Streamlining Bioactive Peptide Discovery With In Silico Prospecting: An investigation on Seaweed Pacific Dulse

Objectives

Bioactive hydrolysates and peptides from seaweed sources have been shown to exert beneficial effects in both in vitro and in vivo models for metabolic health. However, the discovery approach relies heavily on the conventional hydrolysate preparation and screening model selection, both driven by resource availability and time constraints. Considering the potential for functional food and therapeutics development, efficient and cost-effective strategies are needed to scope out as much prospect that can be screened for increased chances of hits to find potent, stable, and commercializable bioactive peptides (BAPs). This work aimed to identify multifunctional BAPs from seaweed Pacific Dulse, and to determine which hydrolytic condition can favor the release of more BAPs of interest from this protein-rich macroalgae.

Methods

Virtual hydrolysates were prepared from dulse proteins using three digestion platforms (ExPASy, SystemsBio, and Rapid Peptide Generator) under three production stream contexts (hydrolysate preparation, gastrointestinal digestion, and microbial fermentation). Peptide products were then subjected to in silico bioactivity prospecting for anti-inflammatory, antidiabetic, and antihypertensive potential. Stability in the intestine and blood was predicted along with potential toxicity. Non-toxic and stable peptides predicted to have multifunctionalities were shortlisted for bioactivity validation, and production streams predicted to generate most number of BAPs were noted for test hydrolysate production.

Results

With our approach, we identified 13 novel prospect BAPs that have multiple bioactivities, high stability, and low toxicity. Hydrolysate production using bromelain and ficin favored the 5–10aa long mBAPs generation. Simulated gastrointestinal digestion and microbial fermentation also showed promise in the release of some BAPs of interest.

Conclusions

When consumed in either hydrolyzed, whole, or fermented form, BAPs can be generated from seaweed Pacific Dulse proteins. Bioactivity testing of the novel BAPs identified, and microscale production of the promising BAP production stream are underway.

Funding Sources

Oregon Agricultural Experiment Station.

Pacific Dulse Protein: A Promising Source of Bioactive Peptides

Objectives

Pacific dulse (Devaleraea mollis) is a protein-rich seaweed in the Pacific Northwest and increasingly being cultivated as food resource. Our previous work showed that dietary supplementation of dulse exerted beneficial metabolic effects to the high-fat fed mouse model. This study aims to evaluate the potential of the seaweed protein from dulse as a precursor for bioactive peptide (BAP) generation.

Methods

The potential of Pacific dulse protein as BAP precursor was assessed using in vitro and in silico approaches. Hydrolysates were prepared from the hydrated freeze-dried protein isolates which were digested using commercial proteases. These were used for the in vitro screening for antioxidant and anti-inflammatory activities as well as the inhibition of Angiotensin-converting enzyme 1 (ACE-1), Renin, and Dipeptidyl peptidase IV (DPPIV). Peptides in the hydrolysates that exhibit the highest activities were identified using de novo sequencing. Identified peptides were shortlisted based on their potential to be

bioactive using Peptide Ranker and specific bioactivity scores were obtained using in silico platforms such as iDPPIV-SCM and PreAIP. To determine whether the consumption of the seaweed protein may help give rise to some bioactive peptides, annotated protein sequences of the seaweed material were obtained from UniProtKB and were subjected to in silico digestion using pepsin, chymotrypsin, and trypsin through BIOPEP. Bioactivity indices of the generated peptide fragments were recorded as predictive values.

Results

In silico digestion showed that dulse proteins can give rise to ACE-1, DPP-IV, and renin inhibitors, as well as antioxidant peptides. Hydrolysates exerted inhibitory effects on human ACE-1, DPPIV, and renin in vitro. ABTS radical scavenging assay and cellular antioxidant activity assay in human hepatocytes indicated the strong antioxidant potential of dulse BAP. Peptides identified through de novo sequencing had high predictive scores for DDPIV inhibition and anti-inflammatory potential.

Conclusions

Pacific dulse proteins is a promising precursor for the generation of BAPs that may exert beneficial health activities and support metabolic health improvement.

Funding Sources

Oregon State University Agricultural Research Foundation.

Recovery and Bioactivities of Pacific Dulse Protein and Its Hydrolysates

Objectives

Pacific dulse (Palmaria mollis) is a protein-rich red algae cultivated in the Pacific Northwest, originally as aquaculture feed and now expanding to human consumption. Our previous work showed that the dietary supplementation of dulse exerts anti-inflammatory effects in vivo using an obese murine model. This study aims to optimize dulse protein recovery and asses their bioactivities that may be associated to the earlier observation.

Methods

Fresh dulse samples were washed, freeze-dried and milled into powder. Effect of extraction ratio, cellulolytic enzyme addition and extractant type on protein recovery was assessed. Osborne method was employed to recover protein fractions soluble in aqueous, saline (3.5% NaCl), alkaline (0.12N NaOH) and alcoholic (70% ethanol) solutions. Dulse hydrolysates were prepared using five commercial proteases. Electrophoretic profiles were determined using SDS-PAGE. Anti-inflammatory activity of samples were tested against LPS-induced RAW 264.7 macrophages while antioxidant activity was assessed using ABTS radical scavenging assay.

Results

Extraction of Pacific dulse protein was optimal at 1:25 (wt/vol) extraction ratio. Use of 2% (vol/vol) cellulolytic enzymes enhanced the recovery by more than 2-folds. The use of Osborne method increased the protein yield as some salt-soluble and alcohol soluble proteins were also recovered. Aqueous soluble protein hydrolysates were non-cytotoxic and exerted significant anti-inflammatory activities in RAW 264.7 macrophages as evidenced by reduced LPS-induced nitrite production. Both aqueous and alkaline soluble protein and their respective hydrolysates achieved effective radical scavenging in vitro indicating antioxidant effects.

