Autoimmune Hepatitis with Acute Presentation: Clinical, Biochemical, and Histological Features of 126 Patients.

Introduction: Autoimmune hepatitis (AIH) is a chronic liver disease with a relevant inflammatory component and an unknown etiology. Evidence for clinical characteristics and risk factors in large cohorts of patients with acute AIH (AAIH) is lacking. We clinically characterized patients with AAIH, the prevalence of a combined adverse outcome (death or liver transplantation (LT)), and its risk factors. Methods: A retrospective study of adult patients diagnosed with AAIH at three centers (Santiago, Chile; 2000-2018) was conducted. Clinical and laboratory characteristics were obtained. A liver biopsy was performed for all patients. Descriptive statistics and logistic regression models were used. Results: A total of 126 patients were admitted; 77% were female, 33 (26.2%) had a severe presentation, and 14 (11.1%) had a fulminant presentation. Overall, 24 patients (19.0%) lacked typical autoantibodies, and 26.2% had immunoglobulin G levels in the normal range. The most frequent histological findings were plasma cells (86.5%), interface hepatitis (81.7%), and chronic hepatitis (81.0%). Rosettes were uncommon (35.6%). Advanced fibrosis was present in 27% of patients. Combined adverse outcomes occurred in 7.9% of cases, all fulminant with histological cholestasis. Alkaline phosphatase, bilirubin, and prothrombin less than 50% were independent risk factors for in-hospital death or LT (p value <0.05). Although corticosteroid treatment was associated with better outcomes (OR 0.095, p value = 0.013), more severe patients were less likely to receive this therapy. Discussion. In this large cohort of patients with AAIH, clinical characteristics differ from those reported in patients with chronic AIH. Fulminant hepatitis, histological cholestasis, alkaline phosphatase, bilirubin, and prothrombin were associated with death/LT.

Generation of Chloroplast Molecular Markers to Differentiate Sophora toromiro and Its Hybrids as a First Approach to Its Reintroduction in Rapa Nui (Easter Island).

Sophora toromiro is an endemic tree of Rapa Nui with religious and cultural relevance that despite being extinct in the wild, still persists in botanical gardens and private collections around the world. The authenticity of some toromiro trees has been questioned because the similarities among hybrid lines leads to misclassification of the species. The conservation program of toromiro has the objective of its reinsertion into Rapa Nui, but it requires the exact genotyping and certification of the selected plants in order to efficiently reintroduce the species. In this study, we present for the first time the complete chloroplast genome of S. toromiro and four other Sophora specimens, which were sequenced de-novo and assembled after mapping the raw reads to a chloroplast database. The length of the chloroplast genomes ranges from 154,239 to 154,473 bp. A total of 130-143 simple sequence repeats (SSR) loci and 577 single nucleotide polymorphisms (SNPs) were identified.

Neonates from women with pregestational maternal obesity show reduced umbilical vein endothelial response to insulin.

OBJECTIVE: Pregestational maternal obesity (PGMO) associates with foetoplacental vascular endothelial dysfunction and higher risk for insulin resistance in the neonate. We characterised the PGMO consequences on the insulin response of the human foetoplacental vasculature. METHODS: Umbilical veins were from pregnancies where the mother was with PGMO (body mass index 30-42.3 kg/m2, n = 33) or normal pregestational weight (PGMN) (body mass index 19.5-24.4 kg/m2, n = 21) with total gestational weight gain within the physiological range. Umbilical vein ring segments were mounted in a myograph for isometric force measurements. Primary cultures of human umbilical vein endothelial cells were used in passage 3. Vessel rings and cells were exposed to 1 nmol/L insulin (20 min) in the absence or presence of 100 µmol/L NG-nitro-l-arginine methyl ester (inhibitor of nitric oxide synthase, NOS). RESULTS: Vessel rings from PGMO showed reduced nitric oxide synthase-activity dependent dilation to insulin or calcitonin-gene related peptide compared with PGMN. PGMO associated with higher inhibitor phosphorylation of the insulin receptor substrate 1 (IRS-1) and lower activator phosphorylation of protein kinase B/Akt (Akt). Cells from PGMO also showed lower nitric oxide level and reduced activator serine1177 but increased inhibitor threonine495 phosphorylation of endothelial nitric oxide synthase (eNOS) and saturable transport of l-arginine. HUVECs from PGMO were not responsive to insulin. CONCLUSION: The lack of response to insulin by the foetoplacental endothelium may result from reduced IRS-1/Akt/eNOS signalling in PGMO. These findings may result in higher risk of insulin resistance in neonates to PGMO pregnancies.

