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PubMed1995

Rapid electrogenic sulfate-chloride exchange mediated by chemically modified band 3 in human erythrocytes.

One of the modes of action of the red blood cell anion transport protein is the electrically silent net exchange of 1 Cl- for 1 SO4= and 1 H+. Net SO4(=)-Cl- exchange is accelerated by low pH or by conversion of the side chain of glutamate 681 into an alcohol by treatment of intact cells with Woodward's reagent K (WRK) and BH4-. The studies described here were performed to characterize the electrical properties of net SO4(=)-Cl- exchange in cells modified with WRK/BH4-. The SO4= conductance measured in 100 mM SO4= medium is smaller in modified cells than in control cells. However, the efflux of [35S] SO4= into a 150-mM KCl medium is 80-fold larger in modified cells than in control cells and is inhibited 99% by 10 microM H2DIDS. No detectable H+ flux is associated with SO4(=)-Cl- exchange in modified cells. In the presence of gramicidin to increase the cation permeability, the stoichiometry of SO4(=)-Cl- exchange is not distinguishable from 1:1. In modified cells loaded with SO4=, the valinomycin-mediated efflux of 86Rb+ into an Na-gluconate medium is immediately stimulated by the addition of 5 mM extracellular Cl-. Therefore, SO4(=)-Cl- exchange in modified cells causes an outward movement of negative charge, as expected for an obligatory 1:1 SO4(=)-Cl- exchange. This is the first example of an obligatory, electrogenic exchange process in band 3 and demonstrates that the coupling between influx and efflux does not require that the overall exchange be electrically neutral. The effects of membrane potential on SO4(=)-SO4= exchange and SO4(=)-Cl- exchange in modified cells are consistent with a model in which nearly a full net positive charge moves inward through the transmembrane field during the inward Cl- translocation event, and a small net negative charge moves with SO4= during the SO4= translocation event. This result suggests that, in normal cells, the negative charge on Glu 681 traverses most of the transmembrane electric field, accompanied by Cl- and the equivalent of two protein-bound positive charges.

Anion Exchange Protein 1, Erythrocyte↗

PubMed1989

Rapid and slow gating of veratridine-modified sodium channels in frog myelinated nerve.

The properties of voltage-dependent Na channels modified by veratridine (VTD) were studied in voltage-clamped nodes of Ranvier of the frog Rana pipiens. Two modes of gating of VTD-modified channels are described. The first, occurring on a time scale of milliseconds, is shown to be the transition of channels between a modified resting state and a modified open state. There are important qualitative and quantitative differences of this gating process in nerve compared with that in muscle (Leibowitz et al., 1986). A second gating process occurring on a time scale of seconds, was originally described as a modified activation process (Ulbricht, 1969). This process is further analyzed here, and a model is presented in which the slow process represents the gating of VTD-modified channels between open and inactivated states. An expanded model is a step in the direction of unifying the known rapid and slow physiologic processes of Na channels modified by VTD and related alkaloid neurotoxins.

Animals↗

PubMed1991

Accurate in vitro translesion synthesis by Escherichia coli DNA polymerase I (large fragment) on a site-specific, aminofluorene-modified oligonucleotide.

We have measured the accuracy of in vitro synthesis by DNA polymerase I (large fragment) during translesion synthesis past an aminofluorene (AF) adduct. These studies were carried out using a site-specifically modified template which contained a single AF adduct. The template was prepared by first modifying the lone guanine in a 17 base long oligonucleotide and extensively purifying and characterizing this product. The modified 17mer was then ligated to a synthetic duplex to produce a 31 nucleotide long template strand containing the AF adduct annealed to a 14mer, such that the 3'-hydroxyl primer terminus was four nucleotides before the modified guanine. Synthesis on this template by DNA polymerase I efficiently bypassed the AF adduct and produced full-length duplex 31mers. T7 DNA polymerase, on the other hand, was unable to utilize the AF-modified template though it was active on an identical unmodified one. The strand synthesized by DNA polymerase I was then separated from the modified strand, annealed to a complementary oligonucleotide, and the resulting heteroduplex cloned into M13. Each of the 49 clones isolated had sequences which indicated that cytidine had been incorporated opposite the AF-modified guanine.

