Biomedical subjects

R W Harvey

Publications and source records attributed to R W Harvey.

At least 19 recordsLinked to original sources

PubMed2005

Effect of ferric oxyhydroxide grain coatings on the transport of bacteriophage PRD1 and Cryptosporidium parvum oocysts in saturated porous media.

To test the effect of geochemical heterogeneity on microorganism transport in saturated porous media, we measured the removal of two microorganisms, the bacteriophage PRD1 and oocysts of the protozoan parasite Cryptosporidium parvum, in flow-through columns of quartz sand coated by different amounts of a ferric oxyhydroxide. The experiments were conducted over ranges of ferric oxyhydroxide coating fraction of lambda = 0-0.12 for PRD1 and from lambda = 0-0.32 for the oocysts at pH 5.6-5.8 and 10(-4) M ionic strength. To determine the effect of pH on the transport of the oocysts, experiments were also conducted over a pH range of 5.7-10.0 at a coating fraction of lambda = 0.04. Collision (attachment) efficiencies increased as the fraction of ferric oxyhydroxide coated quartz sand increased, from alpha = 0.0071 to 0.13 over lambda = 0-0.12 for PRD1 and from alpha = 0.059 to 0.75 over lambda = 0-0.32 for the oocysts. Increasing the pH from 5.7 to 10.0 resulted in a decrease in the oocyst collision efficiency as the pH exceeded the expected point of zero charge of the ferric oxyhydroxide coatings. The collision efficiencies correlated very well with the fraction of quartz sand coated by the ferric oxyhydroxide for PRD1 but not as well for the oocysts.

Animals↗

PubMed2003

Observation of velocity-independent electron transport in the reversed field pinch.

Confinement of runaway electrons has been observed for the first time in a reversed field pinch during improved-confinement plasmas in the Madison Symmetric Torus. Energy-resolved hard-x-ray flux measurements have been used to determine the velocity dependence of the electron diffusion coefficient, utilizing computational solutions of the Fokker-Planck transport equation. With improved-confinement, the fast electron diffusivity drops by 2 orders of magnitude and is independent of velocity. This suggests a change in the transport mechanism away from stochastic magnetic field diffusion.

Journal Article↗

PubMed2003

Sheared poloidal flow driven by mode conversion in tokamak plasmas.

A two-dimensional integral full-wave model is used to calculate poloidal forces driven by mode conversion in tokamak plasmas. In the presence of a poloidal magnetic field, mode conversion near the ion-ion hybrid resonance is dominated by a transition from the fast magnetosonic wave to the slow ion cyclotron wave. The poloidal field generates strong variations in the parallel wave spectrum that cause wave damping in a narrow layer near the mode conversion surface. The resulting poloidal forces in this layer drive sheared poloidal flows comparable to those in direct launch ion Bernstein wave experiments.

Journal Article↗

PubMed2002

Radial transport and electron-cyclotron-current drive in the TCV and DIII-D tokamaks.

Calculation of electron-cyclotron-current drive (ECCD) with the comprehensive CQL3D Fokker-Planck code for a TCV tokamak shot gives 550 kA of driven toroidal current, in marked disagreement with the 100-kA experimental value. Published ECCD efficiencies calculated with CQL3D in the much larger, higher-confinement DIII-D tokamak are in excellent agreement with experiment. The disagreement is resolved by including in the calculations electrostatic-type radial transport at levels given by global energy confinement in tokamaks. The radial transport of energy and toroidal current are in agreement.

Journal Article↗

PubMed1998

Size-selective predation on groundwater bacteria by nanoflagellates in an organic-contaminated aquifer.