Hyperbaric Oxygen Increases Stem Cell Proliferation, Angiogenesis and Wound-Healing Ability of WJ-MSCs in Diabetic Mice.

Hyperbaric oxygen therapy (HBOT) is effective for the medical treatment of diverse diseases, infections, and tissue injury. In fact, in recent years there is growing evidence on the beneficial effect of HBOT on non-healing ischemic wounds. However, there is still yet discussion on how this treatment could benefit from combination with regenerative medicine strategies. Here we analyzed the effects of HBOT on three specific aspects of tissue growth, maintenance, and regeneration: (i) modulation of adult rodent (Mus musculus) intestinal stem cell turnover rates; (ii) angiogenesis dynamics during the development of the chorio-allantoic membrane (CAM) in Gallus gallus embryos; (iii) and wound-healing in a spontaneous type II diabetic mouse model with a low capacity to regenerate skin. To analyze these aspects of tissue growth, maintenance, and regeneration, we used HBOT alone or in combination with cellular therapy. Specifically, Wharton Jelly Mesenchymal Stem cells (WJ-MSC) were embedded in a commercial collagen-scaffold. HBOT did not affect the metabolic rate of adult mice nor of chicken embryos. Notwithstanding, HBOT modified the proliferation rate of stem cells in the mice small intestinal crypts, increased angiogenesis in the CAM, and improved wound-healing and tissue repair in diabetic mice. Moreover, our study demonstrates that combining stem cell therapy and HBOT has a collaborative effect on wound-healing. In summary, our data underscore the importance of oxygen tension as a regulator of stem cell biology and support the potential use of oxygenation in clinical treatments.

Expression of miR-155, miR-146a, and miR-326 in T1D patients from Chile: relationship with autoimmunity and inflammatory markers.

Objective The aim of this research was to analyze the expression profile of miR-155, miR-146a, and miR-326 in peripheral blood mononuclear cells (PBMC) of 47 patients with type 1 diabetes mellitus (T1D) and 39 control subjects, as well as the possible association with autoimmune or inflammatory markers. Subjects and methods Expression profile of miRs by means of qPCR using TaqMan probes. Autoantibodies and inflammatory markers by ELISA. Statistical analysis using bivariate correlation. Results The analysis of the results shows an increase in the expression of miR-155 in T1D patients in basal conditions compared to the controls (p < 0.001) and a decreased expression level of miR-326 (p < 0.01) and miR-146a (p < 0.05) compared T1D patients to the controls. miR-155 was the only miRs associated with autoinmmunity (ZnT8) and inflammatory status (vCAM). Conclusion Our data show a possible role of miR-155 related to autoimmunity and inflammation in Chilean patients with T1D.

Expression of miR-155, miR-146a, and miR-326 in T1D patients from Chile: relationship with autoimmunity and inflammatory markers

ABSTRACT Objective The aim of this research was to analyze the expression profile of miR-155, miR-146a, and miR-326 in peripheral blood mononuclear cells (PBMC) of 47 patients with type 1 diabetes mellitus (T1D) and 39 control subjects, as well as the possible association with autoimmune or inflammatory markers. Subjects and methods Expression profile of miRs by means of qPCR using TaqMan probes. Autoantibodies and inflammatory markers by ELISA. Statistical analysis using bivariate correlation. Results The analysis of the results shows an increase in the expression of miR-155 in T1D patients in basal conditions compared to the controls (p < 0.001) and a decreased expression level of miR-326 (p < 0.01) and miR-146a (p < 0.05) compared T1D patients to the controls. miR-155 was the only miRs associated with autoinmmunity (ZnT8) and inflammatory status (vCAM). Conclusion Our data show a possible role of miR-155 related to autoimmunity and inflammation in Chilean patients with T1D.