Base Sequence↗

PubMed1982

In vitro enzymatic recognition of DNA modified by O,O'-diacetyl or O-acetyl derivatives of the carcinogen 4-hydroxyaminoquinoline-1-oxide.

Purified DNA was modified in vitro by 3H-labelled O-acetyl or O,O'-diacetyl-4-hydroxyaminoquinoline-1-oxide (Ac4HAQO or di Ac-4HAQO). It was then subjected to the action of the single-stranded DNA specific nuclease S1 and the digested fractions were analysed. For both types of modified DNA, the release of non-modified nucleotides was faster than the release of modified nucleotides. This result is at variance with that obtained with acetoxy-acetylaminofluorene-modified DNA: in the latter case, the modified nucleotides were preferentially released. The results suggest that the S1 endonuclease can recognize different conformational changes in DNA, which depend on the carcinogen used. The enzymatic activity (or activities) present in Micrococcus luteus cell extracts released ethanol-soluble products from Ac-4HAQO modified DNA.

4-Hydroxyaminoquinoline-1-oxide↗

PubMed1988

Interlaboratory comparison of antisera and immunoassays for benzo[a]pyrene-diol-epoxide-I-modified DNA.

An interlaboratory comparison of immunoassays using antisera elicited against benzo[a]pyrene-diol-epoxide-modified DNA (BPDE-I-DNA) was carried out resulting in standardization of antisera, competitors and assay conditions. The assays used included competitive enzyme-linked immunosorbent assays (ELISA) with color and fluorescence endpoint detection and an ultrasensitive enzyme radioimmunoassay (USERIA) with a radioactive endpoint. Three different antisera were compared, two of which were obtained from different rabbits immunized with the same BPDE-I-DNA and a third from an animal immunized with another BPDE-I-DNA sample. Samples of standardized BPDE-I-DNA with high (36 pmol adduct/microgram DNA; 1.2 adducts/10(2) nucleotides) and low (4.5 fmol/microgram DNA; 1.5 adducts/10(6) nucleotides) modification levels were prepared and used in each laboratory. The antisera were all elicited against DNAs modified to a high extent, and it was therefore not surprising that they detected adducts in a slightly modified DNA sample with lower efficiency than those in highly modified DNA samples. The discrepancy of antibody recognition between the highly and slightly modified samples varied between 1.4- and 11.2-fold depending on the antiserum and assay. To ascertain the quantitative capability of the immunoassays, the modification level of DNA isolated from mouse keratinocytes treated with [3H]benzo[a]pyrene was determined by radioactivity and immunoassay. These results indicated that when a biological sample is assayed against a BPDE-I-DNA standard modified in the same range as the biological samples (4.5 fmol/microgram), quantitative recovery of adducts is achieved by immunoassay. These studies resulted in the realization that interlaboratory differences in immunoassay procedure can have significant consequences for data comparison and that where possible it is preferable for laboratories to use the same antisera and modified DNA standards.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed1988

Dosage-dependent modifiers of position effect variegation in Drosophila and a mass action model that explains their effect.

Twelve dominant enhancers of position effect variegation, representing four loci on the second and third chromosomes of Drosophila melanogaster, have been induced by P-element mutagenesis. Instead of simple transposon insertions, seven of these mutations are cytologically visible duplications and three are deficiencies. The duplications define two distinct regions, each coinciding with a locus that also behaves as a dominant haplo-dependent suppressor of variegation. Conversely, two of the deficiencies overlap with a region that contains a haplo-dependent enhancer of variegation while duplications of this same region act to suppress variegation. The third deficiency defines another haplo-dependent enhancer. These data indicate that loci capable of modifying variegation do so in an antipodal fashion through changes in the wild-type gene copy number and may be divided into two reciprocally acting classes. Class I modifiers enhance variegation when duplicated or suppress variegation when deficient. Class II modifiers enhance when deficient but suppress when duplicated. From our data, and those of others, we propose that in Drosophila there are about 20 to 30 dominant loci that modify variegation. Most appear to be of the class I type whereas only two class II modifiers have been identified so far. From these observations we put forth a model, based on the law of mass action, for understanding how such suppressor-enhancer loci function. We propose that each class I modifier codes for a structural protein component of heterochromatin and their effects on variegation are a consequence of their dosage dependent influence on the extent of the assembly of heterochromatin at the chromosomal site of the position effect. It is further proposed that class II modifiers may inhibit the class I products directly, bind to hypothetical termination sites that define heterochromatin boundaries or promote euchromatin formation. Consistent with our mass action model we find that combining two enhancers together produce additive and not epistatic effects. Also, since different enhancers have different relative strengths on different variegating mutants, we suggest that heterochromatic domains are constructed by a combinatorial association of proteins. The mass action model proposed here is of general significance for any assembly driven reaction and has implications for understanding a wide variety of biological phenomena.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1984