Conclusions

Our results suggest that dulse is a promising resource for bioactive proteins and peptides recovery. Further work is currently being conducted to confirm the observed bioactivities, identify active peptides, and elucidate mechanism of action.

Funding Sources

Oregon State University Agricultural Research Foundation.

Antiobesogenic Potential of Seaweed Dulse (Palmaria palmata) in High-fat Fed C57BL/6 J Mice (P21-014-19)

Objectives

The growing obesity challenge around the world continues to warrant interventions that could mitigate disease onset and progression. This study aimed to evaluate the potential of seaweed supplementation using dulse (Palmaria palmata) and wakame (Undaria pinnatifida), in improving caloric management and insulin resistance, and mitigating inflammation and gut microbiome shifts in diet-induced obesity in C57BL/6 J mice.

Methods

Twenty-four individually-caged C57BL/6 J mice were fed ad libitum with a high-fat diet (HFD) with and without seaweed inclusion, and another 8 mice for low-fat control (n = 8). Freeze-dried dulse and wakame were incorporated in the test diets at 5% inclusion level. Glucose tolerance test was performed during week 4 to assess insulin resistance state of test animals. After 9 weeks, fresh fecal samples were collected from all 32 mice prior to necropsy. These were used for the gut microbiome analysis using MiSeq. Fecal triglyceride levels were determined using Infinity Triglycerides Kit while plasma Monocyte Chemoattractant Protein-1 (MCP-1) was quantified using ELISA.

Results

Despite higher feed intake, dulse-fed mice had lower feed efficiency, indicating less weight gain from same amount of diet. This group also showed improved early-phase insulin response compared to HFD and wakame-fed groups. Plasma inflammatory marker MCP-1 levels were also significantly reduced in dulse-fed mice. While liver triglyceride levels were not affected with the dietary inclusion, fecal samples showed that there was higher lipid being excreted in dulse-fed group. This suggests that caloric excess and inflammatory progression may have been mitigated by increased lipid excretion in the feces. Gut microbiome analysis showed that dulse-fed mice retained microflora composition that is comparable to those fed with low-fat diet.

Conclusions

Our work reveals that dulse supplementation improved obesity and associated metabolic parameters by increasing lipid excretion, improving early-phase insulin response, and mitigating both inflammation and gut microbiome shifts associated with HFD, more effectively than wakame. These provide initial evidences that dietary inclusion of dulse holds therapeutic promise in mitigating diet-induced obesity.

Funding Sources

Oregon State University Agricultural Research Foundation.

Supporting Tables, Images and/or Graphs

Glucose Metabolism and Cecal Microbiome Populations Are Improved and Hepatic Biochemical Levels Altered with Consumption of Grape Powder by High-fat Fed C57BL/6 J Mice (P06-024-19)

Objectives

Grapes are nutrient-dense, particularly in polyphenolic compounds. Previous research demonstrates benefits of whole grape and grape skin, seed, and polyphenol intake on glucose homeostasis along with other health benefits. We tested the hypothesis that intake of 4 servings per day of table grape would remediate metabolic complications in C57BL/6 J (C57) male mice fed a high-fat diet with added cholesterol and fructose diet modeling an obesogenic and diabetogenic western-style diet.

Methods

Groups of mice (n = 12) were provided either low-fat plus placebo diet (LF, 10% kcal fat), high-fat plus placebo (HF, 45% kcal fat), or HF plus grape powder (HF + G), for 8 weeks. Grape powder was provided at ∼10% of total energy of diet. C57 mice were provided experimental diets ad libitum. Body weights, food intake, and glucose tolerance were determined. Postmortem, inflammatory markers, cecal microbiome, and the relative concentrations of hepatic metabolites were determined.

Results

Fasting blood glucose was reduced in the HF + G group compared to HF-fed mice. The glucose tolerance test demonstrated that the Area Under the Curve (AUC) was also reduced. Further, a significant decrease in circulating levels of insulin were observed with HF + G supplementation. The cecal microbiome from HF + G fed mice overlapped with both the HF and LF controls, but also had characteristic shifts that were unique to grape powder consumption. Metabolomic analysis indicated grape consumption impacted inflammation and β-oxidation biomarkers indicating some remediation of hepatic pathologies associated with HF food consumption. The most significantly different hepatic metabolites included grape-derived S-methymethionine and trigonelline, while other murine hepatic metabolites significantly regulated by diet included myo-inositol and 15-HETE.

Conclusions

Table grape supplementation with a HF western-style diet significantly improved fasting blood glucose, circulating insulin concentrations, and HOMA-IR in C576J/Bl male mice. demonstrating an anti-diabetic effect of grape powder. At modest level of supplementation equivalent to 4 servings/day, grape powder also improved microbiome composition and changed relative levels of specific hepatic metabolites. Up-regulation of 15-HETE by diet suggests grape powder consumption may enhance PPARγ-directed gene expression, consistent with increases in glucose sensitivity observed in this study.

Funding Sources

California Table Grape Commission.

Hepatic Metabolomic Analysis in Mice Fed a High Fat Diet with Watermelon and Watermelon Byproducts Shows Improved Lipid Metabolism and Reduction of Chronic Inflammation (P06-023-19)

Objectives

Watermelon is a nutrient-dense fruit shown previously to produce health benefits, particularly regarding blood pressure regulation. We tested the hypothesis that intake of whole watermelon flesh and value-added watermelon components would improve metabolic conditions in C57BL/6 J male mice fed a high-fat, high-sucrose diet modeling an obesogenic Western diet (HF). We further hypothesize that metabolomic profiling will show changes in relative levels of compounds related to lipid and glucose metabolism, and chronic inflammation.

