Search

Transition heifers face multiple stressors during the periparturient period, including first exposure to milking, that may adversely impact dry matter intake (DMI), reduce milk production, compromise immune function, and increase susceptibility to disease. It was hypothesized that reducing the combined stressors experienced at calving would improve the periparturient performance, health, and well-being of heifers. The objective of this study was to determine the effect of initiating the milking procedure 3 wk before expected calving on production, DMI, body weight, energy balance, udder health, calving traits, and health status, as indicated by plasma acute phase protein concentrations. Twenty-two primigravid heifers, blocked by expected calving date, were assigned randomly either to a prepartum milking (PM) group or control group. The PM heifers were milked twice daily beginning at 21 d before expected calving, and control heifers were not milked until after calving. All heifers had access to the same precalving and postcalving diets. Results indicated that PM heifers produced more milk during the first 2 wk after calving and had greater DMI as a percentage of body weight during the first month after calving than did control heifers, although energy balance was more negative for PM heifers. The PM heifers had reduced somatic cell counts through the first month after calving and lower average somatic cell scores during lactation despite having more quarters with mastitis infection at calving. The PM heifers had less udder edema at the third milking postcalving, and had reduced concentrations of haptoglobin in blood sooner than did control heifers. These results indicate that prepartum milking is an alternative management practice that has beneficial effects on the production, health, and well-being of first-lactation cows. [ABSTRACT FROM AUTHOR]

Our objective was to evaluate the effects of speciflc plant botanicals on performance of lactating dairy cows in commercial settings under different management and forage conditions. Holstein cows (n = 173) were allotted to treatment in a completely randomized design on four herds in Pennsylvania and were fed standard lactation diets for 30 days before treatments were applied. Cows were housed in tie stalls and fed individually. The standard lactation diet served as the control (CTL), while the treatment diet (TRT) had an additional 56 g/cow/d of a speciflc blend of botanicals (RumeNext D™; ADM Alliance Nutrition, Inc., Quincy, IL). The TRT was fed for 60 days. Individual parameters for intake and production produced grouped means from repeated measures. Milk yield improved by 1.2 kg/d (P<0.5) for TRT. There were trends (P<0.13) for decreased milk fat and protein content when TRT was fed. However, milk fat (P<0.30) and protein (P<0.10) yield tended to increase because of increased milk yield. On a farm-speciflc basis, Farm C had a decrease (P<0.05) in milk fat content, but there tended to be increases (P<0.15) in total milk and milk protein yields for TRT. There were positive responses (P<0.10) to TRT for milk, fat-corrected milk and fat yield at Farm D, as well as a tendency (P<0.11) for increased protein yield. Both Farms A and B recorded numeric performance beneflts for TRT. Results indicate that there may be farm-speciflc interactions with plant botanicals including management, basal diet, or production level. Plant botanicals may beneflt performance of lactating cattle through a potential increase in milk and fat yield. [ABSTRACT FROM AUTHOR]

Our objective was to examine the effect of speciflc plant botanicals on performance of lactating dairy cattle. Holstein cows (n=260) were divided into three groups balanced upon parity, stage of lactation (DIM), and mean milk production measured one week before the co-variant adjustment period. A 1-week, co-variant adjustment period was followed by a 42-day study. The standard lactation diet served as the control ration (CTL). Treatment diet was supplemented to provide 28 g/cow/d (LO) or 56 g/cow/d (HI) of plant botanicals (RumeNext D™; ADM Alliance Nutrition, Inc., Quincy, IL) to deliver 250 and 500 mg/d, respectively, of the active botanical components. Individual data was collected for milk production on a daily basis and milk composition on a weekly basis, while group DMI was calculated daily. Data was analyzed using the Proc Mixed procedure of SAS for a repeated measures, completely randomized design. There was no effect of treatment on milk protein content, milk yield or SCC. Milk urea nitrogen linearly decreased with treatment (P<0.05). There was an increase (P<0.05) in milk fat content for LO (3.20%, 3.33% for CTL and LO respectively) and a tendency (P<0.06) for increased fat yield (1277, 1328 g/d for CTL and LO, respectively). Feeding HI decreased (P<0.01) dry matter intake (23.5, 23.2 kg/d for CT and HI, respectively) and fat yield (1277, 1218 g/d for CT and HI, respectively; P<0.01). Milk fat yield decreased (P<0.01) by 110 g/d, which is indicative of the 1.9 kg/d decrease (P<0.01) in FCM yield for HI compared to LO. Additionally, HI cows consumed 0.2 kg/d less DM than LO (P<0.01). Plant botanicals improved animal performance at the LO feeding rate, but had negative effects at the HI rate. The negative effect of HI appeared related to intake. These results suggest feeding recommendations be based at 28 g/d to supply 250 mg/d of active botanical components. [ABSTRACT FROM AUTHOR]