Insulin Is a Key Modulator of Fetoplacental Endothelium Metabolic Disturbances in Gestational Diabetes Mellitus.

Gestational diabetes mellitus (GDM) is a disease of the mother that associates with altered fetoplacental vascular function. GDM-associated maternal hyperglycaemia result in fetal hyperglycaemia, a condition that leads to fetal hyperinsulinemia and altered L-arginine transport and synthesis of nitric oxide, i.e., endothelial dysfunction. These alterations in the fetoplacental endothelial function are present in women with GDM that were under diet or insulin therapy. Since these women and their newborn show normal glycaemia at term, other factors or conditions could be altered and/or not resolved by restoring normal level of circulating D-glucose. GDM associates with metabolic disturbances, such as abnormal handling of the locally released vasodilator adenosine, and biosynthesis and metabolism of cholesterol lipoproteins, or metabolic diseases resulting in endoplasmic reticulum stress and altered angiogenesis. Insulin acts as a potent modulator of all these phenomena under normal conditions as reported in primary cultures of cells obtained from the human placenta; however, GDM and the role of insulin regarding these alterations in this disease are poorly understood. This review focuses on the potential link between insulin and endoplasmic reticulum stress, hypercholesterolemia, and angiogenesis in GDM in the human fetoplacental vasculature. Based in reports in primary culture placental endothelium we propose that insulin is a factor restoring endothelial function in GDM by reversing ERS, hypercholesterolaemia and angiogenesis to a physiological state involving insulin activation of insulin receptor isoforms and adenosine receptors and metabolism in the human placenta from GDM pregnancies.

PD-L1 gene polymorphisms and low serum level of PD-L1 protein are associated to type 1 diabetes in Chile.

INTRODUCTION: Type 1 diabetes (T1D) has a complex etiology in which genetic and environmental factors are involved, whose interactions have not yet been completely clarified. In this context, the role in PD-1 pathway and its ligands 1 and 2 (PD-L1 and PD-L2) have been proposed as candidates in several autoimmune diseases. The aim of this work was to determine the allele and haplotype frequency of six gene polymorphisms of PD-ligands (PD-L1 and PD-L2) in Chilean T1D patients and their effect on serum levels of PD-L1 and autoantibody profile (GAD65 and IA2). METHODS: This study cohort comprised 205 T1D patients and 205 normal children. We performed genotypic analysis of PD-L1 and PD-L2 genes by TaqMan method. Determination of anti-GAD65 and anti-IA-2 autoantibodies was performed by ELISA. The PD-L1 serum levels were measured. RESULTS: The allelic distribution of PD-L1 variants (rs2297137 and rs4143815) showed differences between T1D patients and controls (p = 0.035 and p = 0.022, respectively). No differences were detected among the PD-L2 polymorphisms, and only the rs16923189 showed genetic variation. T1D patients showed decreased serum levels of PD-L1 compared to controls: 1.42 [0.23-7.45] ng/mL versus 3.35 [0.49-5.89] ng/mL (p < 0.025). In addition, the CGG haplotype in PD-L1 associated with T1D (constructed from rs822342, rs2297137 and rs4143815 polymorphisms) showed an OR = 1.44 [1.08 to 1.93]. Finally, no association of these genetic variants was observed with serum concentrations of PD ligands or auto-antibody profile, although a correlation between PD-L1 ligand serum concentration and the age at disease onset was detected. CONCLUSION: Two polymorphism of PD-L1 are presented in different allelic variants between T1D and healthy subjects, also PDL-1 serum levels are significantly lowered in diabetics patients. Moreover, the age of onset of the disease determine differences between serum ligand levels in diabetics, being lower in younger. These results points to a possible establishment of PDL-1 as a genetic and biochemical marker for T1D onset, at least in Chilean population.

MicroRNAs miR-21a and miR-93 are down regulated in peripheral blood mononuclear cells (PBMCs) from patients with type 1 diabetes.