Methods

In a prior study (Becraft et al., 2018), groups of mice (n = 8) were provided either low-fat diet (LF, 10% kcal fat), high-fat diet (HF, 45% kcal fat), HF plus Watermelon Skin (HF + WS), HF plus Watermelon Rind (HF + WR), or HF plus Watermelon Flesh (HF + WF) for 10 weeks. Watermelon flesh was provided at 10% of total energy and skin and rind were added at ∼ 0.2% (w/w) of diet. After ten weeks, animals were euthanized, and liver tissue saved for metabolomic analysis. Liver tissue samples were homogenized, and an identical mass equivalent of liver was subjected to methanol extraction and split into aliquots for analysis by ultrahigh performance liquid chromatography/mass spectrometry in the positive, negative or polar ion mode. There were 709 biochemicals identified and analyzed between groups. Welch's 2-sample t-test was performed with ArrayStudio (Omicsoft) or R software on log transformed data to compare data between experimental groups. Estimate of the false discovery rate (Q value) was calculated and Q ;< 0.05 used as an indication of high confidence in a result.

Results

Principal component analysis showed segregation of groups along three different components, representing 24.8%, 19.4%, and 9.0% of the variation. Profound differences were found in LF vs. HF liver tissue. Compared to HF-fed mice, mice fed WF showed reduced levels of bile acids and pro-inflammatory compounds 12-HETE, 15, HETE, and PGF2 (all P < 0.05) in the liver.

Conclusions

In mice consuming a high-fat western style diet, regular intake of watermelon flesh, and fiber-rich products made from rind and skin all improved metabolism as evidenced by metabolomic analysis of liver tissue. Most notably were reductions in pro-inflammatory compounds including HETEs and Prostaglandin F2.

Funding Sources

National Watermelon Promotion Board.

Molecular classifiers for acute kidney transplant rejection in peripheral blood by whole genome gene expression profiling

There are no minimally invasive diagnostic metrics for acute kidney transplant rejection (AR), especially in the setting of the common confounding diagnosis, acute dysfunction with no rejection (ADNR). Thus, though kidney transplant biopsies remain the gold standard, they are invasive, have substantial risks, sampling error issues and significant costs and are not suitable for serial monitoring. Global gene expression profiles of 148 peripheral blood samples from transplant patients with excellent function and normal histology (TX; n = 46), AR (n = 63) and ADNR (n = 39), from two independent cohorts were analyzed with DNA microarrays. We applied a new normalization tool, frozen robust multi-array analysis, particularly suitable for clinical diagnostics, multiple prediction tools to discover, refine and validate robust molecular classifiers and we tested a novel one-by-one analysis strategy to model the real clinical application of this test. Multiple three-way classifier tools identified 200 highest value probesets with sensitivity, specificity, positive predictive value, negative predictive value and area under the curve for the validation cohort ranging from 82% to 100%, 76% to 95%, 76% to 95%, 79% to 100%, 84% to 100% and 0.817 to 0.968, respectively. We conclude that peripheral blood gene expression profiling can be used as a minimally invasive tool to accurately reveal TX, AR and ADNR in the setting of acute kidney transplant dysfunction.

Dissemination of hepatocellular carcinoma in subcutaeous tissue after fine needle aspiration cytology (FNAC)

The hepatocellular carcinoma (HCC) is the fifth most frequent tumor in the world, and the third cause of death related to cancer. Histological samples obtained from diseased liver likely to have HCC are currently prescribed in selected patients in whose imaging studies and tumor markers are not sufficient for the diagnosis. In recent years, a risk of tumoral seeding along needle tract of FNAC to obtain histological samples has been reported. We present a case of tumor implantation of HCC cells in the needle tract, a year and four months after a percutaneous fine needle aspiration cytology (FNAC).

Can machine perfusion decrease the likelihood of discard among biopsied kidneys?

Many factors, such as donor risk factors and renal function, have been shown to be associated with an increased likelihood of discard after recovering kidneys from deceased donors. When these factors are insufficient for assessment, renal biopsy is often performed at the time of harvest to assess suitability. Our aims were to identify factors that predict the discard of a biopsied kidney and to assess the impact of machine perfusion (MP) on kidney discard. We biopsied 678 kidneys from deceased donors aged >or=40 years from 2001 to 2006. We used a logistic regression model to estimate the adjusted odds ratios for kidney discard. Thirty-nine percent (n = 261) of biopsied kidneys were discarded. Kidneys with glomerulosclerosis (GS) > 20% had the highest likelihood of discard. Other significant predictors of discard included extreme donor age, final resistance (>40), atherosclerosis, interstitial fibrosis, arteriolosclerosis, and terminal serum creatinine value (SCr) > 1.5 mg/dL. MP kidneys (n = 69) were less likely to be discarded than cold storage (CS) kidneys after adjusting for other factors (adjusted odds ratio = .13, P < .001). In conclusion, abnormal biopsy findings were associated with the highest likelihood of discard. MP was used in only 10% of the cases; however, the use of MP was associated with a decreased likelihood of discard among biopsied kidneys.

Phase 1 dose-escalation study of CP-690 550 in stable renal allograft recipients: preliminary findings of safety, tolerability, effects on lymphocyte subsets and pharmacokinetics

CP-690 550 inhibits Janus kinase 3 with nanomolar potency. In this dose-escalation study, we assessed the safety, tolerability, effects on lymphocyte subsets, and pharmacokinetics of CP-690 550 when coadministered with mycophenolate mofetil in stable renal allograft recipients for 28 days. Twenty-eight patients were enrolled. Six patients received CP-690 550 5 mg twice daily (BID), 6 patients received 15 mg BID, 10 patients received 30 mg BID, and 6 patients received placebo. The most frequent adverse events were infections and gastrointestinal (abdominal pain, diarrhea, dyspepsia, and vomiting). CP-690 550 15 mg BID and 30 mg BID were associated with a mean decrease in hemoglobin from baseline of 11% and a mean decrease in absolute natural killer cell counts of 50%. CP-690 550 30 mg BID was also associated with a mean increase in absolute CD19(+) B-lymphocytes of 130%. There were no changes in the number of neutrophils, total lymphocytes, platelets, or CD4(+) or CD8(+) T cells; clinical chemistry; vital signs; or electrocardiograms from the pretreatment baseline. Administration of CP-690 550 without a concomitant calcineurin inhibitor resulted in CP-690 550 exposures consistent with previous studies in nontransplant subjects. Additional dose-ranging studies are warranted to evaluate the safety and efficacy of CP-690 550 in renal transplant recipients over longer treatment duration.