Time series incubations were conducted to provide estimates for the size selectivities and rates of protistan grazing that may be occurring in a sandy, contaminated aquifer. The experiments involved four size classes of fluorescently labeled groundwater bacteria (FLB) and 2- to 3-microns-long nanoflagellates, primarily Spumella guttula (Ehrenberg) Kent, that were isolated from contaminated aquifer sediments (Cape Cod, Mass.). The greatest uptake and clearance rates (0.77 bacteria.flagellate-1.h-1 and 1.4 nl.flagellate-1.h-1, respectively) were observed for 0.8- to 1.5-microns-long FLB (0.21-microns3 average cell volume), which represent the fastest growing bacteria within the pore fluids of the contaminated aquifer sediments. The 19:1 to 67:1 volume ratios of nanoflagellate predators to preferred bacterial prey were in the lower end of the range commonly reported for other aquatic habitats. The grazing data suggest that the aquifer nanoflagellates can consume as much as 12 to 74% of the unattached bacterial community in 1 day and are likely to have a substantive effect upon bacterial degradation of organic groundwater contaminants.

Bacteria↗

PubMed1997

Effect of flagellates on free-living bacterial abundance in an organically contaminated aquifer.

Little is known about the role of protists in the saturated subsurface. Porous media microcosms, containing bacteria and protists, were used to determine whether flagellates from an organically contaminated aquifer could substantively affect the number of free-living bacteria (FLB). When flagellates were present, the 3-40% maximum breakthrough of fluorescently labelled FLB injected into the microcosms was much lower than the 60-130% observed for killed controls. Grazing and clearance rates (3-27 FLB flag-1 h-1 and 12-23 nl flag-1 h-1, respectively) calculated from the data were in the range reported for flagellates in other aqueous environments. The data provide evidence that flagellate bacterivory is an important control on groundwater FLB populations.

Animals↗

PubMed1997

Protistan communities in aquifers: a review.

Eukaryotic microorganisms (protists) are a very important component of microbial communities inhabiting groundwater aquifers. This is not unexpected when one considers that many protists feed heterotrophically, by means of either phagotrophy (bacterivory) or osmotrophy. Protistan numbers are usually low (< 10(2) per g dw of aquifer material) in pristine, uncontaminated aquifers but may increase by several orders of magnitude in aquifers subject to organic pollution. Small flagellates (typically 2-3(5) microns in size in situ) are by far the dominant protists in aquifers, although amoebae and occasionally ciliates may also be present in much lower numbers. Although a wealth of new taxonomic information is waiting to be brought to light, interest in the identity of aquifer protists is not exclusively academic. If verified, the following hypotheses may prove to be important towards our understanding of the functioning of microbial communities in aquifers: (1) Differences in swimming behavior between species of flagellates lead to feeding heterogeneity and niche differentiation, implying that bacterivorous flagellates graze on different subsets of the bacterial community, and therefore play different roles in controlling bacterial densities. (2) Bacterivorous flagellates grazing on bacteria capable of degrading organic compounds have an indirect effect on the overall rates of biodegradation.

Animals↗

PubMed1997

Microorganisms as tracers in groundwater injection and recovery experiments: a review.

Modern day injection and recovery techniques designed to examine the transport behavior of microorganisms in groundwater have evolved from experiments conducted in the late 1800s, in which bacteria that form red or yellow pigments were used to trace flow paths through karst and fractured-rock aquifers. A number of subsequent groundwater hydrology studies employed bacteriophage that can be injected into aquifers at very high concentrations (e.g., 10(13) phage ml-1) and monitored through many log units of dilution to follow groundwater flow paths for great distances, particularly in karst terrain. Starting in the 1930s, microbial indicators of fecal contamination (particularly coliform bacteria and their coliphages) were employed as tracers to determine potential migration of pathogens in groundwater. Several injection and recovery experiments performed in the 1990s employed indigenous groundwater microorganisms (both cultured and uncultured) that are better able to survive under in situ conditions. Better methods for labeling native bacteria (e.g. by stable isotope labeling or inserting genetic markers, such as the ability to cause ice nucleation) are being developed that will not compromise the organisms' viability during the experimental time course.

Enterobacteriaceae↗

PubMed1996

Immunization against growth hormone releasing factor or chronic feed restriction initiated at 3.5 months of age reduces ovarian response to pulsatile administration of gonadotropin-releasing hormone at 6 months of age and delays onset of puberty in heifers.