Our objective was to examine if Biuret (ADM Alliance Nutrition, Inc., Quincy, IL) is a suitable replacement for ruminally degradable true protein in dairy lactation diets. Lactating Holstein cows (n=237) were divided into three groups balanced based upon parity, stage of lactation (DIM), and mean milk production measured one week before the co-variant adjustment period. The standard lactation ration served as the control ration (CT). A 2-week co-variant adjustment period in which CT was fed was followed by a 28-day test period during which cows received diets containing 0, 45 (LO), or 77 (HI) g/cow/day of Biuret. Biuret replaced an equivalent amount of soybean meal-nitrogen in the diet. Urea and total crude protein of diets were similar among diets. Estimated bypass protein content of diets decreased and non-fiber carbohydrate increased with addition of Biuret. Data was analyzed using the Proc Mixed procedure of SAS for a repeated measures, completely randomized design. Milk yield and components were covariant adjusted using data collected in the pre-test period. Substitution of Biuret for ruminally degradable true protein did not affect milk yield (P>0.10). Dry matter intake linearly decreased (P<0.05) with Biuret feeding. Efficiency of milk yield (milk/feed DMI) improved when Biuret was fed. The HI treatment decreased (P<0.05) daily milk fat yield (1371, 1374, 1305 g for CT, LO and HI, respectively) and decreased (P<0.05) milk lactose percentage (4.86%, 4.85%, 4.82% for CT, LO and HI, respectively). Data were parsed into high and low production groups based on pre-study median performance to examine treatment effects of Biuret on milk yield and composition. Milk composition of lower-producing cows was affected by Biuret whereas milk yield was more responsive to Biuret in higher-producing cows. For all cows, MUN levels increased with Biuret feeding. Milk urea nitrogen may be an appropriate tracking variable to evaluate efficiency of nitrogen use when slowly degradable NPN sources, such as Biuret, are fed to lactating dairy cows. In lactating cow diets balanced for RDP and RUP, Biuret was an effective substitute for ruminally degradable true protein. [ABSTRACT FROM AUTHOR]

An in vitro model has been developed for analyzing the two developmental phases of human dendritic cell (DC) migration. Employing the age of the culture and the addition of GM-CSF, IL-4, and serum to regulate cellular phenotype, and glass coated with acid-precipitated human plasma proteins to facilitate persistent DC translocation, the model produces three sequential in vitro phenotypes with the following suggested in vivo counterparts: (1) DCs recently isolated from blood, which are highly polar and motile, and reflect the behavior of "undifferentiated" DCs that must extravasate from the blood stream and migrate into peripheral tissue; (2) large, nonmotile, stellate DCs, which reflect the highly "differentiated" signature phenotype of DCs in peripheral tissue, whose function is to capture foreign antigens; and (3) the large, motile "dedifferentiated" DCs, which reflect the behavior of "veiled cells" that have captured an antigen, retracted dendritic processes, migrated out of peripheral tissue, and are in the process of transporting a captured antigen to a proximal draining lymph node for presentation to T cells. Computer-assisted motion analysis of the three sequential phenotypes and fluorescent staining of F-actin reveal three unique behavioral states and unique cellular architecture consistent with inferred in vivo function. This in vitro model should serve as a starting point for elucidating the cues and molecular mechanisms involved in the regulation of DC differentiation and motility., (Copyright 2000 Wiley-Liss, Inc.)

This paper is the first in a series aimed at understanding the role of beta-catenin in epithelial-mesenchymal transformation (EMT) and acquisition of mesenchymal invasive motility. Here, we compare the expression of this and related molecules in the two major tissue phenotypes, epithelial and mesenchymal, the latter including normal avian and mammalian fibroblasts and malignant human uveal melanoma cells. Previously, it was proposed that src initiates EMT by tyrosine phosphorylation of the cadherin/catenin complex resulting in a negative effect on epithelial gene expression. On the contrary, we found that although beta-catenin becomes diffuse in the cytoplasm during embryonic EMT, the cytoplasmic beta-catenin of the embryonic and adult mesenchymal cells we examined is not tyrosine phosphorylated. Pervanadate experiments indicate that cytoplasmic PTPases maintain this dephosphorylation. GSK-3beta is present, but little or no APC occurs in normal and neoplastic mesenchymal cells. The function of the nonphosphorylated cytoplasmic beta-catenin in mesenchyme may be related to invasive motility. Indeed, in order to invade extracellular matrix, transitional (Mel 252) melanoma cells transform from an epithelial to a mesenchymal phenotype with increased cytoplasmic beta-catenin. Moreover, antisense beta-catenin and plakoglobin ODNs inhibit Mel 252 and corneal fibroblast invasion of collagen. All fibroblastic, transitional, and spindle melanoma cells contain nuclear as well as cytoplasmic beta-catenin, but they are not significantly more invasive than normal fibroblasts that contain only cytoplasmic beta-catenin., (Copyright 1998 Academic Press.)

