showed that allograft functions were negatively correlated with elevated acute phase reactants (p < 0.01) and only the age, but not the apo E genotypes, was an independent risk factor for atherosclerotic vascular disease (p < 0.01).

Discussion:  The pathogenetic events linking lipid metabolism and allograft functions and development of atherosclerosis are complex and multifactorial in RTRs. Our results showed that apo E genotypes have influences on lipids, lipoproteins and allograft functions. The ultimate role of apo E4 gene polymorphism as a risk factor for development and progression of atherosclerosis in RTRs should be sought in further studies.
Outcome of lamivudine resistant hepatitis B virus mutant post‐liver transplantation on lamivudine monoprophylaxis
Authors: Chan Henry Lik‐Yuen , Chui Albert Ka‐Keung , Lau Wan‐Yee , Chan Francis Ka‐Leung , Hui Alex Yui , Rao Araga Ramesha Nitin , Wong John , Lai Eric Chun‐Hung , Sung Joseph Jao‐Yiu
Published: May 2004

Abstract: Background: We aimed to investigate the clinical outcome of patients who develop lamivudine resistant hepatitis B virus mutants (YMDD mutants) after liver transplantation.

Methods: Patients who received liver transplantation for hepatitis B‐related liver diseases from 1999 to 2002 were studied. All patients received lamivudine monotherapy before and after liver transplantation. HBsAg and HBV DNA were regularly monitored, and YMDD mutation was detected by direct sequencing.

Results: Twenty patients were followed up for median 94 wk (range: 15–177 wk) post‐liver transplantation. Six patients developed YMDD mutants, and the cumulative probability of developing YMDD mutations post‐liver transplantation was 21% in 1 yr and 34% in 2 yr. One patient developed YMDD mutants before liver transplantation and died of hepatitis reactivation and liver failure 15 wk post‐transplantation. The other five patients developed YMDD mutants 32–72 wk after liver transplantation. Two of them developed severe hepatitis which responded promptly to adefovir dipivoxil. The remaining three patients with YMDD mutants had minimal to mild hepatitis. The cumulative survival for patients with YMDD mutants was 83% and 28% at 1 and 2 yr, respectively. Only one patient who did not develop YMDD mutants died at week 119 due to chronic rejection. The post‐transplant survival for patients with YMDD mutants was significantly poorer than those without YMDD mutants (log rank test p = 0.083).

Conclusions: The emergence of YMDD mutants after liver transplantation on lamivudine monoprophylaxis had wide range of clinical presentations and was associated with increased mortality.
Pre‐transplant treatment of hepatocellular carcinoma: assessment of tumor necrosis in explanted livers
Authors: Wong Linda L , Tanaka Kathryn , Lau Lansdale , Komura Steven
Published: May 2004

Abstract:  Although liver transplantation (LT) is likely the most effective therapy for localized hepatocellular cancer (HCC), limited donor livers have resulted in prolonged waiting times for transplant. Pre‐transplant therapy such as transarterial chemoembolization (TACE), percutaneous ethanol injection (PEI), and radiofrequency ablation (RFA) may be needed to sustain patients who are waiting. Records, imaging studies, and pathology to identify tumor necrosis on 15 explanted livers with HCC were reviewed. Forty‐nine nodules were removed from 15 explanted livers. Five nodules in three livers that received no pre‐transplant therapy were excluded from the study. Of the remaining 44 nodules in 12 patients, 29 (66%) had 75% or more tumor necrosis. Fifteen nodules in five patients had <75% necrosis and these were due to local/non‐local recurrences or perhaps suboptimal treatment with RFA, TACE or cisplatin gel injection. Mean waiting time for LT was 162.5 d. Nine of 13 patients had a different number of nodules when listed as were seen at explant, although stage changed in only three patients. One patient died 48 months post‐LT (recurrent HCC), while the remaining patients are alive 2–55 months post‐LT. We conclude that pre‐transplant treatments for HCC are generally effective in achieving tumor necrosis. Factors involved in eventual extent of HCC seen at LT may include adequacy of treatment, accuracy of imaging techniques, local/non‐local recurrences, and time waiting for transplant. We now need to determine if tumor necrosis can allow patients to wait longer for transplant and eventually affect long‐term outcome.
Gastroparesis following kidney/pancreas transplant
Authors: Cashion AK , Holmes SL , Hathaway DK , Gaber AO
Published: May 2004