A severe or moderate suppression of serum insulin-like growth factor I (IGF-I) was induced in heifers, beginning at 104 days of age, by active immunization against growth hormone-releasing factor (GRFi) or by chronic feed restriction (RES), respectively. We hypothesized that reduced serum IGF-I results in decreased serum estradiol-17 beta (E2), which in turn delays onset of puberty. The objectives of this experiment were to determine 1) whether GRFi and RES would alter follicular development and delay onset of puberty through similar mechanisms, and 2) whether GnRH would enhance follicular growth in control, GRFi, and RES heifers at 6 mo of age. Changes in IGF-I, somatotropin, LH, FSH, and E2 were evaluated. Serum IGF-I was greater in control than in RES heifers, and was greater in both these groups than in GRFi heifers by 169 days of age. Basal LH decreased in control and RES but not in GRFi heifers from 136 to 157 days of age. During the same period, a decrease in mean FSH was detected in control but not in GRFi and RES heifers. RES decreased mean serum E2 from 148 to 183 days of age. At 6 mo of age, pulsatile administration of GnRH (5 micrograms every 2 h for 42-46 h) increased serum LH and FSH similarly across treatments but had no effect on the number of follicles > or = 8 mm in GRFi and RES heifers relative to saline treatment. Serum E2 and IGF-I in follicular fluid from follicles > or = 8 mm were increased in all GnRH-treated heifers; however, concentrations of both hormones were lower in GRFi than in control or RES heifers. The main effect of treatments on serum IGF-I was reflected in follicles < or = 7 mm; follicular fluid IGF-I was greater in control than in RES heifers and was greater in both these groups than in GRFi heifers. Serum E2 was lower in RES than in control and GRFi heifers from 253 to 281 days of age. Because of an interaction, E2 was lower in GRFi-GnRH than in control-GnRH heifers but similar in GRFi-saline and control-saline heifers. By 393 days of age, 0% of RES and 32% of GRFi heifers had reached puberty compared to 71% of control heifers. These data support our hypothesis that decreased serum IGF-I results in decreased serum E2. GRFi appears to delay puberty in heifers because decreased serum IGF-I impairs the ovary's ability to synthesize preovulatory concentrations of E2, thereby delaying stimulation of an LH surge. In contrast, RES may delay puberty by delaying follicular development at two stages: a) decreased IGF-I in follicles < or = 7 mm may delay predominant follicular growth, and b) decreased LH may delay maturation of the preovulatory follicle.

Aging↗

PubMed1996

Ovarian expression of insulin-like growth factor-I (IGF-I), IGF binding proteins, and growth hormone (GH) receptor in heifers actively immunized against GH-releasing factors.

Active immunization against GRF at 6 months of age delays puberty in beef heifers. The objectives of the present study were to determine whether active immunization against GRF at an earlier age would affect normal onset of puberty and follicular growth and to determine whether these changes were related to alterations in ovarian insulin-like growth factor I (IGF-I) or IGF binding protein (IG-FBP) messenger RNA (mRNA) levels. Heifers were immunized against human serum albumin (HSAi; n = 15) or against GRF conjugated to HSA (GRFi; n = 18) at 3 months of age. A third group of heifers was not immunized (CON; n = 16). Immunization against GRF delayed puberty beyond 13 months of age in 75% of treated heifers. Unilateral ovariectomy at 191 days of age revealed that the delay in puberty was associated with a reduction in the number of large ( > or = 7 mm in diameter) follicles. Large follicles were present in only 22% of GRFi heifers compared to 77% of HSAi heifers. The number of small ( < or = 3 mm in diameter) and medium (4 to 6 mm in diameter) follicles was not affected by GRFi. The percentage of 1- to 3-mm follicles that were atretic was not different between HSAi (65%) and GRFi (62%) heifers. Unilateral ovariectomy had no effect on age at puberty. Immunization against GRF decreased (P < 0.01) concentrations of IGF-I in serum (23 +/- 2 ng/ml) compared to HSAi heifers (109 +/- 11 ng/ml). IGF-I levels in follicular fluid (FFL) of medium and small follicles were also decreased by GRFi from 82 +/- 3 ng/ml in HSAi heifers to 48 +/- 6 ng/ml (P < 0.01). Levels of IGFBP-3 (determined by ligand blot analysis) in serum and FFL of small follicles were decreased by GRFi (P < 0.01). In contrast, IGFBP-2 serum levels were increased from 422 +/- 32 ng/ml in HSAi heifers to 657 +/- 6 ng/ml in GRFi heifers (P < 0.05). Likewise, IGFBP-2 levels in FFL from small and medium follicles were increased from 785 +/- 44 ng/ml to 926 +/- 44 ng/ml (P < 0.05). Ligand blot analysis indicated that IGFBP levels were lower in FFL from large vs. small follicles. The band intensities of IGFBP-4 and -5 were drastically reduced ( > 80%) while the decreases in IGFBP-2 and -3 were less marked ( < 50%). The decreased levels of IGFBP-5 in FFL from large follicles was not associated with an increase in proteolytic fragments detectable by immunoblot analysis. While mRNA transcripts for IGF-I, GH receptor, and IGFBP-2, -3, -4, and -5 were readily detectable in ovarian tissue, GRFi had no effect on ovarian levels of mRNA for each of these proteins. This suggests that the decrease in follicular development associated with GRFi may be related to changes in circulating IGF-I and/or IGFBPs.