Conformations of poly(dG-dC).poly(dG-dC) modified by the O-acetyl derivative of the carcinogen 4-hydroxyaminoquinoline 1-oxide.

Poly(dG-dC).poly(dG-dC) has been modified by reaction with 4-acetoxyaminoquinoline 1-oxide (Ac-4 HAQO), the ultimate carcinogen of 4-nitroquinoline 1-oxide. The circular dichroism (CD) spectra of the modified and unmodified polymers have been compared under various experimental conditions. The CD spectra were recorded in 1 mM phosphate, 50% (v/v) ethanol, 3.8 M LiCl and 95% (v/v) ethanol, conditions in which poly(dG-dC).poly(dG-dC) adopts the B-, Z-, C- and A-form respectively. In 1 mM phosphate buffer, poly(dG-dC).poly(dG-dC) modified by Ac-4 HAQO seems not to contain regions in the Z-form. Z-form induction could be progressively obtained by the addition of ethanol as follows: in the buffer with about 30% ethanol the modified polymer started to adopt the Z structure, while 40% of ethanol in the buffer was necessary for the unmodified polymer. In the 50% ethanol-1 mM phosphate buffer mixture (v/v), poly(dG-dC).poly(dG-dC) was entirely in the Z-form while poly(dG-dC).poly(dG-dC) modified by Ac-4 HAQO remained partially in the B-form. Enzymatic digestions with the nuclease S1 which is specific of the single-stranded DNA were carried out in order to support the modified poly(dG-dC).poly(dG-dC) CD study conclusions. The role played by the two major adducts on the conformational characteristics of modified polymer is discussed.

Aminoquinolines↗

PubMed1988

Separation of SH-modified myosin subfragment-1 (A1) isozyme into two distinct equimolar fractions by an affinity chromatography.

Our previous kinetic studies indicated that SH-modified myosin subfragment-1 A1 isozyme (S1(A1] contains at least two different types of active sites (Emoto, Y., Kawamura, T., & Tawada, K. (1985) J. Biochem. 98, 735-745). In those studies we have modified highly reactive SH-groups in S1(A1) with thimerosal. In this work, we separated the modified S1(A1) into two equimolar fractions by affinity chromatography with agarose-ADP. For the separation, Mg2+ in the elution buffer was indispensable. Although the two fractions appeared to have the same number of modified SH-groups per mol of S1, they had different enzymic and fluorescent properties. SH-modification with an excess of thimerosal for a much longer duration did not change any of the results: not the chromatographic profile, the properties of the two fractions, nor the number of modified SH-groups. Hence the two different populations were not generated by incomplete modification. After reduction with dithiothreitol, however, the differences between the two fractions disappeared. When we separately re-modified the reduced fractions and re-chromatographed them, in each case we again obtained two fractions, which had the same properties as the two fractions obtained from the original modification with thimerosal. These results demonstrate that the active site heterogeneity in SH-modified S1(A1) had no intrinsic origin in the unmodified S1: it was introduced by the SH-modification, but by an unknown mechanism(s) other than incomplete modification.

Adenosine Triphosphatases↗

PubMed1999

Use of abciximab-modified thrombelastography in patients undergoing cardiac surgery.