Abstract:  This pilot study examined associations among patterns of gastric myoelectrical activity, symptoms of gastroparesis, years of diabetes, months of dialysis, and use of gastrointestinal medications in gastroparetic kidney‐pancreas (KP) transplant recipients. Electrogastrography (EGG) and gastric symptom data were obtained from 42 transplant recipients before and after transplant (6, 12, and 24 months). Recipients were 38 ± 7 yr of age, 88% Whites, and 60% male; 97% had hypertension. All had functioning grafts post‐transplant (mean creatinine, 1.59 ± 0.66 mg/dL, and serum glucose 91.97 ± 24.92 mg/dL). Sixteen subjects had normal EGG (2.7–3.2 cycles per minute, cpm); two were tachygastric (>3.2 cpm) at all time points; one remained bradygastric (<2.7 cpm) throughout the study period. Following transplant, symptoms lessened and were associated with 6‐month normalization of EGG (r = 0.41, p = 0.02). A small change in the percentage of patients with normal EGG was observed from baseline to 24 months (67% vs. 69% respectively); however, there was a shift from bradygastria (29% to 15% respectively) to tachygastria (5% to 15% respectively). Prescribed prokinetic and antisecretory medications use increased over the study period from 13 (31%) subjects at baseline to 32 (86%) at 6 months; 21 (78%) at 12 months; and 12 (92%) at 24 months. Although symptoms diminish following transplant, gastroparesis remains a significant problem for transplant patients. Normalization of EGG and shifts from bradygastria to tachygastria occur post‐transplant. Our results suggest that serial EGGs and frequent assessment of symptoms can be used to follow gastroparesis in KP recipients.
A decision‐analytic economic evaluation of valaciclovir prophylaxis for the prevention of cytomegalovirus infection and disease in renal transplantation
Authors: Tilden Dominic P , Chapman Jeremy , Davey Peter J , Solly Michaela L , Crowley Steven
Published: May 2004

Abstract: Objective: This analysis evaluates the cost‐effectiveness of valaciclovir prophylaxis using clinically and economically important health outcomes including graft failure, life‐years, and quality‐adjusted life‐years (QALYs).

Methods: A Markov model was developed using a randomized, placebo‐controlled trial of valaciclovir prophylaxis, together with a published epidemiological study and national renal transplant registry data. The model's population was stratified into two risk groups by donor/recipient cytomegalovirus (CMV) serostatus at transplantation: donor‐positive/recipient‐negative (D+R−) and recipient‐positive (R+) patients. The model estimated costs and health outcomes over a 30‐yr period from the perspective of Australian health care providers.

Results: The total health care cost was $3619 lower for D+R− patients receiving valaciclovir prophylaxis compared with those not receiving prophylaxis. D+R− patients receiving valaciclovir gained an extra 0.33 yr of life and 0.27 QALYs. R+ patients receiving valaciclovir prophylaxis gained an extra 0.07 yr of life and 0.05 QALYs, with an incremental cost of $914. This equates to $17 127 per QALY gained, which is highly cost‐effective compared with other drugs and health interventions.

Conclusions: Valaciclovir for the prophylaxis of CMV disease in renal transplant recipients is a cost‐effective intervention, significantly reducing the burden of CMV disease to patients and health care providers.
Persistent dipstick haematuria following renal transplantation
Authors: McDonald Kenneth J , McMillan Margaret A , Rodger R Stuart C , Junor Brian JR , Geddes Colin C , Douglas Briggs J , Jardine Alan G
Published: May 2004