INTRODUCTION: It is well established that type 1 diabetes (T1D) is an autoimmune disease. Controversial data exists regarding the differential control of the immune system in T1D patients compared to unaffected individuals. MicroRNAs (miRNAs) are involved in the control of gene expression (by negative regulation of gene expression at post-transcriptional level, by mediating translational repression or degradation of the mRNA targets). Their potential role in T cell activation and autoimmunity is controversial. AIM: We investigated the expression profile of miR-21a and miR-93 in PMC samples of 20 T1D patients and 20 healthy controls by means of qPCR in different glucose concentrations (basal, 11 nM and 25 mM), and we analyzed the possible relationship of this expression pattern with autoimmunity. RESULTS: MiR-21a was significantly underexpressed in T1D samples (media values expression 0.23 ± 0.05, p < 0.01) compared to controls (values less than 1 indicate a decrease in gene expression). When the PMCs were incubated with glucose 11 mM and 25 mM, miR-21a expression decreased in controls and increased in T1D samples (0.506 ± 0.05, p < 0.04). MiR-93 was underexpressed in T1D patients (0.331 ± 0.05, p < 0.02) compared to control samples. However, when the PBMCs were incubated with glucose, no changes were observed. No association with autoimmunity was observed. CONCLUSION: We demonstrated that miRNAs have a differential expression in PBMCs from T1D patients compared to controls, suggesting that these miRNAs or others could be involved in T cell regulation.

High glucose concentration in T1D patients modulates apoptotic protein expression: down regulation of BAX and FAS and up regulation of XIAP.

UNLABELLED: Type 1 diabetes mellitus (T1D) is an autoimmune disease characterized by a progressive destruction of pancreatic ß cells. It has been reported that patients with autoimmune diseases exhibit decreased expression of caspase 3 and other pro-apoptotic markers in peripheral blood mononuclear cells (PBMC). AIM: To estimate the expression of apoptosis markers in PBMC from T1D patients cultured with high glucose concentration. RESULTS: At 11 mM of glucose, the pro-apoptotic gene fas showed a 7-fold decreased expression in the T1D group compared to controls, while bax showed a 50-fold decreased expression (medians 0.14 and 0.02, respectively, considering patients as 1). At 44 mM of glucose, there is a decreased expression of the same genes, but less abrupt (medians 0.75 and 0.47). Only the anti-apoptotic gene xiap showed a 2-fold increased expression at 11 mM of glucose (median 2.3). Regarding the clinical history, no relationships were observed with age of diagnosis, ketoacidosis, glucose at debut or GAD-65 and IA-2 titles. CONCLUSION: We can conclude that the apoptotic mechanisms in PBMC of T1D patients under high glucose conditions are altered, and this is proved by the decreased expression of the pro-apoptotic genes fas and bax and by the increased expression of the anti-apoptotic gene xiap.

[Hepatitis B virus immunoglobulin on demand to prevent infection recurrence among liver allograft recipients: report of three cases]. / Trasplante hepático en cirrosis por virus B: profilaxis con gammaglobulina antiHBs en dosis a "demanda".

Infection recurrence rates among hepatitis B virus infected liver allograft recipients, may be as high as 80%. Immunoprophylaxis with anti HBVgammaglobulin may reduce these rates and improve survival. The dose of anti HBV gammaglobulin that must be used is not clearly defined. The most commonly accepted protocol uses 10,000 units during the anhepatic phase and 10,000 units daily during one week, followed by weekly doses of 10,000 units during one month and maintenance with 10,000 units monthly, without measuring anti hepatitis B surface antigen antibodies (antiHBs). Some reports recommend the use of immunoglobulin on demand, to maintain antiHBs titers between 100 and 250 U/l. The infection recurrence rates among patients treated with immunoglobulin and Lamivudine fluctuates between 0 and 10%, during follow up periods of 13 to 30 months. We report three liver allograft recipients that received immunoglobulin on demand, using a mean of 41,000 units, maintaining adequate antiHBs titers.

Lactulose hydrogen breath test and functional symptoms in pediatric patients.