UNLABELLED: Thrombelastography (TEG) is a reliable coagulation monitoring system that can guide blood product transfusion in cardiac surgery. The maximum amplitude (MA) of TEG measures clot strength, which is dependent on both fibrinogen level and platelet function. Inhibition of platelet function with abciximab-fab is suggested to permit quantitative assessment of the contribution of fibrinogen to clot strength. We hypothesized that abciximab-modified TEG permits prediction of plasma fibrinogen levels and that the difference of standard MA and abciximab-modified MA (deltaMA) is a correlate for platelet function. We correlated abciximab-modified MA with plasma fibrinogen levels and deltaMA with platelet count in patients undergoing coronary revascularization. Correlation between plasma fibrinogen levels and abciximab-modified MA was significant (adjusted r2: 0.8; P < 0.0001). Correlation of deltaMA with platelet count was not significant when calculated in millimeters (adjusted r2: 0.04; P = 0.73). However, when deltaMA was calculated in dynes per square centimeter (deltaGMA), it correlated significantly with platelet count (adjusted r2: 0.51; P < 0.0001). We conclude that abciximab-modified TEG may therefore help to discriminate between hypofibrinogenemia and platelet dysfunction as a cause of decreased MA. IMPLICATIONS: We examined the use of abciximab-modified thrombelastography in patients undergoing cardiac surgery. Modification of thrombelastography with abciximab-fab allows prediction of fibrinogen levels, despite coagulation altered by cardiac surgery. The difference of standard maximum amplitude and abciximab-modified maximum amplitude correlates with platelet function when expressed in dynes per square centimeter.

Abciximab↗

PubMed1994

Oxygen Fick and modified carbon dioxide Fick cardiac outputs.

OBJECTIVE: To compare cardiac outputs estimated from the classical oxygen Fick and modified CO2 Fick methods with thermodilution cardiac output. The modified CO2 Fick cardiac output was obtained by replacing the oxygen uptake (VO2) in the Fick equation with the CO2 production (VCO2) divided by either an assumed or measured value of the respiratory exchange ratio or with an independently determined constant (Crit Care Med 1991; 19:1270-1277). DESIGN: Criterion standard study. SETTING: The medical and surgical intensive care unit (ICU) in a Veterans Affairs Medical Center. PATIENTS: A total of 17 patients (26 studies) and 11 surgical patients (13 studies), predominantly mechanically ventilated using the intermittent mandatory ventilation mode, were studied over a period of 4.3 hrs. MEASUREMENTS: A respiratory gas exchange monitor was used to measure VO2, VCO2, and respiratory exchange ratio at 3-min intervals. Calculations were performed with arterial and venous oxygen saturations measured with both a laboratory cooximeter and bedside pulse and venous reflectance oximeters. In the oxygen Fick method, cardiac output was calculated from VO2 together with arterial and venous oxygen saturations. In the modified CO2 Fick methods, cardiac output values were calculated from arterial and venous oxygen saturations with VCO2, divided by either: a) an assumed value of the respiratory exchange ratio equal to 0.8 for all patients (method 1); b) the patient's measured value of the respiratory exchange ratio (method 2); or c) a constant, determined from an initial, simultaneous measurement of thermodilution cardiac output, VCO2, and oximetry saturations. Data were examined by linear regression analysis and bias and precision calculations. MAIN RESULTS: Thermodilution cardiac output was more related to cardiac outputs calculated with the 3 modified CO2 Fick methods than to the oxygen Fick cardiac output. Thermodilution cardiac output was closely related to the modified CO2 Fick cardiac output calculated via method 3. For this method, with pulse and venous reflectance oximetry saturations, linear regression yielded an r2 = .85, a standard error of the estimate of 0.88 L/min (n = 111) and a bias and precision of 0.11 and 0.97 L/min, respectively. Thermodilution cardiac output was less closely related to oxygen Fick cardiac output, which, when calculated with pulse and venous reflectance oximetry saturations, yielded an r2 = .50, a standard error of the estimate of 1.47 L/min (n = 128), and a bias and precision of 0.01 and 1.85 L/min, respectively. CONCLUSIONS: We conclude from this study that thermodilution cardiac output is more closely related to cardiac output calculated from modified CO2 Fick methods than to oxygen Fick cardiac output. Since cardiac output calculated with the modified CO2 Fick method 3 obviates the difficulties associated with measuring VO2 accurately and requires neither an assumption of nor measurement of the respiratory exchange ratio, method 3 may prove to be clinically useful for continuous cardiac output monitoring via oximetry in ICU patients.