Animals↗

PubMed1996

Forage characteristics, steer performance, and water quality from bermudagrass pastures fertilized with two levels of nitrogen from swine lagoon effluent.

Four .8-ha pastures of bermudagrass (Cynodon dactylon [L.] Pers.) were fertilized with either 456 or 873 kg/ha of nitrogen (N) from swine lagoon effluent (two replicates per treatment) and grazed by steers over two summers. Within each pasture, steers received forage only, an energy source (corn), a mixture of corn and soybean meal, or a mixture of corn and blood meal via electronic Calan feeders. All supplements were offered at a level of 1.36 kg/d, and the soybean meal and blood meal supplements provided similar among quantities of protein. Weight gains were similar among supplemented steers, but supplemented steers gained faster (P < .05) than controls. Nitrogen fertilization level had no effect on steer gains, steer grazing days per hectare, or in vitro dry matter disappearance, NDF, and ADF of clipped forage samples. Plant protein and nitrate ion concentrations were greater (P < .06) in clipped forage samples receiving the higher N application rate. Nitrate ion concentrations were greater in available forage samples from the pastures with the high N application rate. Mean total N and nitrate N concentrations were similar in water samples obtained from monitoring wells for the two N treatments over the 2 yr and there were no year x N interactions. Chloride concentrations were greater (P < .05) and pH and specific conductance were less in water samples collected from the 873 kg than from the 456 kg/ha N treatment. Long-term studies are needed to examine the possible cumulative effects of applying various levels of swine waste to the same land area.

Animal Feed↗

PubMed1996

Application of nitrogen from swine lagoon effluent to bermudagrass pastures: seasonal changes in forage nitrogenous constituents and effects of energy and escape protein supplementation on beef cattle performance.

A 2-yr study was conducted to evaluate 1) the effects of nitrogen level from swine lagoon effluent on forage composition and animal performance and 2) the effects of supplemental escape protein (EP) on performance by steers grazing pastures fertilized with swine lagoon effluent. Bermudagrass (Cynodon dactylon) pastures were fertilized via sprinkler irrigation with either 448 or 896 kg/ha of N from swine lagoon effluent (two pasture replications/treatment). Within each pasture, four supplement treatments were evaluated using electronic Calan gates (8 steers.pasture-1.yr-1). The treatments were 1) negative control (pasture only); 2) energy control, which supplied 79.9 g of EP.hd-1.d-1; 3) 159 g of EP.hd-1.d-1, and 4) 239 g of EP.hd-1.d-1. Gains were increased (P < .05) an average of .15 kg/d by supplementation, with no differences in gain among supplements. Forage samples representative of that grazed by steers (CONSUM) and representative of all available forage (AVAIL) were obtained at 14-d intervals. Total CP content of CONSUM and AVAIL samples were slightly higher (P < .20 and P < .15, respectively) from pastures fertilized with 896 compared with 448 kg/ha of N (20.8 vs 20.0% for CONSUM and 15.2 vs 14.2% for AVAIL). Concentrations of nonprotein N and soluble true protein (% of CP) in both AVAIL and CONSUM samples were higher (P < .06) from pastures fertilized with the higher N level. Total N uptake by the plant, based on CP content and animal grazing days/ha, was essentially the same for both N treatments.