BACKGROUND: The role of small intestinal bacterial overgrowth (SIBO) in functional digestive disorders in the pediatric population is a matter of controversy, since methods currently used to establish this diagnosis are difficult to interpret. The aim of this work was to analyze the characteristics of the lactulose H(2) breath test (LHBT) in children with functional gastrointestinal symptoms according to more recent criteria. METHODS: Seventy-two patients and 17 controls were enrolled. A questionnaire was administered regarding digestive symptoms (abdominal pain, bloating, vomiting, and bowel-movement disorders). A lactose hydrogen breath test was performed to rule out lactose malabsorption and a LHBT was used to measure the time elapsed between lactulose oral ingestion and an increment of H(2) concentration of 20 ppm over basal. RESULTS: There were no differences of age and gender between patients and controls. Mean time to 20-ppm change was shorter in patients (56.3 ± 3 min) compared to healthy children (74.7 ± 5 min), p\0.05. In 39% of patients, rise of H(2) occurred during the first 40 min after lactulose ingestion, and in almost all controls, an increment was observed between 50 and 90 min (p\0.05). Symptoms were unrelated to time to 20-ppm change. CONCLUSIONS: An abnormal LHBT was found in children with functional symptoms of the digestive tract, but the exact mechanism involved, accelerated intestinal transit or SIBO, needs to be confirmed by an additional method.

Trasplante hepático en cirrosis por virus B: profilaxis con gammaglobulina antiHBs en dosis a "demanda" / Hepatitis B virus immunoglobulin on demand to prevent infection recurrence among liver allograft recipients: Report of three cases

Infection recurrence rates among hepatitis B virus infected liver allograft recipients, may be as high as 80%. Immunoprophylaxis with anti HBVgammaglobulin may reduce these rates and improve survival. The dose of anti HBV gammaglobulin that must be used is not clearly defined. The most commonly accepted protocol uses 10,000 units during the anhepatic phase and 10,000 units daily during one week, followed by weekly doses of 10,000 units during one month and maintenance with 10,000 units monthly, without measuring anti hepatitis B surface antigen antibodies (antiHBs). Some reports recommend the use of immunoglobulin on demand, to maintain antiHBs titers between 100 and 250 U/l. The infection recurrence rates among patients treated with immunoglobulin and Lamivudine fluctuates between 0 and 10%, during follow up periods of 13 to 30 months. We report three liver allograft recipients that received immunoglobulin on demand, using a mean of41,000 units, maintaining adequate antiHBs titers.

[Decreased caspase 3 expression and cytotoxic T lymphocyte antigen-4 polymorphism in Chilean patients with type 1 diabetes]. / Expresión disminuida de caspasa 3 asociada al polimorfismo del gen del antígeno-4 asociado a linfocito T-citotóxico (CTLA4) en pacientes chilenos con diabetes tipo 1.

BACKGROUND: Several polymorphisms of the CTLA4 gene have been associated with autoimmune diseases. The activation of induced cell death is the major event and caspase 3 represents the main protein for the apoptotic machinery, especially in lymphocytes. AIM: To correlate CTLA4 polymorphisms with caspase 3 expression in peripheral blood mononuclear cells (PBMC) simulating in vitro the glucose effect. MATERIAL AND METHODS: CTLA4 polymorphisms were determined by restriction fragment length polymorphisms (RFLPs). PBMC from 21 patients with type 1 diabetes aged 8.5 ± 4.3 years and 21 healthy subjects aged 18.3 ± 1.8 years, were stimulated under normal (5 mM) and toxic (14 mM) glucose conditions to assess its effect on the expression and activity of caspase 3. Relative abundance of caspase 3 mRNA was measured by semi quantitative RT-PCR and its activity, by a colorimetric assay. RESULTS: When stimulated with 14 mM glucose, PBMC of G allele carriers with type 1 diabetes had significantly lower relative mRNA abundance of caspase 3 (median value = 0.12, range 0.01-0.70 AU) compared with non-carriers (median value = 0.81, range 0.06-1.09 AU). When the incubation was carried out with the lower glucose concentration, a similar profile of caspase 3 activity was observed in diabetic patients carrying G allele (median value = 0.57, range 0.13-1.20 AU) as compared with non-carriers (median value = 0.89, range 0.14-5.50 AU). No significant changes after stimulating with glucose, were observed in PBMCs of the control group. CONCLUSIONS: PBMC of recently diagnosed patients with T1D, carrying the G allele in + 49A/G polymorphisms of CTLA4, have a decreased expression and activity of caspase 3.