A phase I/II randomized open-label multicenter trial of efalizumab, a humanized anti-CD11a, anti-LFA-1 in renal transplantation

Leukocyte function associated antigen-1 (LFA-1) has a multifaceted role in the immune response, including adhesion and trafficking of leukocytes, stabilizing the immune synapse of the MHC-TCR complex and providing costimulation signals. Monoclonal antibodies to the CD11a chain of LFA-1 have been seen to result in effective immunosuppression in experimental models. Efalizumab, a humanized IgG1 anti-CD11a, is approved for use in psoriasis and may provide effective immunosuppression in organ transplantation. Thirty-eight patients undergoing their first living donor or deceased renal transplant were randomized to receive efalizumab 0.5 or 2 mg/kg weekly subcutaneously for 12 weeks. Patients were maintained on full dose cyclosporine, mycophenolate mofetil and steroids or half dose cyclosporine, sirolimus and prednisone. At 6 months following transplant patient survival was 97% and graft survival was 95%. Clinical biopsy-proven acute rejection in the first 6 months after transplantation was confirmed in 4 of 38 patients (11%). Three patients (8%) developed post transplant lymphoproliferative disease, all treated with the higher dose efalizumab and full dose cyclosporine. The two doses of efalizumab resulted in comparable saturation and modulation of CD11a. This phase II trial suggests that efalizumab may warrant further investigation in transplantation.

Permanent, lowered HLA class I expression using lentivirus vectors with shRNA constructs: Averting cytotoxicity by alloreactive T lymphocytes

Transplantation of many tissues requires histocompatibility matching of human leukocyte antigens (HLA) to prevent graft rejection, to reduce the level of immunosuppression needed to maintain graft survival, and to minimize the risk of graft-versus-host disease, particularly in the case of bone marrow transplantation. However, recent advances in fields of gene delivery and genetic regulation technologies have opened the possibility of engineering grafts that display reduced levels of HLA expression. Suppression of HLA expression could help to overcome the limitations imposed by extensive HLA polymorphisms that restrict the availability of suitable donors, necessitate the maintenance of large donor registries, and complicate the logistics of procuring and delivering matched tissues and organs to the recipient. Accordingly, we investigated whether knockdown of HLA by RNA interference (RNAi), a ubiquitous regulatory system that can efficiently and selectively inhibit the expression of specific gene products, would enable allogeneic cells to evade immune recognition. For efficient and stable delivery of short hairpin-type RNAi constructs (shRNA), we employed lentivirus-based gene transfer vectors, which provide a delivery system that can achieve integration into genomic DNA, thereby permanently modifying transduced graft cells. Our results show that lentivirus-mediated delivery of shRNA targeting pan-Class I and allele-specific HLA can achieve efficient and dose-dependent reduction in surface expression of HLA in human cells, associated with enhanced resistance to alloreactive T lymphocyte-mediated cytotoxicity, while avoiding MHC-non-restricted killing. We hypothesize that RNAi-induced silencing of HLA expression has the potential to create histocompatibility-enhanced, and, eventually, perhaps "universally" compatible cellular grafts.

The 6-min walking distance: long-term follow up in patients with COPD

The 6-min walking distance (6MWD) test is used in clinical practice and research into patients with chronic obstructive pulmonary disease (COPD). However, little is known about natural long-term change in this parameter. The 6MWD was measured at baseline and then annually for 5 yrs in 294 patients with COPD and its annual rate of decline was determined. Forced expiratory volume in one second (FEV1) was also measured and the relationship between changes in both markers was explored. At baseline, the median 6MWD was 380 m (range 160-600 m). It declined by 19% (16 m.yr(-1)) over the 5 yrs compared with baseline in patients with American Thoracic Society/European Respiratory Society stage III COPD (FEV1 30-50% predicted) and by 26% (15 m.yr(-1)) in patients with stage IV COPD (FEV1 <30% pred). Over the 5-yr follow-up, the proportion of patients with a minimal clinically significant decline of 54 m increased with the severity of the disease. It was 24% in stage II, 45% in stage III, and 63% in stage IV disease. In contrast, the rate of decline of FEV1 was greater in patients with milder airflow obstruction and lesser in patients with lower absolute FEV1 values. In conclusion, the 6-min walking distance test provides increasingly useful information as the severity of chronic obstructive pulmonary disease increases.

Pulsatile perfusion reduces the incidence of delayed graft function in expanded criteria donor kidney transplantation

The use of expanded criteria donors (ECD) has been proposed to help combat the discrepancy between organ availability and need. ECD kidneys are associated with delayed graft function (DGF) and worse long-term survival. The aim of this study is to evaluate the impact of pulsatile perfusion (PP) on DGF and graft survival in transplanted ECD kidneys. From January 2000 to December 2003, 4618 ECD kidney-alone transplants were reported to the United Network for Organ Sharing. PP was performed on 912 renal allografts. The prognostic factors of DGF were analyzed using multivariate logistic regression analysis. Risk factors for reduced allograft viability were greater in donors and recipients of PP kidneys. Three-year graft survival of ECD kidneys preserved with PP was similar to cold storage (CS) kidneys. The incidence of DGF in PP kidneys was significantly lower than CS kidneys (26% vs. 36%, p < 0.001). Despite having a greater number of risk factors for reduced graft viability, the ECD-PP kidneys had similar graft survival compared to ECD-CS kidneys. The use of PP, by decreasing the incidence of DGF, may possibly lead to lower overall costs and increased utilization of donor kidneys.