Adult↗

PubMed2000

Modifiable risk factors predict functional decline among older women: a prospectively validated clinical prediction tool. The Study of Osteoporotic Fractures Research Group.

OBJECTIVE: To identify modifiable predictors of functional decline among community-residing older women and to derive and validate a clinical prediction tool for functional decline based only on modifiable predictors. DESIGN: A prospective cohort study. SETTING: Four geographic areas of the United States. PARTICIPANTS: Community-residing women older than age 65 recruited from population-based listings between 1986 and 1988 (n = 6632). MEASUREMENTS: Modifiable predictors were considered to be those that a clinician seeing an older patient for the first time could reasonably expect to change over a 4-year period: benzodiazepine use, depression, low exercise level, low social functioning, body-mass index, poor visual acuity, low bone mineral density, slow gait, and weak grip. Known predictors of functional decline unlikely to be amenable to intervention included age, education, medical comorbidity, cognitive function, smoking history, and presence of previous spine fracture. All variables were measured at baseline; only modifiable predictors were candidates for the prediction tool. Functional decline was defined as loss of ability over the 4-year interval to perform one or more of five vigorous or eight basic daily activities. RESULTS: Slow gait, short-acting benzodiazepine use, depression, low exercise level, and obesity were significant modifiable predictors of functional decline in both vigorous and basic activities. Weak grip predicted functional decline in vigorous activities, whereas long-acting benzodiazepine use and poor visual acuity predicted functional decline in basic activities. A prediction rule based on these eight modifiable predictors classified women in the derivation set into three risk groups for decline in vigorous activities (12%, 25%, and 39% risk) and two risk groups for decline in basic activities (2% and 10% risk). In the validation set, the probabilities of functional decline were nearly identical. CONCLUSIONS: A substantial portion of the variation of functional decline can be attributed to risk factors amenable to intervention over the short term. Using eight modifiable predictors that can be identified in a single office visit, clinicians can identify older women at risk for functional decline.

Activities of Daily Living↗

PubMedDate not supplied

Serial subcultivation of Giardia lamblia in Keister's modified TYI-S-33 medium containing ultroser G.

The ability of Giardia strains of the duodenalis type to grow in Keister's modified TYI-S-33 medium varies with serum lot. Recently, strains of Giardia including MR4, WB, and Human-1-Portland, have been cultivated in Keister's modified TYI-S-33 medium containing the serum substitute Ultroser G and have been cultured serially as least 40 times. An optimal concentration of 8% Ultroser G promotes maximal growth in Keister's modified TYI-S-33 medium for all three strains. This concentration of Ultroser G will produce a two-log increase in the number of trophozoites in approximately three days post-inoculation. Generation times for the trophozoites ranging from 6 to 11 h have been achieved in Keister's modified TYI-S-33 containing 10% adult bovine serum and from 8 to 13 h in Keister's modified TYI-S-33 with 8% Ultroser G. Despite the excellent growth of Giardia strains in medium containing Ultroser G, the maximum trophozoite density is only about half of that achieved in Keister's modified TYI-S-33 medium supplemented with 10% adult bovine serum. Comparisons of trophozoites grown with serum or the serum substitute reveal no discernable differences in morphology and motility. Additionally, these strains have been successfully cryopreserved and revived in Keister's modified TYI-S-33 medium supplemented with Ultroser G. Because Ultroser G is a characterized mixture of six main groups of ingredients (growth factors, adhesion factors, mineral trace elements, hormones, binding proteins, and vitamins), the variability in cell proliferation that may occur when changing serum lots should be minimized when using this product.

Animals↗

PubMed1990

Identification of Salmonella somatic and flagellar antigens by modified serological methods.