Abstract: Despite widespread testing for dipstick haematuria following renal transplantation, there are no published series describing the prevalence and possible causes of this complication in an adult population. A cross‐sectional study of 640 renal transplant recipients under review at our follow‐up clinic was performed. Persistent haematuria was defined as a minimum of 1+ of blood on urinalysis stick testing detected at not fewer than 75% of clinic visits since its onset, or since the start of routine testing, present over a period of at least 4 weeks. The prevalence of persistent dipstick haematuria was 13.3%. Median serum creatinine was higher in patients with persistent haematuria but age, gender and length of time since transplantation were not significantly different. Potential explanations for persistent haematuria in 21 of 85 affected patients were chronic infection, ureteric stent without chronic infection, regular or intermittent self‐catheterization, persistent menstrual bleeding, anticoagulant therapy, graft calculus, and allograft renal cell carcinoma. Recurrent orde novoglomerular disease was confirmed by graft biopsy in 10 of 85 patients. Among the 41 recipients whose original cause of renal failure was IgA nephropathy (IgAN), the prevalence of persistent haematuria was 31.7% compared with 12% in the remaining patients (relative risk 2.6, 95% CI: 1.6–4.3). Persistent haematuria in IgAN patients was not associated with gender, age or time since transplantation. After 29 months of follow‐up, 20% of patients with haematuria had progressed to graft failure or death compared with 11.6% of the unaffected group (p = 0.029). However, despite the association with earlier graft failure, haematuria did not predict this endpoint independently of renal function.
Expression of proopiomelanocortin and proenkephalin mRNA in sexually dimorphic brain regions are altered in adult male and female rats treated prenatally with morphine
Authors: Šlamberová R. , Hnatczuk O.C. , Vathy I.
Published: May 2004

Abstract:  The present study demonstrates that prenatal morphine exposure on gestation days 11–18 differentially alters proopiomelanocortin (POMC) and proenkephalin (pENK) mRNA in the hypothalamus and limbic system of adult male and female rats. In adult, prenatally morphine‐exposed male rats POMC mRNA levels are decreased in the arcuate nucleus of the hypothalamus (ARC), while the pENK mRNA levels are increased in the paraventricular nucleus of the hypothalamus (PVN) and in the ventrolateral subdivision of the ventromedial nucleus of the hypothalamus (VMH), specifically in the ventrolateral subdivision of the VMH. In adult, prenatally morphine‐exposed female rats, POMC mRNA levels in the ARC are increased in ovariectomized (OVX) but not in OVX, estradiol benzoate‐ (EB) or EB‐ and progesterone‐ (P) treated females. In contrast, pENK mRNA levels are decreased in the VMH of morphine‐exposed, OVX females and increased in EB‐treated females. Further, prenatal morphine exposure decreases pENK mRNA in the ARC and increases it in the medial pre‐optic area independently of female gonadal hormones. Finally, POMC mRNA levels are increased in the ARC of saline‐exposed, EB‐ or EB‐ and P‐treated females but not in OVX females. Thus, the present study suggests that prenatal morphine exposure sex and brain region specifically alters the level of POMC and pENK mRNA.
Prediction of primary structure deamidation rates of asparaginyl and glutaminyl peptides through steric and catalytic effects
Authors: Robinson N.E. , Robinson A.B.
Published: May 2004

Abstract:  The primary sequence dependence of deamidation has been quantitatively explained on the basis of a simple steric and catalytic model. Application to the known deamidation rates of peptides produces a table of coefficients that permits calculation of the known deamidation rates and prediction of deamidation rates for peptide sequences that have not yet been measured. This work permits a better understanding of deamidation, provides a prediction procedure for protein engineering, and facilitates improved computation of peptide and protein primary, secondary, tertiary, and quaternary structure deamidation rates.
Structure‐dependent nonenzymatic deamidation of glutaminyl and asparaginyl pentapeptides
Authors: Robinson N.E. , Robinson Z.W. , Robinson B.R. , Robinson A.L. , Robinson J.A. , Robinson M.L. , Robinson A.B.
Published: May 2004

Abstract:  Nonenzymatic deamidation rates for 52 glutaminyl and 52 asparaginyl pentapeptides in pH 7.4, 37.0 °C. 0.15 m Tris‐HCl buffer have been determined by direct injection mass spectrometry. These and the previously reported 306 asparginyl rates have been combined in a self‐consistent model for peptide deamidation. This model depends quantitatively upon peptide structure and involves succinimide, glutarimide and hydrolysis mechanisms. The experimental values and suitable interpolated values have been combined to provide deamidation rate values in pH 7.4, 37.0 °C. 0.15 m Tris‐HCl buffer for the entire set of 648 single‐amide permutations of ordinary amino acid residues in GlyXxxAsnYyyGly and GlyXxxGlnYyyGly. Thus, knowledge about sequence‐dependent deamidation in peptides is extended to include very long deamidation half‐times in the range of 2–50 years.
Tree–grass coexistence in savannas revisited – insights from an examination of assumptions and mechanisms invoked in existing models
Authors: Sankaran Mahesh , Ratnam Jayashree , Hanan Niall P.
Published: May 2004