Role of nucleic acid testing in cadaver organ donor screening: detection of hepatitis C virus RNA in seropositive and seronegative donors

Hepatitis C virus (HCV) transmission by both seropositive and seronegative cadaver organ donors has been documented, yet nucleic acid testing is not routinely used to identify active infection in these donors prior to transplantation. Between November 2001 and February 2004, we screened 1445 cadaver organ donors for anti-HCV antibodies with either HCV EIA-2.0 (Abbott Diagnostics, Chicago, IL, USA) and/or Ortho HCV Version 3.0 ELISA (Ortho-Clinical Diagnostics, Raritan, NJ, USA) and confirmed seropositive samples with Chiron RIBA3.0 SIA (Chiron Corporation, Emeryville, CA, USA). Samples with sufficient volume (n = 726) were tested by the VERSANT HCV [transcription-mediated amplification (TMA)] Qualitative assay (Bayer Healthcare LLC, Tarrytown, NY, USA) which can be performed in approximately 5 h. Those with detectable HCV RNA and sufficient volume were quantified by the VERSANT HCV 3.0 (bDNA) Assay (Bayer Healthcare LLC) and/or the HCV RNA TMA Quantitative Assay (n = 23) and genotyped (n = 57). Seventy-seven of 1445 (5.3%) donors were seropositive, reactive by either one or both anti-HCV assays. Fifty-two of 63 (82.5%) of the seropositive samples had detectable HCV RNA and were genotyped. Seventeen of these samples had quantifications ranging from 128,123 to >7,692,307 IU/mL. Six of 663 (0.9%) seronegative samples had detectable HCV RNA. Their quantifications ranged from <9.3 to 1,464,799 IU/mL, and five of these six were successfully genotyped. As HCV RNA was demonstrated in samples from both our seropositive and seronegative cadaver organ donors, we are now incorporating nucleic acid testing into our donor screening/diagnostic algorithm.

Significant HLA matching effect in a large urban transplant center composed primarily of minorities

In more than 1300 deceased donor transplants, including 75% Hispanics, African-Americans, and Asians, a significant effect of mismatching (MM) was observed for zero to three MM compared to more than three MM (P < .02). There was a significantly better patient survival (P < .002), shorter hospital stay (P < .001), and a trend toward lowered immunosuppression. Zero to three MM were present in 48% of the recipient population in part due to the pre-UNOS algorithm that assigns points for zero MM and other MM grades. However, recently only zero MM receive points, therefore fewer zero to three MM recipients would be expected. The largest minority population is Hispanic. We postulated that at least part of the effect was associated with socioeconomic status and English as a second language parameters of our Hispanic population. Zero to three MM was found to decrease risk and should be used prospectively in minority donor/recipient combinations.

Neutron spectra and dosimetric features around an 18 mv linac accelerator

Using the difference between responses to neutrons of TLD-600 and TLD-700, three experimental devices were constructed and arranged to measure thermal neutron fluences, neutron spectra, and neutron doses inside the treatment room of a radiotherapy 18 MV Linear electron accelerator (Linac). Thermal neutron fluences were measured with TLD-600/TLD-700 pairs arranged in both a bare and a cadmium (Cd) foil covered methacrylate box. Neutron spectra were measured in 26 energy bins by introducing pairs of TLD-600/TLD-700 in air and into the middle of five polyethylene spheres with diameters of 3, 5, 8, 10, and 12 inches. A PC version of the BUNKI code was used to unfold the six measurements in each sphere to obtain the 26 energy bins. Neutron and photon doses were measured by introducing pairs of TLD-600/TLD-700 into the middle of a single 25-cm-diameter paraffin sphere. The three required neutron calibrations were carried out at the Nuclear Technology Laboratory of the Polytechnique University of Madrid (UPM), using an 241Am-Be neutron source with an alpha activity of 111 GBq and a yield of 6.6 x 10(6) neutrons s(-1). Three devices were needed for the necessary calibrations: a BF3 counter for the thermal neutron fluence calibration, a LUDLUM 42-5 Bonner spectrometer with five 0.95 g cm(-3) polyethylene spheres with a LiI(Eu) 4 x 4 mm2 scintillation counter for the neutron spectrometer calibration and a NEMO 9140 remmeter for the paraffin remmeter calibration. The Monte Carlo code MCNP 4C has been used in two ways: to calculate the neutron kerma contribution to two TLDs (type 600 and 700) both in air and inside the paraffin sphere, and to determine the neutron spectra at those Linac room zones where the neutron spectra were measured. Thermal neutron fluences of 2.9 x 10(4) +/- 8.6 x 10(3) cm(-2) s(-1), measured around the Linac head plane, and 2.3 x 10(4) +/- 2.3 x 10(3) cm(-2) s(-1), measured at the patient couch plane, are in agreement with previous independent measurements from other authors. The calculated and measured neutron spectra obtained in the treatment room showed three distinct regions: a peak around 0.1 MeV, a flat epithermal region and a thermal region with values similar to those mentioned above. Patient dose equivalents of 0.5 mSv and 5 mSv from neutrons and photons, respectively, were obtained per treatment Gray.

Treatment of Type II Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysms: Translumbar Puncture and Injection of Thrombin into the Aneurysm Sac

OBJECTIVES

The aim of this article is to report our experience in the use of a new technique for the treatment of type II endoleaks which appear after the endovascular treatment of abdominal aortic aneurysms.