This report describes two modified methods for the identification of Salmonella somatic (O) and flagellar (H) antigens. Over a period of 2 years, both modified methods were found to be approximately three times less labor intensive than the standard methods while requiring no more technical skill. The modified methods were as accurate as the standard methods in identifying the O and H antigens of 350 Salmonella isolates. Furthermore, 43 O antisera reacted exclusively with organisms possessing homologous O antigens when the modified and two standard methods were used. At the antiserum dilutions used for H antigen identification, H antisera did not react with O antigens or heterologous H antigens by either the modified or the standard method. Compared with the standard method for H antigen identification, the modified method was approximately 20 times more economical with respect to antisera and usually generated a 1.5- to 4-fold higher titer. Since the antisera stored for use in the modified method for H antigen identification were usually 100-fold more dilute than the antisera stored for the standard method, an antibody-stabilizing buffer was incorporated in the diluted antisera, allowing these reagents to be used for at least 9 to 16 months.

Agglutination Tests↗

PubMed1979

Outer membrane of Pseudomonas aeruginosa: heat- 2-mercaptoethanol-modifiable proteins.

A number of polyacrylamide gel systems and solubilization procedures were studied to define the number and nature of "major" polypeptide bands in the outer membrane of Pseudomonas aeruginosa. It was shown that five of the eight major outer membrane proteins were "heat modifiable" in that their mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was determined by the solubilization temperature. Four of these heat-modifiable proteins had characteristics similar to protein II of the Escherichia coli outer membrane. Addition of lipopolysaccharide subsequent to solubilization caused reversal of the heat modification. The other heat-modifiable protein, the porin protein F, was unusually stable to sodium dodecyl sulfate. Long periods of boiling in sodium dodecyl sulfate were required to cause conversion to the heat-modified form. This was demonstrated both with outer membrane-associated and purified lipopolysaccharide-depleted protein F. Furthermore, lipopolysaccharide treatment had no effect on the mobility of heat-modified protein F. Thus it is concluded that protein F represents a new class of heat-modifiable protein. It was further demonstrated that the electrophoretic mobility of protein F was modified by 2-mercaptoethanol and that the 2-mercaptoethanol and heat modification of mobility were independent of one another. The optimal conditions for the examination of the outer membrane proteins of P. aeruginosa by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis are discussed.

Bacterial Proteins↗

PubMed1991

A modified procedure for simultaneous extraction and subsequent assay of calcium-dependent and lysosomal protease systems from a skeletal muscle biopsy.

An extraction and assay system was developed for quantifying endogenous muscle proteases from a single 5-g sample. A single extraction buffer was developed for simultaneous extraction of both calcium-dependent proteases (CDP) and cathepsins. Protease activity determined by the modified procedure was compared to standard procedures currently used in our laboratory. The successful use of the modified procedure on muscle biopsies was verified. Activities per gram of ovine longissimus muscle of CDP system components for 50-g standard and 5-g modified procedures were not different (P greater than .05) for CDP-I (1.16 vs 1.08), CDP-II (.89 vs 1.03), or CDP inhibitor (2.34 vs 2.32), respectively. Activities of cathepsins per gram of muscle for standard and modified procedures were higher (P less than .05) for the modified procedure (cathepsins B + L, 202.0 vs 309.8), but not different (P greater than .05) for cathepsin B (76.6 vs 98.8). Cystatin-like activity was not different (P greater than .05; 3.4 vs 3.2). To test the effect of location within the longissimus muscle on protease activities, 5 g of longissimus muscle was removed immediately postmortem from each of six locations from each side of three steer carcasses. Location within the longissimus muscle had no effect (P greater than .05) on the protease activities measured. Protease activities determined on bovine longissimus muscle biopsies with the modified procedure were similar to immediate postmortem activities. These data verify that the modified procedure was as able to quantify endogenous muscle proteases as the standard procedures and could be used on muscle biopsies. This procedure should be useful in studying the role of endogenous muscle proteases in muscle growth and postmortem proteolysis.

Animals↗

PubMed1998

Evaluation of enzymatically modified potato starches in diets for weanling pigs.