Ammonia↗

PubMed1995

Transport behavior of groundwater protozoa and protozoan-sized microspheres in sandy aquifer sediments.

Transport behaviors of unidentified flagellated protozoa (flagellates) and flagellate-sized carboxylated microspheres in sandy, organically contaminated aquifer sediments were investigated in a small-scale (1 to 4-m travel distance) natural-gradient tracer test on Cape Cod and in flow-through columns packed with sieved (0.5-to 1.0-mm grain size) aquifer sediments. The minute (average in situ cell size, 2 to 3 (mu)m) flagellates, which are relatively abundant in the Cape Cod aquifer, were isolated from core samples, grown in a grass extract medium, labeled with hydroethidine (a vital eukaryotic stain), and coinjected into aquifer sediments along with bromide, a conservative tracer. The 2-(mu)m flagellates appeared to be near the optimal size for transport, judging from flowthrough column experiments involving a polydispersed (0.7 to 6.2 (mu)m in diameter) suspension of carboxylated microspheres. However, immobilization within the aquifer sediments accounted for a log unit reduction over the first meter of travel compared with a log unit reduction over the first 10 m of travel for indigenous, free-living groundwater bacteria in earlier tests. High rates of flagellate immobilization in the presence of aquifer sediments also was observed in the laboratory. However, immobilization rates for the laboratory-grown flagellates (initially 4 to 5 (mu)m) injected into the aquifer were not constant and decreased noticeably with increasing time and distance of travel. The decrease in propensity for grain surfaces was accompanied by a decrease in cell size, as the flagellates presumably readapted to aquifer conditions. Retardation and apparent dispersion were generally at least twofold greater than those observed earlier for indigenous groundwater bacteria but were much closer to those observed for highly surface active carboxylated latex microspheres. Field and laboratory results suggest that 2-(mu)m carboxylated microspheres may be useful as analogs in investigating several abiotic aspects of flagellate transport behavior in groundwater.

Journal Article↗

PubMed1995

Recombinant bovine somatotropin increases milk yield and calf gain in diverse breeds of beef cattle: associated changes in hormones and indices of metabolism.

In Exp. 1, Angus (A, n = 30), Charolais (C, n = 37), and Simmental (S, n = 30) multiparous cows received (s.c.) recombinantly derived bovine somatotropin (bST; sometribove, 500 mg) or vehicle (VEH) at 2-wk intervals from 124 to 228 d postpartum (DPP). Calves were weaned at 228 DPP. Bovine somatotropin increased (P < .01) milk yield and percentage of milk fat similarly in A, C, and S cows. Calf weaning weight was greater (P < .05) in cows treated with bST than in those given VEH. Administration of bST decreased deposition of fat and increased concentrations of IGF-I, insulin, glucose, and nonesterified fatty acids. In Exp. 2, we compared effects of bST initiated before or after the breeding season. Charolais (n = 33) and S (n = 40) cows were administered (at 2-wk intervals) VEH or bST beginning at 28 DPP (B-bST) or bST beginning at 105 DPP (A-bST). Calves were weaned at 243 DPP. Administration of bST before or after the breeding season increased milk yield on DPP 136 and 194; however, yields were greater in A-bST than in B-bST cows. Milk yields were similar in all cows at 236 DPP, corresponding to decreased forage availability. Calf body weight was greater (P < .05) in A-bST than VEH; B-bST calves were similar to VEH. Fat depth was greater in VEH than in bST-treated cows in C but not in S cows. Serum IGF-I was greater in A- and B-bST than in VEH cows. Mean days from calving to serum progesterone > 1 ng/mL and pregnancy rates were similar in VEH, A-, and B-bST cows. Administration of bST increased cow milk yield and subsequent calf weaning weight when initiated after 100 d postpartum. As anticipated, bST increased IGF-I, insulin, glucose, and nonesterified fatty acids. Administration of bST before and during the breeding season did not affect reproductive performance.