MATERIALS AND METHODS

In three patients with secondary type II endoleaks, we performed a translumbar puncture, introducing a 22-Gauge needle into the aneurysm sac under CT guidance. Once intrasac pressure had been registered, 1000U (2 ml) of human thrombin were slowly injected into the sac.

RESULTS

Complete sealing of the endoleak was achieved in all three patients, confirmed by the lack of contrast filling of the sac in the CT scans performed 5 min and 24 h after the procedure. Initial intrasac pressure was equal to systolic arterial pressure in the three patients. After the procedure, the pressure decreased by 30-40 mmHg. There were no complications during the procedure, which lasted 45-90 min. No endoleak recurrence has been observed in any of the three cases 6 months later.

CONCLUSIONS

We present an alternative method of treating type II endoleaks, which could become the treatment of choice if and when a wider experience confirms our initial good results.

A novel titrimetric method for monitoring toxicity on nitrifying biofilms

A titrimetric method for monitoring toxicity in suspended biomass was applied in order to measure the activity of nitrifying biofilms and to determine the effect of several toxic compounds on the biofilm. Three typical tannery compounds, quebracho extract, NaCl and Cr+3 were selected to study their toxicity on the biofilms. The results obtained showed an acceptable repeatability of the method for all the toxicants tested with an average standard deviation of less than 10%. Biofilm systems showed higher resistance to the toxicants, when the results obtained using suspended nitrifying biomass, were compared with those found in the literature. The IC50 obtained with quebracho was 8.8 g/L of quebracho extract, while around 65% of maximum activity was attained with 8.7 g/L of NaCl or 120 mg/L Cr+3. The quebracho extract, NaCl and Cr+3 were 26%, 38% and 18%, respectively, less toxic in the biofilm system than for a suspended biomass culture.

Carbon and nitrogen removal from tannery wastewater with a membrane bioreactor

A 3.5 L Membrane Sequencing Batch Reactor (MSBR) was used for the treatment of a wastewater coming from the beamhouse section of a tannery. The wastewater, produced after the oxidation of sulphide compounds, contained average COD and ammonium concentrations of 550 and 90 mg/L respectively. The system was operated for a period of 150 days, with no sludge removal during the whole period of operation. The biomass concentration inside the reactor varied considerably, with maximum values close to 10 g/L at the end of operation. Low biomass yield values were achieved probably due to the low feed/microorganisms (F/M) ratio. An important accumulation of organic matter in the reactor was noticed, although the COD effluent was not affected due to the permeation through the membrane. The nature of this organic matter is finally discussed. Removal efficiencies close to 100% in ammonium and 90% in COD were achieved and the TN removal efficiency ranged from 60 to 90%.

Expiratory muscle endurance in middle-aged healthy subjects

To evaluate expiratory muscle endurance in middle-aged healthy subjects using incremental as well as constant expiratory loads, 14 healthy volunteers (51 +/- 16 years) were submitted to a specific endurance test, which was performed breathing against a threshold valve, and was divided into two parts. In part I, the load was progressively increased (50 g each 2 min) until task failure occurred. The mean mouth pressure generated against the highest load held for at least 60 sec was defined as the maximal expiratory sustainable pressure (Pth(max)). In part II, each subject breathed against a constant submaximal expiratory load (80% Pth(max)) until task failure occurred (expiratory endurance time or Tth(80)). Both parts of the test were repeated 24-48 h later. Progressive expiratory loading induced a linear increase in mouth expiratory pressure and the Pth(max) obtained was 141 +/- 43 cm H(2)O, representing 74 +/- 28% of the maximal expiratory pressure (PE(max)). Under constant loads, the Tth(80) was 17 +/- 9 min. At the end-point of both parts, the tension time index for expiratory muscles was dramatically increased (>0.25), and both EMG central frequency and PE(max) were decreased with no changes in maximal inspiratory pressure or inspiratory capacity. Extreme dyspnea was present in most of the subjects but no complications were observed. The endurance of expiratory muscles can be easily assessed in healthy subjects using this method, which has acceptable reproducibility and tolerance.

Autotrophic denitrification for combined hydrogen sulfide removal from biogas and post-denitrification

In this paper we describe an alternative flow-chart for full treatment of wastewaters rich in organic substrates, ammonia (or organic nitrogen), and sulfate, such as those generated in fish cannery industries. Biogas generated during anaerobic pretreatment of these wastewaters is rich in hydrogen sulfide that needs to be removed to enable application of the biogas. Nitrogen elimination is traditionally achieved by subsequent nitrification and denitrification of the effluent of the anaerobic reactor. Alternatively, the hydrogen sulfide in the biogas can be applied as an electron donor in an autotrophic post-denitrification step. In order to study whether sufficient hydrogen sulfide containing biogas for denitrification was produced in the anaerobic reactor, the biogas composition as a function of the anaerobic reactor-pH was estimated based on a typical wastewater composition and chemical equilibrium equations. It is demonstrated that typical sulfate and nitrogen concentrations in fish cannery wastewater are highly appropriate for application of autotrophic post-denitrification. A literature review furthermore suggested that the kinetic parameters for autotrophic denitrification by Thiobacillus denitrificans represent no bottleneck for its application. Initial experimental studies in fixed-film reactors were conducted with sodium sulfide and nitrate as an electron donor-acceptor couple. The results revealed that only moderate volumetric treatment capacities (< 1 g-NO3- N l(-1) day(-1)) could be achieved. Mass balances suggested that incomplete sulfide oxidation to elemental sulfur occurred, limiting biomass retention and the treatment capacity of the reactor. Future research should clarify the questions concerning product formation from sulfide oxidation.