Several explanations for the persistence of tree–grass mixtures in savannas have been advanced thus far. In general, these either concentrate on competition‐based mechanisms, where niche separation with respect to limiting resources such as water lead to tree–grass coexistence, or demographic mechanisms, where factors such as fire, herbivory and rainfall variability promote tree–grass persistence through their dissimilar effects on different life‐history stages of trees. Tests of these models have been largely site‐specific, and although different models find support in empirical data from some savanna sites, enough dissenting evidence exists from others to question their validity as general mechanisms of tree–grass coexistence. This lack of consensus on determinants of savanna structure and function arises because different models: (i) focus on different demographic stages of trees, (ii) focus on different limiting factors of tree establishment, and (iii) emphasize different subsets of the potential interactions between trees and grasses. Furthermore, models differ in terms of the most basic assumptions as to whether trees or grasses are the better competitors. We believe an integration of competition‐based and demographic approaches is required if a comprehensive model that explains both coexistence and the relative productivity of the tree and grass components across the diverse savannas of the world is to emerge. As a first step towards this end, we outline a conceptual framework that integrates existing approaches and applies them explicitly to different life‐history stage of trees.
Increase of atmospheric CO2 promotes phytoplankton productivity
Authors: Schippers Peter , Lürling Miquel , Scheffer Marten
Published: May 2004

It is usually thought that unlike terrestrial plants, phytoplankton will not show a significant response to an increase of atmospheric CO2. Here we suggest that this view may be biased by a neglect of the effects of carbon (C) assimilation on the pH and the dissociation of the C species. We show that under eutrophic conditions, productivity may double as a result of doubling of the atmospheric CO2 concentration. Although in practice productivity increase will usually be less, we still predict a productivity increase of up to 40% in marine species with a low affinity for bicarbonate. In eutrophic freshwater systems doubling of atmospheric CO2 may result in an increase of the productivity of more than 50%. Freshwaters with low alkalinity appeared to be very sensitive to atmospheric CO2 elevation. Our results suggest that the aquatic C sink may increase more than expected, and that nuisance phytoplankton blooms may be aggravated at elevated atmospheric CO2 concentrations.
Recovery of copepod, but not cladoceran, zooplankton from severe and chronic effects of multiple stressors
Authors: Yan Norman D. , Girard Robert , Heneberry Jocelyne H. , Keller W. Bill , Gunn John M. , Dillon Peter J.
Published: May 2004

In the mid‐twentieth century, many lakes near Sudbury, Canada, were severely contaminated by acid and metal emissions from local smelters. For example, in the early 1970s, Middle Lake had pH of 4.2, and Cu and Ni levels both >0.5 mg L−1 . To determine if crustacean zooplankton could recover from such severe and chronic damage, Middle Lake was neutralized in 1973. A comparison of its zooplankton with that of 22 reference (pH > 6) lakes indicates that the planktonic Copepoda completely recovered by 2001. In contrast, the cladoceran assemblage improved but did not recover. Colonist sources existed – Cladocera and Copepoda occurred with equal frequency in area lakes – but six separate colonizations by cladoceran species failed. We argue that local factors, metal toxicity and predation by yellow perch, have, to date, prevented cladoceran recovery. Nonetheless, the complete copepod recovery is encouraging, given the severity and duration of pre‐neutralization stress.
Moving from pattern to process: coexistence mechanisms under intermediate disturbance regimes
Authors: Shea Katriona , Roxburgh Stephen H. , Rauschert Emily S. J.
Published: May 2004

Coexistence mechanisms that require environmental variation to operate contribute importantly to the maintenance of biodiversity. One famous hypothesis of diversity maintenance under disturbance is the intermediate disturbance hypothesis (IDH). The IDH proposes patterns of peaked diversity under intermediate disturbance regimes, based on a tension between competitively superior species and species which can rapidly colonize following disturbance. We review the literature, and describe recent research that suggests that more than one underlying mechanism can generate this unimodal diversity pattern in disturbed environments. Several exciting emerging research areas are identified, including interactions between disturbance types, operation of the IDH in multi‐trophic systems, and changes in disturbance regimes. However, empirical work is still focussed on describing the IDH pattern, with little emphasis on identifying its mechanistic basis. We discuss how to extend methods for identifying different coexistence mechanisms, developed in the theoretical literature, to experimental research. In an attempt to operationalize these various ideas we outline a hypothetical IDH research programme. A solid understanding of the life history attributes of the component species and their responses to disturbance will facilitate identification of the coexistence mechanism(s) underlying the IDH pattern, and provide a framework by which empirical and theoretical results can be more fully integrated.
Abrupt community change on a rocky shore – biological mechanisms contributing to the potential formation of an alternative state
Authors: Paine Robert T. , Trimble Alan C.
Published: May 2004