Dystroglycan is a central component of the dystrophin-glycoprotein complex (DGC), a protein assembly that plays a critical role in a variety of muscular dystrophies. In order to better understand the function of dystroglycan in development and disease, we have generated a null allele of dystroglycan (Dag1neo2) in mice. Heterozygous Dag1neo2 mice are viable and fertile. In contrast, homozygous Dag1neo2 embryos exhibit gross developmental abnormalities beginning around 6.5 days of gestation. Analysis of the mutant phenotype indicates that an early defect in the development of homozygous Dag1neo2 embryos is a disruption of Reichert's membrane, an extra-embryonic basement membrane. Consistent with the functional defects observed in Reichert's membrane, dystroglycan protein is localized in apposition to this structure in normal egg cylinder stage embryos. We also show that the localization of two critical structural elements of Reichert's membrane--laminin and collagen IV--are specifically disrupted in the homozygous Dag1neo2 embryos. Taken together, the data indicate that dystroglycan is required for the development of Reichert's membrane. Furthermore, these results suggest that disruption of basement membrane organization might be a common feature of muscular dystrophies linked to the DGC.

Choroidal and ciliary body melanomas disseminate exclusively by a hematogenous route because there are no lymphatics inside the eye. Although angiogenesis is an absolute precondition for metastasis in this tumor system, not all morphologic expressions of tumor angiogenesis are associated with metastasis from choroidal and ciliary body melanomas. Specifically, the remodeling of the microcirculation to form vascular networks is very strongly associated with metastasis. Type VI collagen is upregulated in tissue remodeling and the generation of tissue patterns and is either not present in the normal choroid or present at very low levels. This study was designed to investigate the possible expression of type VI collagen in the stroma of choroidal and ciliary body melanomas. Type VI collagen was detected in tissue sections from five primary choroidal melanomas and three melanomas involving the choroid and ciliary body in the subendothelial compartment of the microcirculation and in avascular areas by immunohistochemistry. Melanoma cell lines were established from each of these tumors. Cultured melanoma cells invaded into type I collagen gels and expressed type VI collagen by immunohistochemistry. Using specific primers for human type VI collagen, the expected band size (413 base pairs) was isolated from one of the cell lines by reverse transcriptase PCR. The presence of type VI collagen in the melanoma tumor stroma reflects active remodeling of the uveal extracellular matrix microenvironment by the melanoma cells themselves. Before the formation of the microvasculature, the expression of type VI collagen and of the other matrix components, such as hyaluronan, to which it binds, may erect a scaffold permitting the formation of higher order stromal patterns such as vascular networks. These stromal patterns, which are markers of tumor progression, may be detectable clinically by a specialized form of ultrasonography that detects backscatterers of the same dimension as tissue compartments encircled by vascular loops in networks.

We present new evidence of the temporal and spatial expression of type II collagen in the embryonic chick heart during the very early stages of its development. In particular, we emphasize the distribution of its mRNA and protein during valve formation. Type II collagen as well as several other fibrillar collagens (types I, III, and V) are present in stage 18 endocardial cushion mesenchymal cells. At stage 23, alpha 1 (II) collagen transcripts and the cognate polypeptide colocalize in the atrioventricular valves. As development proceeds, the relative abundance of alpha 1 (II) collagen transcripts decreases during the stages studied (stages 22 to 45; day 3.5 to day 19) as assayed by RNA blotting of extracts of whole hearts. Type II collagen protein was immunologically undetectable in stage 38 (day 12) hearts, although collagens I, III, and V persisted and localize in the valve regions, in the endothelial lining of the heart, and in the epicardium. In keeping with other observations of type II collagen expression in non-chondrogenic regions of a variety of vertebrate embryos, the avian heart also exhibits transient type II collagen expression.

Chick embryo myoblasts were fused in suspension culture to form myoballs by modification of previous procedures that excluded the use of divalent ion chelators and antimitotic drugs and included the continuous presence of serum in order to analyze the organized appearance and synthesis of major cytoskeletal proteins during cell attachment and spreading. The organization of the major cytoskeletal proteins actin, tubulin, and vimentin was assessed by fluorescence microscopy under these conditions as well as under conditions in which the myoballs were allowed to attach and spread on a collagen-coated substrate. Actin, detected by fluorescence microscopy, stained myoballs diffusely and was reorganized to form stress fibers in the attached and spreading myoball. Nuclei were segregated to a centrally located lattice of microtubules. The microtubule-specific drugs nocodazole and taxol prevented myoball spreading and the establishment of myotube polarity, respectively. Vimentin appeared as wavy ribbons in a perinuclear position around attached and spreading myoballs. In parallel studies, the synthesis of these cytoskeletal proteins was analyzed by radioisotopic labeling and polyacrylamide gel electrophoresis. These studies showed that myoballs possess altered ratios of actin and tubulin isoforms and of phosphorylated and nonphosphorylated vimentin compared to myotubes. These ratios rapidly change to the myotube pattern when myoballs are allowed to attach to solid substrata. Thus, although both myoballs and myotubes undergo muscle-specific differentiation, their cytoskeletal proteins are morphologically and biochemically distinct.