Hydrolysis and acidification of grass silage in leaching bed reactors.

Hydrolysis and acidification of grass silage (GS) was examined in leaching bed reactors (LBRs) under organic loading rates (OLRs) of 0.5, 0.8 and 1.0 kg volatile solids (VS)/m(3)/day. The LBRs were run in duplicate over five consecutive batch tests (Batch tests 1-5) to examine the effects of pH, leachate dilution and addition of inoculum on the process of hydrolysis and acidification. The highest GS hydrolysis yields of 52-58%, acidification yields of 57-60% and VS removals of 62-66% were obtained in Batch test 4. Increasing OLRs affected the hydrolysis yield negatively. In Batch test 4, the reduction of lignocellulosic materials was up to 74.4% of hemicellulose, 30.1% of cellulose and 9.3% of lignin within 32 days. Cellulase activity can be used as an indicator for the hydrolysis process. Methane production from the LBRs only accounted for 10.0-13.8% of the biological methane potential of GS.

Methane production from anaerobic co-digestion of the separated solid fraction of pig manure with dried grass silage.

Anaerobic co-digestion of the solid fraction of separated pig manure (SPM) with dried grass silage (DGS) was evaluated in three identical continuously stirred tank reactors (CSTRs) at 35±1 °C. The feedstock contained 20% DGS in CSTR1, 30% DGS in CSTR2 and 40% DGS in CSTR3 on a volatile solids (VS) basis. Organic loading rates (OLR) of 1.0, 1.5, 2.0 and 3.0 kg VS/m(3)/d were studied and it was found that the OLR affected the digester performance more than the DGS proportion in the feedstock. Tripling the OLR increased volumetric methane yields by 88% and decreased specific methane yields by 38%. At the OLR of 3 kg VS/m(3)/d, post-methane production potentials of digestates ranged from 38% to 41% of total methane production potentials of the feedstock. An energy yield estimation on a 654-sow pig unit showed that 268-371 MWh/a electricity and 383-530 MWh/a heat would be generated.

Effects of thermo-chemical pre-treatment of grass silage on methane production by anaerobic digestion.

Dried grass silage (GS) was pre-treated at different NaOH loading rates (1%, 2.5%, 5% and 7.5% by volatile solids (VS) mass in grass silage) and temperatures (20 °C, 60 °C, 100 °C and 150 °C) to determine effects on its bio-degradability in terms of the hydrolysis yield and degradation of ligno-cellulosic materials for biogas production. At 100 °C and the four NaOH loadings, up to 45% of the total COD was solubilised and up to 65.6%, 36.1% and 21.2% of lignin, hemicellulose and cellulose were removed, respectively; biological methane production potentials obtained were 359.5, 401.8, 449.5 and 452.5 ml CH4/g VS added, respectively, being improved by 10-38.9% in comparison with untreated GS. VS removals following anaerobic digestion were 67.6%, 76.9%, 85.3%, 95.2% and 96.7% for untreated GS and GS treated at the four NaOH loadings, respectively. 100 °C and the NaOH loading rate of 5% is recommended as a proper GS pre-treatment condition.

Effect of pig manure to grass silage ratio on methane production in batch anaerobic co-digestion of concentrated pig manure and grass silage.

Anaerobic co-digestion of concentrated pig manure (PM) with grass silage (GS) at five different PM to GS volatile solid (VS) ratios of 1:0, 3:1, 1:1, 1:3 and 0:1 was evaluated by examining operation stability and methane (CH(4)) production potentials. The highest specific CH(4) yields were 304.2 and 302.8 ml CH(4)/g VS at PM to GS ratios of 3:1 and 1:1, respectively. The digestion systems failed at the ratio of 0:1. The lag phase lasted 29.5, 28.1, 24.6 and 21.3 days at the ratios of 1:0, 3:1, 1:1 and 1:3, respectively. The daily methane yield was linearly correlated with the acetic acid concentration, indicating methane production was probably associated with acetoclastic methanogenesis. The hydrolysis constant linearly decreased with increasing the fraction of GS in the feedstock. This study recommends applying the PM to GS ratio of 1:1 in practice due to a high specific methane yield and a short lag phase.

Prediction of nitrogen excretion in feces and urine of beef cattle offered diets containing grass silage.