The 1997/1998 El Niño initiated a major shift in the intertidal assemblage on the Washington State outer coast. A 25 year time series (1978–2003) shows stands of dominant canopy algae replaced by mussel beds. A prior experiment had indicated that mussels can become too large to be eaten by starfish; newly initiated starfish removals predict mussel attainment of a size refuge. Such escapes inhibit recovery towards prior community composition and enhance development of alternative community states which may persist long after the originating forcing has lessened or disappeared.
Removal of a specialization‐associated symbiont does not affect aphid fitness
Authors: Leonardo Teresa E.
Published: May 2004

Symbioses are ubiquitous in nature. However, these interactions, in particular those which are facultative from the perspective of the host, are still poorly understood. One major question is whether facultative symbionts affect host fitness, and in particular whether they can benefit the host. In pea aphid, host plant specialization was found to be associated with the presence of Pea Aphid U‐type Symbiont [Proc. R. Soc. Lond. B 270 (2003) S209]. Host and symbiont genomes are normally co‐transmitted, making it difficult to determine which is responsible for causing this variation in fitness. Here antibiotic treatment is used to selectively remove the symbiont, thus partitioning symbiont and host genomes. I find that PAUS is not responsible for causing host plant specialization. Examination of aphids in which PAUS presence has been naturally manipulated also supports this conclusion. Additional work will be necessary to determine the forces maintaining this symbiont in host populations, and whether it benefits the host insect under different conditions.
Bayesian inference in ecology
Authors: Ellison Aaron M.
Published: May 2004

Bayesian inference is an important statistical tool that is increasingly being used by ecologists. In a Bayesian analysis, information available before a study is conducted is summarized in a quantitative model or hypothesis: the prior probability distribution. Bayes’ Theorem uses the prior probability distribution and the likelihood of the data to generate a posterior probability distribution. Posterior probability distributions are an epistemological alternative toP‐values and provide a direct measure of the degree of belief that can be placed on models, hypotheses, or parameter estimates. Moreover, Bayesian information‐theoretic methods provide robust measures of the probability of alternative models, and multiple models can be averaged into a single model that reflects uncertainty in model construction and selection. These methods are demonstrated through a simple worked example. Ecologists are using Bayesian inference in studies that range from predicting single‐species population dynamics to understanding ecosystem processes. Not all ecologists, however, appreciate the philosophical underpinnings of Bayesian inference. In particular, Bayesians and frequentists differ in their definition of probability and in their treatment of model parameters as random variables or estimates of true values. These assumptions must be addressed explicitly before deciding whether or not to use Bayesian methods to analyse ecological data.
Tree physiological responses to above‐ground herbivory directly modify below‐ground processes of soil carbon and nitrogen cycling
Authors: Ayres Edward , Heath James , Possell Malcolm , Black Helaina I. J. , Kerstiens Gerhard , Bardgett Richard D.
Published: May 2004

Above‐ground herbivory is ubiquitous in terrestrial ecosystems, yet its impacts on below‐ground processes and consequences for plants remain ambiguous. To examine whether physiological responses of individual trees may potentially modify soil nutrient availability, we subjectedFagus sylvaticaL. (European beech) andAbies albaMill. (silver fir) to simulated foliar herbivory over two growing seasons. Above‐ground herbivory enhanced N mineralization and inorganic N availability in the soil. The total input of C from the plant roots to the soil is not known; however, carbon sequestration in the soil, measured using stable isotopic techniques, was unaffected by herbivory.Fagusresponded to herbivory by producing larger leaves, with increased photosynthetic capacity and N content, which largely compensated for the loss of biomass;Abiesexhibited no such response. We conclude that despite large interspecific differences in the growth response, tree physiological responses to foliar herbivory are capable of directly modifying soil biological processes.
Transition to Child Care: Associations With Infant–Mother Attachment, Infant Negative Emotion, and Cortisol Elevations
Authors: Ahnert Lieselotte , Gunnar Megan R. , Lamb Michael E. , Barthel Martina
Published: May 2004