Rexpression of HLA class I antigens and restoration of antigen-specific CTL response in melanoma cells following 5-aza-2'-deoxycytidine treatment

Cell surface expression of HLA class I/peptide complexes on tumor cells is a key step in the generation of T-cell-based immune responses. Several genetic defects underlying the lack of HLA class I expression have been characterized. Here we describe another molecular mechanism that accounts for the complete absence of HLA class I molecule expression in a tumor line (MSR3-mel) derived from a melanoma patient. Hypermethylation of the MSR3-mel DNA, specifically of HLA-A and -B genes, was identified, which resulted in loss of HLA class I heavy chain transcription. Treatment of MSR3-mel cells with the demethylating agent 5'-aza-2'-deoxycytidine (DAC) allowed HLA-A and -B transcription, restoring cell surface expression of HLA class I antigens and tumor cell recognition by MAGE-specific cytotoxic T lymphocytes. The MSR3-mel line was obtained from a metastatic lesion of a nonresponding patient undergoing MAGE-3.A1 T-cell-based peptide immunotherapy. It is tempting to speculate that the hypermethylation-induced lack of HLA class I expression is the cause of the impaired response to vaccination. This study provides the first evidence that DNA hypermethylation is used by human neoplastic cells to switch off HLA class I genes, thus providing a new route of escape from immune recognition.

Fine-scale mapping of a locus for severe bipolar mood disorder on chromosome 18p11.3 in the Costa Rican population

We have searched for genes predisposing to bipolar disorder (BP) by studying individuals with the most extreme form of the affected phenotype, BP-I, ascertained from the genetically isolated population of the Central Valley of Costa Rica (CVCR). The results of a previous linkage analysis on two extended CVCR BP-I pedigrees, CR001 and CR004, and of linkage disequilibrium (LD) analyses of a CVCR population sample of BP-I patients implicated a candidate region on 18p11.3. We further investigated this region by creating a physical map and developing 4 new microsatellite and 26 single-nucleotide polymorphism markers for typing in the pedigree and population samples. We report the results of fine-scale association analyses in the population sample, as well as evaluation of haplotypes in pedigree CR001. Our results suggest a candidate region containing six genes but also highlight the complexities of LD mapping of common disorders.

CPEB phosphorylation and cytoplasmic polyadenylation are catalyzed by the kinase IAK1/Eg2 in maturing mouse oocytes

In both vertebrates and invertebrates, the expression of several maternal mRNAs is regulated by cytoplasmic polyadenylation. In Xenopus oocytes, where most of the biochemical details of this process have been examined, polyadenylation is controlled by CPEB, a sequence-specific RNA binding protein. The activity of CPEB, which is to recruit cleavage and polyadenylation specificity factor (CPSF) and poly(A) polymerase (PAP) into an active cytoplasmic polyadenylation complex, is controlled by Eg2-catalyzed phosphorylation. Soon after CPEB phosphorylation and resulting polyadenylation take place, the interaction between maskin, a CPEB-associated factor, and eIF4E, the cap-binding protein, is destroyed, which results in the recruitment of mRNA into polysomes. Polyadenylation also occurs in maturing mouse oocytes, although the biochemical events that govern the reaction in these cells are not known. In this study, we have examined the phosphorylation of CPEB and have assessed the necessity of this protein for polyadenylation in maturing mouse oocytes. Immunohistochemistry has revealed that all the factors that control polyadenylation and translation in Xenopus oocytes (CPEB, CPSF, PAP, maskin, and IAK1, the murine homologue of Eg2) are also present in the cytoplasm of mouse oocytes. After the induction of maturation, a kinase is activated that phosphorylates CPEB on a critical regulatory residue, an event that is essential for CPEB activity. A peptide that competitively inhibits the activity of IAK1/Eg2 blocks the progression of meiosis in injected oocytes. Finally, a CPEB protein that acts as a dominant negative mutation because it cannot be phosphorylated by IAK1/Eg2, prevents cytoplasmic polyadenylation. These data indicate that cytoplasmic polyadenylation in mouse oocytes is mediated by IAK1/Eg2-catalyzed phosphorylation of CPEB.

Hypermethylation leads to silencing of the SYK gene in human breast cancer

A number of cancer-associated genes have been shown to be inactivated by hypermethylation of CpG islands during breast tumorigenesis. SYK, a candidate tumor suppressor, has been found not expressed in a subset of breast cancer cell lines, but the mechanism by which SYK is silenced is unclear. In this study, we examined the 5' CpG island methylation status of the SYK gene in breast cancer cell lines and primary breast cancer tissues. We found SYK 5' CpG hypermethylation in 30% (6/20) of breast cancer cell lines, and the aberrant methylation status was strongly associated with loss of SYK gene expression. Treatment of cells with a methylation inhibitor, 5-aza-2'-deoxycytidine, led to a reactivation of SYK expression in SYK-negative cells, as detected by reverse transcription-PCR. Using methylation-specific PCR, we demonstrated that SYK is hypermethylated in 32% (12/37) of unselected breast tumors, whereas all of the matched neighboring normal breast tissues exhibited unmethylated DNA status. We concluded that SYK is frequently inactivated through an epigenetic pathway in breast cancer. Because SYK has been shown to function as a tumor suppressor, and its loss of expression in breast cancer has been correlated with tumor invasiveness, the aberrant SYK methylation is responsible for the loss of expression and may consequently play a permissive role for tumor aggressiveness.

Translational control by CPEB: a means to the end

The regulated translation of messenger RNA is essential for cell-cycle progression, establishment of the body plan during early development, and modulation of key activities in the central nervous system. Cytoplasmic polyadenylation, which is one mechanism of controlling translation, is driven by CPEB--a highly conserved, sequence-specific RNA-binding protein that binds to the cytoplasmic polyadenylation element, and modulates translational repression and mRNA localization. What are the features and functions of this multifaceted protein?