Animals↗

PubMed1995

Subclinical mastitis and milk production in primiparous Simmental cows.

The prevalence of subclinical mastitis in beef cows was investigated and its relationship with milk production and 205-d adjusted calf weaning weights (ADJWW) determined. Primiparous Simmental cows (n = 25) were milked six times at approximately 30-d intervals. Before each milking, milk samples were aseptically collected from each quarter for bacteriological analyses. After recording milk weights, samples were obtained for determination of somatic cell counts (SCC), butterfat (BF), and protein (PRO). Somatic cell counts were transformed to Dairy Herd Improvement Association linear scores for statistical analyses. Cows were retrospectively assigned to one of two groups based on their SCC linear score being either less than (LOSCC) or more than (HISCC) 4.5, which corresponded to a SCC of 292 x 10(3) cells/mL. Milk samples from 32% (8/25) of the cows and 18% (18/100) of the quarters were culture-positive for bacteria (Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus species, Actinomyces pyogenes, and[or] coagulase-negative Staphylococcus) at one or more times. Milk production was higher in LOSCC than in HISCC cows (6.3 +/- .2 vs 5.4 +/- .3 kg/24 h; P = .004). Mean SCC linear score tended to be negatively correlated with mean milk production over the entire study (r = -.36; P = .08). Adjusted weaning weights were similar between calves suckling LOSCC and HISCC cows (243 +/- 5 vs 236 +/- 10 kg; P = .57). In summary, milk SCC concentrations in primiparous Simmental cows were highly variable. Higher SCC concentrations were associated with lower milk production in cows.

Animals↗

PubMed1995

Endocrine and ovarian responses to exogenous estradiol-17 beta in 6-month-old heifers previously immunized against growth hormone-releasing factor.

We hypothesized that estradiol-17 beta (E2) was capable of stimulating an LH surge in 6-mo-old heifers immunized against growth hormone-releasing factor (GRFi). To test this hypothesis Angus x Simmental heifers were immunized against GRF (n = 11) or human serum albumin (HSAi) (n = 6) at 113 d of age. Heifers were injected i.m. with 500 micrograms of E2 at 172 d of age. To characterize the LH response, samples were collected at frequent intervals for 1 h before and 32 h after E2. To assess ovarian responses, real-time ultrasonography was performed from d 9 to 20, and serum progesterone was evaluated from d 6 to 25 after E2, then weekly for 13 wk. Exogenous E2 stimulated (P < .001) LH surges, preceded by negative E2 feedback that decreased serum LH, in all GRFi and HSAi heifers. During the negative feedback period, serum LH was greater (P < .001), and the change in LH from before to after E2 was lower (P < .05), in GRFi than in HSAi heifers. Puberty occurred in 7/17 heifers within 66 d after receiving E2. We conclude that GRFi does not impair the release of an E2-induced LH surge, but it does decrease hypothalamo-hypophyseal sensitivity to the inhibitory effect of E2.

Animals↗

PubMed1994

Effect of somatotropin and/or equine chorionic gonadotropin on serum and follicular insulin-like growth factor I and insulin-like growth factor binding proteins in cattle.