[Results of treatment with peginterferon plus ribavirin in patients with chronic hepatitis C]. / Resultados del tratamiento con peginterferón alfa-2a y ribavirina en pacientes con hepatitis crónica C.

BACKGROUND: The current treatment recommendation for chronic hepatitis C virus infection is the combination of peginterferon and ribavirin for 24 or 48 weeks, depending on the viral genotype. The aim of the therapy is to obtain a sustained virological response. AIM: To report our experience in the treatment of chronic hepatitis C. MATERIAL AND METHODS: Analysis of 52 patients treated between September 2000 and June 2009. Patients with genotype 1 or 5 were treated with peginterferon alpha 2a (180 ug/week) and ribavirin (1000 mg/day for those weighing less than 75 kg and 1200 mg/day for those weighing more than 75 kg) during 48 weeks. Patients with genotypes 2 and 3 were treated for 24 weeks with the same dose of peginterferon and ribavirin 800 mg/day. RESULTS: Viral genotypes 1, 2, 3 and 5 were present in 81, 4, 11 and 4% of patients, respectively. Twenty four patients (46 %), 18 with genotype 1, achieved a sustained viral response. Age was the only variable that influenced the response to treatment. CONCLUSIONS: Approximately half of the patients with chronic hepatitis C, achieve a sustained viral response with peginterferon and ribavirin.

Biofilm formation for organic matter and sulphate removal in gas-lift reactors

A start-up strategy was presented and evaluated to obtain a well-established biofilm in a gas lift-reactor capable both for the removal of organic matter and sulphate. Pumice stone was used as material support. The influence of shear forces, given by the biogas recirculation, the effect of the COD/SO4-2 ratio and the OLRs increase were evaluated on the reactor performance. From the first stages, cell colonization was observed along with the presence of extracellular polymeric substances. The COD and sulphate removal was over 70 percent, for all conditions. The increase of gas flow did not have an adverse effect on biofilm development even though there was some detachment. Specific methanogenic activity of the biofilm increased along the experiments. Operational parameters as alkalinity and alkalinity ratio were within the recommended values for the operation with sulphate-rich wastewater. For gas-lift reactors operation it becomes fundamental to have a suitable start-up strategy that takes into account the initial biofilm development from a non-acclimatized biomass.

Resultados del tratamiento con peginterferón alfa-2a y ribavirina en pacientes con hepatitis crónica C / Results of treatment with peginterferon plus ribavirin in patients with chronic hepatitis C

Background: The current treatment recommendation for chronic hepatitis C virus infection is the combination of peginterferon and ribavirin for 24 or 48 weeks, depending on the viral genotype. The aim of the therapy is to obtain a sustained virological response. Aim: To report our experience in the treatment of chronic hepatitis C. Material and Methods: Analysis of 52 patients treated between September 2000 and June 2009. Patients with genotype 1 or 5 were treated with peginterferon alpha 2a (180 ug/week) and ribavirin (1000 mg/day for those weighing less than 75 kg and 1200 mg/day for those weighing more than 75 kg) during 48 weeks. Patients with genotypes 2 and 3 were treated for 24 weeks with the same dose of peginterferon and ribavirin 800 mg /day. Results: Viral genotypes 1, 2, 3 and 5 were present in 81, 4, 11 and 4 percent of patients, respectively. Twenty four patients (46 percent), 18 with genotype 1, achieved a sustained viral response. Age was the only variable that infl uenced the response to treatment. Conclusions: Approximately half of the patients with chronic hepatitis C, achieve a sustained viral response with peginterferon and ribavirin.

Treatment of dairy manure effluent using freshwater algae: algal productivity and recovery of manure nutrients using pilot-scale algal turf scrubbers.