Seventy 15‐month‐old infants were studied at home before starting child care, during adaptation (mothers present) and separation (first 9 days without mothers) phases, and 5 months later. Security of infant–mother attachment was assessed before and 3 months after child care began. In the separation phase, salivary cortisol rose over the first 60 min following the mothers' departures to levels that were 75% to 100% higher than at home. Compared with insecure infants, secure infants had markedly lower cortisol levels during the adaptation phase and higher fuss and cry levels during the separation phase, and their fuss and cry levels were significantly correlated with their cortisol levels. Attachments remained secure or became secure if mothers spent more days adapting their children to child care.
Genetic and Environmental Processes in Young Children's Resilience and Vulnerability to Socioeconomic Deprivation
Authors: Kim‐Cohen Julia , Moffitt Terrie E. , Caspi Avshalom , Taylor Alan
Published: May 2004

Some children exposed to socioeconomic (SES) deprivation are resilient and function better than expected, given the level of deprivation they have experienced. The present study tested genetic and environmental contributions to young children's resilience and vulnerability to SES deprivation. Children's resilience was assessed by the difference between their actual score and the score predicted by their level of SES deprivation in the E‐Risk Study, an epidemiological cohort of 1,116 five‐year‐old twin pairs. Consistent with previous research, results showed that maternal warmth, stimulating activities, and children's outgoing temperament appeared to promote positive adjustment in children exposed to SES deprivation. Findings add new information by demonstrating that resilience is partly heritable and that protective processes operate through both genetic and environmental effects.
The Time to Talk: The Influence of the Timing of Adult–Child Talk on Children's Event Memory
Authors: McGuigan Fiona , Salmon Karen
Published: May 2004

To investigate the influence of the nature and timing of adult–child talk on event recall, this study engaged 63 three‐year‐olds and 65 five‐year‐olds in a staged event and interviewed them 2 weeks later. Children were assigned to 1 of 4 conditions: elaborative pre‐, during‐, and post‐talk, and empty talk (during the event). Children in the elaborative, relative to the empty, talk conditions made fewer errors. Furthermore, post‐talk had the greatest influence on correct recall, although for the 5‐year‐olds, during‐talk was also facilitative. Recall was enhanced to a greater extent by the child's contribution to the talk, relative to that of the adult. The findings contribute to an understanding of the mechanisms by which adult–child conversations influence recall.
Children's Thinking About Diversity of Belief in the Early School Years: Judgments of Relativism, Tolerance, and Disagreeing Persons
Authors: Wainryb Cecilia , Shaw Leigh A. , Langley Marcie , Cottam Kim , Lewis Renee
Published: May 2004

Children's thinking about diversity of belief in 4 realms—morality, taste, facts, and ambiguous facts—was examined. Ninety‐six participants (ages 5, 7, and 9) were interviewed about beliefs different from their own that were endorsed by characters with different status; their judgments of relativism, tolerance, and disagreeing persons were assessed. Five‐year‐olds made fewer relative and tolerant judgments than 7‐ and 9‐year‐olds. Nevertheless, participants of all ages organized their judgments according to the realm of diversity, thought that some beliefs are relative and some are nonrelative, and made tolerant judgments of some divergent beliefs (and their proponents) but not of others. The findings suggest that, in the early school years, children have multiple and well‐differentiated perspectives on belief diversity.
Children's Developing Knowledge of the Relationship Between Mental Awareness and Pretense
Authors: Sobel David M.
Published: May 2004

This study investigated 3‐ and 4‐year‐old's understanding of the relationship between pretense and mental awareness. In Experiments 1 and 2, only a subset of 4‐year‐olds recognized that sleeping characters and characters ignorant of their appearance were not pretending. However, these experiments had certain linguistic demands, which potentially influenced performance. In Experiments 3, these demand characteristics were reduced; under these circumstances, 3‐ and 4‐year‐olds recognized that pretenders were aware of their actions or appearance. However, Experiment 4 showed that even using this modified procedure, 3‐ and 4‐year‐olds do not completely understand the relationship between pretense and awareness. These data support the hypotheses that by the age of 4, children have some, but not a complete, understanding of the relationship between pretense and mental awareness.
Forced to Choose: Some Determinants of Racial Identification in Multiracial Adolescents
Authors: Herman Melissa
Published: May 2004