We conducted three growth trials to evaluate replacing carbohydrate sources with enzymatically modified potato starches in diets for weanling pigs. In Exp. 1, 180 pigs (initially 5.3 kg and 21+/-2 d of age) were used to compare the effects of corn (36.5%), edible-grade oat flour (36.5%), two enzymatically modified potato starches (12%), and added lactose (12%) on pig performance. Potato Starch 1 had a dextrose equivalent (DE) of 6 and Potato Starch 2 had a DE of 20; both were spray-dried maltodextrans. Pigs that were fed Potato Starch 2 had greater (P<.05) ADG and ADFI than pigs fed diets that contained corn or oat flour from d 0 to 14 after weaning, and pigs fed either Potato Starch 1 or added lactose had intermediate ADG and ADFI. However, for the overall trial (d 0 to 35), no differences (P>.10) in growth performance were observed. In Exp. 2, 198 pigs (initially 4.3 kg and 19+/-2 d of age) were used to determine whether modified Potato Starch 2 could replace a portion of the corn or lactose in the diet. The control diet contained 10% dried whey, and additional treatments were formulated by adding 7 or 14% modified Potato Starch 2 or lactose in place of corn. A positive control diet was formulated containing 29% dried whey. From d 0 to 14 after weaning, increasing dietary lactose improved (linear, P<.04) ADG and ADFI. Increasing the potato starch had no effect on ADG but increased ADFI (linear, P<.02). In Exp. 3, 180 pigs (initially 3.9 kg and 14+/-3 d of age) were used to evaluate Potato Starch 2 or 3 (DE = 30, a spray-dried glucose syrup) as replacements for either corn or lactose in the diet. Pigs were fed a control diet containing 15% dried whey and 12% added lactose. Twelve percent modified Potato Starch 2 or 3 replaced either corn or lactose in the diet on a wt/wt basis. From d 0 to 14 and d 0 to 21, pigs fed either modified potato starch substituted for corn had greater (P<.07) ADG than those fed the control diet. Pigs fed diets with either modified starch substituted for lactose had similar ADG as those fed the control diet. These results suggest that when substituted for corn, Potato Starch 2 can improve growth performance of weanling pigs.

Animal Feed↗

PubMedDate not supplied

Control release of prostaglandin E2 from polylactic acid microcapsules, microparticles and modified microparticles.

Low molecular weight polylactic acid (PLA) microparticles containing prostaglandin E2 were prepared. An average particle size of 30 micron was obtained by grinding at low temperature. These particles were further treated by heating to modify the shape and the release pattern. Microscopic studies showed that the modified particles had a smoother surface than the non-modified particles. The drug was also incorporated into PLA microcapsules using the solvent evaporation process, but the incorporation efficiency was lower. We studied the release profiles of modified particles prepared using different molecular weight PLA. The release rate depended on the molecular weight with lower molecular weights having a greater release rate. In addition, the release studies showed different matrix forms made from the same molecular weight PLA had different release patterns. For example, the microcapsules released the drug very slowly whereas the modified particles exhibited a moderate release rate. It was also noted that the matrix release model could describe the release patterns of microcapsules and modified particles very well. However, the release patterns of non-modified microparticles did not follow this model.

Capsules↗

PubMed1993

The role of biological response modifiers in disease control.

Immune responses to infectious agents involve a complex set of interactions between cells and the factors they produce that culminate with disease resolution or death. Therefore, the manipulation of the immune system may have a great impact on the preservation and restoration of animal health. Biological response modifiers are agents that modify the host's response to pathogens with resultant beneficial prophylactic or therapeutic effects. The best known example of biological response modifiers are vaccines, by which administration of a nonpathogenic form of a microorganism prepares the immune system to produce a more effective response upon subsequent infection with the pathogenic form. Nevertheless, the use of biological response modifiers other than vaccines that enhance the immune response is now the focus of many investigations. In this review, a brief overview of the immune system is presented, and special emphasis is placed on possible areas of intervention with biological response modifiers and a description of the prophylactic and therapeutic potential of biological response modifiers. Specific examples are presented to demonstrate examples of disease modification by biological response modifiers through stimulation of nonspecific and antigen specific immunities.

Animals↗