Analysis of HLA class I expression in different metastases from two melanoma patients undergoing peptide immunotherapy

We characterized the HLA class I alterations in five metastases obtained from two patients with melanoma immunized with Melan A/MART-1, tyrosinase and gp100 tumor peptides. All three metastases analyzed in the first patient (NW145) showed a similar HLA class I alteration with a dual population of melanoma cells. One population was HLA class I antigen positive and the other had loss of heterozygosity (LOH) in the short arm of chromosome 6 leading to an HLA haplotype loss (A02011, B4007, Cw1). The absence of HLA-A2 antigen may explain why this patient did not develop HLA-A2 restricted, Melan A/MART-1 specificity immunization, since this HLA molecule is the restriction element for the tumor peptides used. However, this HLA-deficient population was not selected after peptide immunotherapy. The primary tumor in this patient presented LOH in region 6q, but only in the vertical growth phase of the lesion, whereas LOH at 6p was observed only in DNA from metastatic material. The second patient (NW16) also presented two metastatic lesions with an identical HLA molecular defect, i.e. HLA B locus downregulation (HLA B51011: serological B51; B1503: serological B70). One lesion expressed the tumor antigen (Melan A/ MART-1), but the other did not. Interestingly, the antigen-positive metastasis regressed after peptide immunotherapy, whereas the other progressed rapidly. These findings provide the first indication that multiple metastases generated in the same host can have identically altered HLA class I phenotypes.

Genome screening for linkage disequilibrium in a Costa Rican sample of patients with bipolar-I disorder: a follow-up study on chromosome 18

Linkage disequilibrium (LD) methods offer great promise for mapping complex traits, but have thus far been applied sparingly. In this paper we describe an LD mapping study of severe bipolar disorder (BP-I) in the genetically isolated population of the Central Valley of Costa Rica. This study provides the first complete screen of a chromosome for a complex trait using LD mapping and presents the first application of a new LD mapping statistic (ancestral haplotype reconstruction (AHR)) that evaluates haplotype sharing among affected individuals. The results of this chromosome-wide analysis are instructive for genome-wide LD mapping in isolated populations. Furthermore, the analysis continues to support a possible BP-I locus on 18pter, suggested by previous analyses in this population. Evidence for a possible BP-I locus on 18q12.2 is also described.

The influence of donor age on kidney graft survival in the 1990s

Based on analyses of the UNOS Registry data for cadaver kidney transplants performed between 1991-1999 we showed that: 1. 15-40 year old donor kidneys provided the best one-year graft survival rates. When donors were analyzed with recipients, younger (0-10) and older (70-90) donors and recipients (Table 2) had the lowest one-year graft success rates. 2. Chronic loss rate, the constant rate of graft loss between one and 5 years, showed younger donor kidneys had a significantly lower chronic loss rate compared with each older donor category. Apparently the younger donor kidneys have a resiliency and nephron reserve that provides better long-term function. However, they may have lower short-term (1-yr) graft survival rates, possibly due to their small size. 3. Black and White donor kidneys had similar one-year graft survival rates; however, in every age group, recipients of White donor kidneys had significantly better 5-year graft survival rates than Black donor kidneys. There was also a noticeably lower chronic loss rate among recipients of White than Black donor kidneys. 4. HLA-matched White donor kidneys had better one- and 5-year graft survival rates and lower chronic loss rates than HLA-mismatched kidneys. The matching effect was lost when the donor age increased beyond age 40. PRA had an effect both at one and 5 years after transplantation. The chronic loss rate was similar with high and low PRA. Therefore, PRA had a relatively short-term effect. 5. Cold ischemia time had a modest effect after 35 hours both at one and 5 years. However, the chronic loss rate was unaffected by CIT, suggesting prolonged ischemia time had a relatively short-term effect. 6. More focused attention on sensitization and lowered CIT can both have a significant effect on short-term graft survival rates. However, both matching and younger donor organs provide the best opportunity for better long-term graft success rates.

Phosphorylation of CPEB by Eg2 mediates the recruitment of CPSF into an active cytoplasmic polyadenylation complex

The release of Xenopus oocytes from prophase I arrest is largely driven by the cytoplasmic polyadenylation-induced translation of dormant maternal mRNAs. Two cis elements, the CPE and the hexanucleotide AAUAAA, and their respective binding factors, CPEB and a cytoplasmic form of CPSF, control polyadenylation. The most proximal stimulus for polyadenylation is Eg2-catalyzed phosphorylation of CPEB serine 174. Here, we show that this phosphorylation event stimulates an interaction between CPEB and CPSF. This interaction is direct, does not require RNA tethering, and occurs through the 160 kDa subunit of CPSF. Eg2-stimulated and CPE-dependent polyadenylation is reconstituted in vitro using purified components. These results demonstrate that the molecular function of Eg2-phosphorylated CPEB is to recruit CPSF into an active cytoplasmic polyadenylation complex.

CPEB, maskin, and cyclin B1 mRNA at the mitotic apparatus: implications for local translational control of cell division

In Xenopus development, the expression of several maternal mRNAs is regulated by cytoplasmic polyadenylation. CPEB and maskin, two factors that control polyadenylation-induced translation are present on the mitotic apparatus of animal pole blastomeres in embryos. Cyclin B1 protein and mRNA, whose translation is regulated by polyadenylation, are colocalized with CPEB and maskin. CPEB interacts with microtubules and is involved in the localization of cyclin B1 mRNA to the mitotic apparatus. Agents that disrupt polyadenylation-induced translation inhibit cell division and promote spindle and centrosome defects in injected embryos. Two of these agents inhibit the synthesis of cyclin B1 protein and one, which has little effect on this process, disrupts the localization of cyclin B1 mRNA and protein. These data suggest that CPEB-regulated mRNA translation is important for the integrity of the mitotic apparatus and for cell division.