Data from 286 beef cattle, obtained in total diet digestibility assessments, were used to examine effects of dietary and animal factors on N excretion in feces and urine and to develop prediction equations for N excretion in beef cattle. The animals used were mainly from beef breeds, at various ages (from growth to finishing) and live BW (153 to 580 kg), and offered diets containing grass silage at production feeding levels. Dietary forage proportion ranged from 199 to 1,000 g/kg of DM and dietary CP concentration from 108 to 217 g/kg of DM. Linear and multiple regression techniques were used to examine relationships between the efficiency of N utilization and dietary and animal variables with the experimental effects removed. The statistical analysis indicated that N excretion was related positively (P < 0.001) to live BW and intakes of DM, N, and ME, and negatively (P < 0.001) to dietary forage proportion. The prediction equation for N excretion, developed using N intake alone, produced a large r2 (0.898) and a small SE (12.3). Addition of live BW and forage proportion as supporting predictors to this relationship only marginally increased R2 to 0.915 and reduced SE to 11.2. Nitrogen excretion was less well related to live BW (r2 = 0.771, SE = 18.5) than to N intake. Addition of N intake as a proportion of DMI or ME intake to the relationship between live BW and N excretion increased R2 to 0.824 and reduced SE to 16.2. The internal validation of these equations revealed that using N intake as the primary predictor produced a very accurate prediction of N excretion. In situations where data on N intake are not available, prediction equations based on live BW and dietary N concentration together can produce a relatively accurate assessment of N excretion. A number of mitigation strategies to reduce N excretion in feces and urine in beef cattle are discussed, including manipulation of dietary N concentration, diet quality, and level of feeding. The prediction equations and mitigation strategies developed in the current study provide an approach for beef producers to quantify N excretion against production and to develop their own mitigation strategies to reduce N excretion.

Relationships among manure nitrogen output and dietary and animal factors in lactating dairy cows.

A large data set derived from total diet digestibility assessments on lactating dairy cows (535 Holstein-Friesian and 29 Norwegian) was used to examine effects of dietary and animal factors on manure (feces and urine) nitrogen (N) output and to develop mitigation strategies and prediction equations for manure N output in lactating dairy cows. Manure N output was positively and significantly related to live weight, milk yield, dietary crude protein (CP) concentration, dry matter intake, and N intake. Reducing the dietary CP concentration or increasing the milk yield decreased manure N output per kilogram of milk yield. Prediction equations for manure N output using live weight and milk yield, either alone or combined, had relatively low R2 (0.227 to 0.474) and large standard error (70.6 to 85.6) values. Addition of dietary CP concentration to these relationships considerably increased R2 to 0.754 and reduced the standard error to 48.2. Relating manure N output to N intake produced a very high r2 (0.901) and a very low standard error (30.6). The addition of live weight and milk yield to this relationship as supporting predictors only marginally increased R2 to 0.910 and reduced the standard error to 29.3. The internal validation of these equations revealed that use of N intake as the primary predictor produced a very accurate prediction of manure N output. In situations in which data on N intake are not available, prediction equations based on dietary CP concentration, live weight, and milk yield together can produce a relatively accurate assessment of manure N output.

Survival of pathogenic bacteria during mesophilic anaerobic digestion of animal waste.

The survival of pathogenic bacteria was investigated during the operation of a full-scale anaerobic digester which was fed daily and operated at 28 degrees C. The digester had a mean hydraulic retention time of 24 d. The viable numbers of Escherichia coli, Salmonella typhimurium, Yersinia enterocolitica, Listeria monocytogenes and Campylobacter jejuni were reduced during mesophilic anaerobic digestion. Escherichia coli had the smallest mean viable numbers at each stage of the digestion process. Its mean T90 value was 76.9 d. Yersinia enterocolitica was the least resistant to the anaerobic digester environment; its mean T90 value was 18.2 d. Campylobacter jejuni was the most resistant bacterium; its mean T90 value was 438.6 d. Regression analysis showed that there were no direct relationships between the slurry input and performance of the digester and the decline of pathogen numbers during the 140 d experimental period.

Regulation of granulosa cell proliferation: facilitative roles of platelet-derived growth factor and low density lipoprotein.