We investigated the effect of administration of somatotropin (ST) and/or eCG on insulin-like growth factor I (IGF-I) and IGF-binding proteins (IGFBP) in serum and follicular fluid (FFL) of cattle actively immunized against growth hormone-releasing factor (GRF). Cyclic beef cattle, previously immunized against GRF-(1-29)-Gly-Gly-Cys-NH2 conjugated to human serum albumin (synthesized and provided by Hoffmann-LaRoche, Inc., Nutley, NJ; GRFi, n = 31) or to human serum albumin alone (HSAi, n = 26), received (i.m.): 1) 25 mg recombinantly derived methionyl somatotropin (rbST, n = 14; sometribove provided by Monsanto Co., St. Louis, MO); 2) 1100 IU eCG (n = 10); 3) rbST and eCG (rbST-eCG, n = 15); or 4) vehicle (VEH, n = 17) at 0 and 24 h after receiving prostaglandin F2 alpha (PGF2 alpha). Serum samples were collected at 0 and 40 h after PGF2 alpha, and the ovary bearing the largest follicle (DOM) was removed 44.0 +/- 0.5 h after PGF2 alpha; FFL was harvested from DOM and the subordinate follicle (SUB). Before treatment (0 h), GRFi cows had lower serum ST (0.6 +/- 0.2 vs. 2.2 +/- 0.2 ng/ml; p < 0.01) and IGF-I (26 +/- 4 vs. 72 +/- 4 ng/ml; p < 0.01), but greater IGFBP-2 (594 +/- 48 vs. 384 +/- 52 ng/ml; p < 0.01) than HSAi cows. Serum and FFL concentrations of IGF-I or IGFBP-2 were not different between rbST- and rbST-eCG-treated cows or between VEH- and eCG-treated cows at Hour 40 after the initial treatment injection; therefore, data were combined and designated as rbST and VEH, respectively. Serum IGF-I was increased to a greater extent (percentage increase above 0 h) by rbST treatment in GRFi (362 +/- 24) than in HSAi (176 +/- 16) cows (immunization by treatment, p < 0.01). Across GRFi and HSAi, rbST lowered serum IGFBP-2 (342 +/- 31 vs. 541 +/- 27 ng/ml, rbST vs. VEH; p < 0.01). Diameters of DOM or SUB were not affected by immunization or treatment. Concentrations of IGF-I and IGFBP-3 (determined by ligand blot analysis) in FFL from both DOM and SUB were lower (p < 0.05) in GRFi than in HSAi cows. In contrast, IGFBP-2 in FFL was elevated in SUB, but not DOM, in GRFi compared to HSAi cows.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1994

Effect of daily replacement therapy with recombinant bovine somatotropin on somatotropin, insulin-like growth factor I, and onset of puberty in beef heifers immunized against growth hormone-releasing factor.

Two experiments examined whether replacement therapy with recombinantly derived bovine somatotropin (rbST) would induce puberty in heifers that had been actively immunized at 6 mo of age against growth hormone-releasing factor (GRF). Heifers received daily i.m. injections of 25 mg of rbST (Exp. 1, n = 6; Exp. 2, n = 4) or vehicle (VEH; Exp. 1, n = 6; Exp. 2, n = 4) for 56 d. Serum concentrations of somatotropin (ST, nanograms/milliter) were low in all heifers before first injection in Exp. 1 (1.56 +/- .04) and 2 (.95 +/- .03). During treatment, serum ST was greater (P < .01) in rbST than in VEH heifers (75.4 +/- 4.8 vs 2.8 +/- .1 ng/mL, respectively) in both experiments and remained increased through d 57 (32.2 +/- 6.4 vs .90 +/- .01 ng/mL). IN Exp. 1 and 2, concentrations of serum IGF-I were similar in rbST and VEH heifers before treatment, increased (P < .01) 12 h after first rbST, and remained increased (P < .01) through d 57 in rbST heifers. Concentrations of serum insulin (INS) and plasma glucose (GLU) were similar (P > .10) in rbST and VEH heifers before first injection (Exp. 1 and 2). Serum INS (micro-units/milliliter) was greater (P < .01) in rbST (61.7 +/- 3.7 and 36.0 +/- 2.4) than in VEH (12.4 +/- 1.6 and 8.1 +/- 1.0) heifers on d 1 or 2 only, in Exp. 1 and 2, respectively. In Exp. 1, GLU was increased (P < .05) by rbST on d 2 through 57, but only on d 1 in Exp. 2. Proportion of heifers pubertal by d 21 tended to be greater (P < .07) in rbST (3 of 6) than in VEH (0 of 5) heifers in Exp. 1, but not in Exp. 2 (1 of 4 vs 1 of 4, respectively). All heifers in Exp. 1 and 50% of the heifers in Exp. 2 attained puberty by d 56. Daily rbST increased ST, IGF-I, INS, and GLU but did not hasten onset of puberty in heifers immunized against GRF.

Animals↗