This paper categorizes multiracial youth (N=1,496) ages 14 to 19 and compares them with each other and with monoracial youth on identity development measures. The multiracial categories used here are derived from youths' reports of their own and their parents' race(s). Comparisons are made within groups of multiracial respondents who make different choices among single‐race categories. Results show differences between subgroups in strength and importance of ethnic identity, self‐esteem, and perceptions of ethnic discrimination. Multinomial logistic regression shows further that physiognomy, ethnic identity, and race of coresident parent(s) are significantly associated with reported race. Also related to racial identification among part‐Hispanic youth are the racial distribution and socioeconomic status of their neighborhoods and the racial distributions of their schools.
Children's Strategies and Goals in Response to Help‐Giving and Help‐Seeking Tasks Within a Friendship
Authors: Rose Amanda J. , Asher Steven R.
Published: May 2004

The present research tested whether children's responses to help‐giving and help‐seeking friendship tasks predicted how many friends they had and the quality of their best friendship. Fifth‐grade children (N=511; typically 10 or 11 years old) responded to vignettes in which they could either give help to a friend or seek help from a friend. Children's strategies and goals in both contexts were significantly correlated with the number of friends children had. Responses in the help‐giving context but not in the help‐seeking context were significantly associated with friendship quality. Although gender differences in strategies and goals were found, strategies and goals were related to the number of friends and friendship quality for both boys and girls.
Children's Achievement Moderates the Effects of Mothers' Use of Control and Autonomy Support
Authors: Fei‐Yin Ng Florrie , Kenney‐Benson Gwen A. , Pomerantz Eva M.
Published: May 2004

Two studies investigated the effects of parents' control and autonomy support on low‐ and high‐achieving children. In Study 1, mothers' (N=110) involvement with children (7 to 10 years old) in the context of a challenging task was observed. During this interaction, mothers' control predicted diminished engagement and their autonomy support predicted enhanced performance for low‐achieving children more than for high‐achieving children. In Study 2, mothers' (N=121) responses to children's (9 to 12 years old) failure were assessed with a daily checklist. Children's grades were obtained at this time and 6 months later. Mothers' controlling responses predicted decreased performance and their autonomy‐supportive responses predicted increased performance over time for low achievers more than for high achievers.
Physiological Reactivity, Social Support, and Memory in Early Childhood
Authors: Quas Jodi A. , Bauer Amy , Boyce W. Thomas
Published: May 2004

The interactive effects of physiological reactivity and social support on children's memory were examined. Four‐ to 6‐year‐olds completed a laboratory protocol during which autonomic responses and salivary cortisol were measured. Memory was assessed shortly afterward and 2 weeks later. During the second interview, children were questioned by a supportive or nonsupportive interviewer. Few significant relations emerged between reactivity and children's short‐term memory. Following a 2‐week delay, cortisol reactivity was associated with poorer memory and autonomic reactivity was associated with increased accuracy among children questioned in a supportive manner but decreased accuracy among children questioned in a nonsupportive manner. Results question traditional conceptualizations of reactivity as a risk factor and instead suggest that reactivity may only confer risk in certain environmental contexts.
Parental Control of the Personal Domain and Adolescent Symptoms of Psychopathology: A Cross‐National Study in the United States and Japan
Authors: Hasebe Yuki , Nucci Larry , Nucci Maria S.
Published: May 2004

One hundred seventy U.S. (M=16.1 years) and 125 middle‐class Japanese (M=16.6 years) adolescents completed a questionnaire assessing perceptions of who (adolescent or parent) controls the personal, conventional, prudential, and overlapping domain behaviors of the adolescent. Participants also completed an inventory assessing self‐reported psychological symptoms. Adolescents in both countries indicated that they should have more say over personal issues and that parents should have more say over conventional and prudential issues. Self‐reports of internalizing symptoms were positively correlated with amount of perceived control over personal issues for U.S. and Japanese students and for parental control over overlapping domain issues for Japanese students. There were no associations between parental control of conventional or prudential behaviors and psychological symptoms.