Recent studies suggest that epidermal growth factor (EGF) and/or transforming growth factor-alpha (TGF-alpha) and insulin-like growth factor-I (IGF-I) act synergistically to promote granulosa cell proliferation in vitro suggesting a similar role in vivo. Using a serum-restricted, monolayer culture system containing very low levels of platelet-poor plasma-derived serum (PPPDS), the facilitative roles of platelet-derived growth factor (PDGF) and low density lipoprotein (LDL) with respect to growth factor-stimulated granulosa cell proliferation were investigated. In nutrient medium containing only 0.1% PPPDS, PDGF (1-25 ng/ml) had no effect upon granulosa cell proliferation. When combined with EGF, which alone does not stimulate granulosa cell proliferation, PDGF dose-dependently increased cell proliferation to levels obtained with 10% fetal calf serum (2.4-fold increase relative to controls, P less than 0.05). When combined with EGF and IGF-I, a combination which does stimulate mitosis in granulosa cells, PDGF again dose-dependently enhanced proliferation (P less than 0.05). The extent of proliferation obtained with EGF + IGF-I + PDGF was consistently greater than that obtained with 10% fetal calf serum (P less than 0.05) but significantly less than that obtained with EGF + fetal calf serum, a treatment which stimulates rapid granulosa cell proliferation. LDL has been shown to greatly enhance granulosa cell steroidogenesis by providing exogenous cholesterol. However, cholesterol is also required for plasma membrane biosynthesis and cell growth. LDL alone, had no effect upon porcine granulosa cell proliferation relative to media controls (0.1% PPPDS) nor did it synergize with any single growth factor to induce mitosis. When combined with EGF + IGF-I, and EGF + PDGF, but not PDGF + IGF-I, LDL dose-dependently (1-25 micrograms/ml) enhanced proliferation (P less than 0.05) to levels equivalent to that obtained with 10% fetal calf serum. When combined with EGF, IGF-I, and PDGF, LDL at 10 micrograms/ml enhanced proliferation to an extent equivalent with EGF + fetal calf serum (a 5.4-fold increase relative to media controls). High density lipoprotein did not itself stimulate proliferation nor did it facilitate proliferation mediated by growth factors. When maintained in medium alone (0.1% PPPDS), the cell population doubling time was 8.0 +/- 0.5 days. In the presence of EGF, IGF-I, PDGF, and LDL (10, 10, and 5 ng/ml, and 10 micrograms/ml, respectively) the doubling time was reduced to 2.0 +/- 0.1 days.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential effects of epidermal growth factor, somatomedin-C/insulin-like growth factor I, and transforming growth factor-beta on porcine granulosa cell deoxyribonucleic acid synthesis and cell proliferation.

Recent studies have suggested that the mammalian ovary synthesizes epidermal growth factor (EGF), somatomedin-C/insulin-like growth factor I (Sm-C), and transforming growth factor-beta (TGFb) and that these growth factors may in part form a basis for intraovarian regulation of granulosa cell proliferation and differentiation. The studies described herein were initiated to determine to what extent EGF, Sm-C, and TGFb function to regulate DNA synthesis and granulosa cell proliferation during primary monolayer culture. EGF, but neither Sm-C nor TGFb, alone consistently stimulated, in a dose-dependent manner, [3H]thymidine incorporation by porcine granulosa cells under defined conditions (P less than 0.01). Sm-C (10 ng/ml) and TGFb (1 ng/ml) both enhanced EGF-stimulated [3H]thymidine incorporation (56% and 300%, respectively; P less than 0.05). The levels of incorporation obtained with EGF plus TGFb were equal to or greater than those obtained using fetal bovine serum alone. When EGF, Sm-C, and TGFb were combined, [3H]thymidine incorporation was equivalent to that obtained with EGF plus 10% fetal bovine serum, heretofore the most potent stimulatory combination for [3H]thymidine incorporation. Thus, under defined conditions, EGF, Sm-C, and TGFb act synergistically to promote DNA synthesis in primary cultures of porcine granulosa cells. Although DNA synthesis is a requisite step for but is not an accurate measurement of cell proliferation per se, we investigated whether the observed effects of EGF, Sm-C, and TGFb on DNA synthesis were realized in terms of actual cell proliferation. This was accomplished using platelet-poor plasma-derived serum (PPPDS; 0.1-2.5%), which contains reduced levels of endogenous growth factors but not components needed for cell attachment. EGF (P less than 0.05), but neither Sm-C nor TGFb, alone consistently stimulated, in a dose-dependent manner, granulosa cell proliferation, an effect directly related to the PPPDS concentration. Sm-C consistently and significantly (P less than 0.05) enhanced EGF-stimulated cell proliferation in a dose-dependent manner. The facilitative effect of Sm-C was inversely related to the PPPDS concentration, ranging from a 76 +/- 15% increase at 0.1% PPPDS to a 14% increase at 1.0% PPPDS. TGFb exhibited a bifunctional effect on granulosa cell proliferation. At low levels of PPPDS (0.1% and 0.25%) and in the absence of Sm-C, TGFb enhanced EGF-stimulated cell division, an effect which, although small and variable (24 +/- 16%), was consistent.(ABSTRACT TRUNCATED AT 400 WORDS)