Cultivating algae on nitrogen (N) and phosphorus (P) in animal manure effluents presents an alternative to the current practice of land application. The objective of this study was to determine values for productivity, nutrient content, and nutrient recovery using filamentous green algae grown in outdoor raceways at different loading rates of raw and anaerobically digested dairy manure effluent. Algal turf scrubber raceways (30m2 each) were operated in central Maryland for approximately 270 days each year (roughly April 1-December 31) from 2003 to 2006. Algal biomass was harvested every 4-12 days from the raceways after daily additions of manure effluent corresponding to loading rates of 0.3 to 2.5g total N (TN) and 0.08 to 0.42g total P (TP) m(-2)d(-1). Mean algal productivity values increased from approximately 2.5g DW m(-2)d(-1) at the lowest loading rate (0.3g TN m(-2)d(-1)) to 25g DW m(-2)d(-1) at the highest loading rate (2.5g TN m(-2)d(-1)). Mean N and P contents in the dried biomass increased 1.5-2.0-fold with increasing loading rate up to maximums of 7% N and 1% P (dry weight basis). Although variable, algal N and P accounted for roughly 70-90% of input N and P at loading rates below 1g TN, 0.15g TP m(-2)d(-1). N and P recovery rates decreased to 50-80% at higher loading rates. There were no significant differences in algal productivity, algal N and P content, or N and P recovery values from raceways with carbon dioxide supplementation compared to values from raceways without added carbon dioxide. Projected annual operational costs are very high on a per animal basis ($780 per cow). However, within the context of reducing nutrient inputs in sensitive watersheds such as the Chesapeake Bay, projected operational costs of $11 per kgN are well below the costs cited for upgrading existing water treatment plants.

Recycling of manure nutrients: use of algal biomass from dairy manure treatment as a slow release fertilizer.

An alternative to land spreading of manure is to grow crops of algae on the N and P present in the manure and convert manure N and P into algal biomass. The objective of this study was to evaluate the fertilizer value of dried algal biomass that had been grown using anaerobically digested dairy manure. Results from a flask study using two soils amended with algal biomass showed that 3% of total algal nitrogen (N) was present as plant available N at day 0. Approximately 33% of algal N was converted to plant available N within 21 days at 25 degrees C in both soils. Levels of Mehlich-3 extractable phosphorus (P) in the two soils rose with increasing levels of algal amendment but were also influenced by existing soil P levels. Results from plant growth experiments showed that 20-day old cucumber and corn seedlings grown in algae-amended potting mix contained 15-20% of applied N, 46-60% of available N, and 38-60% of the applied P. Seedlings grown in algae-amended potting mixes were equivalent to those grown with comparable levels of fertilizer amended potting mixes with respect to seedling dry weight and nutrient content. These results suggest that dried algal biomass produced from treatment of anaerobically digested dairy manure can substitute for commercial fertilizers used for potting systems.

Treatment of dairy manure effluent using freshwater algae: elemental composition of algal biomass at different manure loading rates.

The cultivation of algae on nitrogen (N) and phosphorus (P) in animal manure effluents presents an alternative to the current practice of land application. However, the use and value of the resulting algal biomass as a feed or soil supplement depend, in part, on whether the biomass contains any harmful components such as heavy metals. The objective of this study was to determine how the elemental composition of algae changed in response to different loading rates of anaerobically digested flushed dairy manure effluent. Algal biomass was harvested weekly from laboratory-scale algal turf scrubber (ATS) units using four manure loading rates (2, 4, 6, or 9 L m(-2) day(-1)) corresponding to daily loading rates of 0.8-3.7 g of total N and 0.12-0.58 g of total P. Mean N and P contents in the dried biomass increased 1.6-1.8-fold with increasing loading rate up to maximums of 6.5% N and 0.84% P at 6 L m(-2) day(-1). Concentrations of Al, Ca, Cu, Fe, Mg, Mn, and Zn showed similar 1.4-1.8-fold increases up to maximums at a loading rate of 6 L m(-2) day(-1), followed by plateaus or decreases above this loading rate. Concentrations of Cd, Mo, and Pb initially increased with loading rate but then declined to levels comparable to those at the lowest loading rate. Concentrations of Si and K did not increase significantly with loading rate. The maximum concentrations of individual components in the algal biomass were as follows (in mg kg(-)(1)): 1100 (Al), 9700 (Ca), 0.43 (Cd), 56 (Cu), 580 (Fe), 5.0 (Pb), 2300 (Mg), 240 (Mn), 3.0 (Mo), 14,700 (K), 210 (Si), and 290 (Zn). At these concentrations, heavy metals in the algal biomass would not be expected to reduce its value as a soil or feed amendment.