All human monocytes have the capability of expressing HLA-DQ and HLA-DP molecules upon stimulation with interferon-gamma.

We have simultaneously studied expression of all three classes of human Ia (HLA-DR, DP, and DQ) on normal human B cells and monocytes (M phi) by using two-color immunofluorescence and flow cytometry. Expression was investigated on freshly isolated cells and after incubation of cells for 48 and 96 hr in interferon-gamma (IFN-gamma). All freshly isolated B cells express high levels of DR, DQ, and DP, and these levels are unchanged by incubation with IFN-gamma for 48 hr and 96 hr. In contrast, freshly isolated M phi are on the average 91% DR+, 32% DQ+, and 15% DP+. Incubation with IFN-gamma increases Ia expression on M phi to 98% DR+, 75% DQ+, and 58% DP+ at 48 hr, with virtually all cells becoming positive for all three Ia antigens at 96 hr. Furthermore, after the 96-hr incubation, antigen density increases 10-fold for DR, 15-fold for DQ, and 15-fold for DP in M phi to reach levels of expression comparable with B cells. These studies demonstrate that all peripheral blood monocytes have the capacity to become HLA-DQ and HLA-DP positive; IFN-gamma regulates expression of all three classes of human Ia in M phi; and IFN-gamma does not significantly modulate Ia expression in B cells.

Gamma interferon and 5-azacytidine cause transcriptional elevation of class I major histocompatibility complex gene expression in K562 leukemia cells in the absence of differentiation.

We studied the effects of gamma interferon (IFN-gamma) on HLA class I gene expression, differentiation, and proliferative capacity of K562 human leukemia cells. In the uninduced state, K562 cells show little or no class I gene expression but actively express the erythroid-specific gamma-globin gene as well as genes associated with cell proliferation, including the transferrin receptor, c-myc, and alpha-actin genes At both the surface protein and mRNA levels, IFN-gamma induces class I and beta 2-microglobulin gene expression, but does not alter the expression of the gamma-globin, transferrin receptor, c-myc, or alpha-actin genes. A 10-fold maximal induction of both class I surface protein and mRNA occurs at 48 h and is reversible upon withdrawal of IFN-gamma from the culture medium. In vitro nuclear run-on transcription assays were performed to directly establish that IFN-gamma exerts an early effect at the level of transcription, with maximal transcription rates occurring within 4 h. The difference between the time course of transcription induction and that of mRNA accumulation suggests that the regulation of class I gene expression in this human leukemic cell line also involves posttranscriptional mechanisms. Measurements of cell proliferation rates and cell cycle distribution, as well as the reversibility of the effects of IFN-gamma, demonstrate that the selective induction of class I genes in these cells occurs in the absence of differentiation.

Cerebral palsy: a podiatric overview.

Cerebral palsy is a nonprogressive neurologic lesion occurring during gestation or at birth with resultant motor deficit. It can be classified anatomically, according to the cerebral lesion, or functionally. In order to reach a diagnosis, and subsequently determine the correct treatment, a thorough evaluation of the patient must be performed including muscle testing, persistence of pathologic reflexes, and presence of infantile automatisms. The most frequently seen deformities of the lower extremity are equinus, equinovalgus, and equinovarus. The underlying goal of treatment is to stabilize the lower extremity and allow the patient to ambulate as independently as possible. The basic approach to therapy is conservative, but surgery, utilizing both osseous and soft tissue procedures, may be indicated to increase the efficiency of ambulation.