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Biomedical subjects

M E White

Publications and source records attributed to M E White.

At least 19 recordsLinked to original sources
PubMed2003

Prevalence of Giardia spp. and Cryptosporidium spp. on dairy farms in southeastern New York state.

A prevalence study was designed to determine the presence of Cryptosporidium spp. and Giardia spp. in the soil of 37 dairy farms in southeastern New York state. A sampling design was developed and used to collect soil samples from these farms. Areas on the farms which were considered to be potential sources of contamination to the environment were evaluated quantitatively using a multidimensional scale. This scale included factors which could have the potential to contribute to the risk of contamination of the environment with Giardia or Cryptosporidium. In addition, the runoff pathway from these areas was identified and sampling points along that pathway were determined. Using a sampling grid, sampling sites were determined and soil samples collected and analyzed individually for the following: presence of Giardia and Cryptosporidium, pH, gravimetric moisture content, and volumetric moisture content. Out of 782 soil samples, 17% were positive for Cryptosporidium and 4% were positive for Giardia. The pH of the soil ranged from 3.7 to 9.8 with a mean of 7.0. There was a significant association between the pH and the likelihood of detecting Cryptosporidium spp. As the pH increased, the likelihood of detecting an oocyst decreased. Gravimetric moisture content had a mean of 40% and a range from 7 to 86%. There was a significant association between the gravimetric moisture content and the likelihood of detecting Giardia in soil samples.

Animals↗
PubMed2003

Effect of differentiation on levels of insulin-like growth factor binding protein mRNAs in cultured porcine embryonic myogenic cells.

Insulin-like growth factor binding proteins (IGFBPs) have been shown to affect proliferation of several cell types via insulin-like growth factor (IGF)-dependent and IGF-independent mechanisms. The goal of this study was to determine if levels of IGFBP-2, -3, -4 and -5 mRNA changed during differentiation of cultured porcine embryonic myogenic cells. Total RNA was isolated from muscle cultures at various stages of differentiation and Northern blots of this RNA were probed with 32P-labeled cDNA probes specific for individual IGFBPs. Fusion, myogenin mRNA, and creatine phosphokinase activity were used as markers of differentiation. The level of IGFBP-3 mRNA in differentiating cultures (120 h in culture) was only one-third of the level in myogenin negative, nonfused cultures (72 h in culture) (P < 0.05, n = 4). In contrast, the level of IGFBP-3 mRNA in extensively fused cultures (144 h in culture) was increased by three-fold as compared to the level in myogenin negative, nonfused cultures (P < 0.05, n = 4) and approximately seven-fold as compared to the 120-h cultures (P < 0.05, n = 4). No significant change in the level of IGFBP-5 mRNA was observed during differentiation of myogenic cultures. IGFBP-2 mRNA levels were not significantly different at 72, 96 and 120 h, but at 144 h IGFBP-2 mRNA level was increased three-fold as compared to nonfused cultures (72 h) (P < 0.05, n = 4). IGFBP-4 mRNA was not detectable on Northern blots of total RNA from porcine myogenic cultures at any stage of differentiation. Changes in IGFBP-3 and IGFBP-2 mRNA levels are associated with differentiation of embryonic porcine myogenic cells in culture and this may indicate that these IGFBPs play a role in differentiation of these cells.

Animals↗
PubMed2003

Effect of recombinant porcine IGF-binding protein-3 on proliferation of embryonic porcine myogenic cell cultures in the presence and absence of IGF-I.

IGF-binding protein (IGFBP)-3 is produced by cultured porcine embryonic myogenic cell (PEMC) cultures and is secreted into the medium. Levels of secreted IGFBP-3 and IGFBP-3 mRNA are significantly reduced during differentiation and increase after differentiation is complete, suggesting that IGFBP-3 may play some role in myogenesis and/or in changes in myogenic cell proliferation that accompany differentiation. IGFBP-3 reportedly may either suppress or stimulate proliferation of cultured cells depending on cell type. Additionally, IGFBP-3 has been shown to affect proliferation via both IGF-dependent and IGF-independent mechanisms in some cell types but not all. Currently, the effect, if any, of IGFBP-3 on myogenic cell proliferation is not known. Consequently, the goal of this study was to assess the IGF-I-dependent and IGF-I-independent actions of recombinant porcine IGFBP-3 on proliferation of cultured porcine myogenic cells. To facilitate these investigations, we have expressed porcine IGFBP-3 in the baculovirus system, purified and characterized the expressed recombinant porcine IGFBP-3 (rpIGFBP-3), and produced and characterized an anti-porcine IGFBP-3 antibody that neutralizes the biological activity of porcine IGFBP-3. rpIGFBP-3 suppressed IGF-I-stimulated proliferation of PEMCs in a concentration-dependent manner with equimolar concentrations of IGF-I and rpIGFBP-3, resulting in complete suppression of IGF-I-stimulated proliferation. rpIGFBP-3 also suppressed Long-R3-IGF-I-stimulated proliferation of PEMC, indicating that rpIGFBP-3 possesses IGF-independent activity in this cell system. These data have established that IGFBP-3 has the potential to affect proliferation of PEMCs during critical periods of muscle development that may impact ultimate muscle mass achievable postnatally.

Animals↗
PubMed2003

Growth factor messenger RNA levels in muscle and liver of steroid-implanted and nonimplanted steers.

Ribonuclease protection assays were used to measure steady-state semimembranosus muscle and/or hepatic levels of IGF-I, IGFBP-3, IGFBP-5, hepatocyte growth factor (HGF), and myostatin messenger RNA (mRNA) in steers implanted from 32 to 38 d with Revalor-S, a combined trenbolone acetate and estradiol implant. Insulin-like growth factor-ImRNA levels were 69% higher (P < 0.01, n = 7) in the livers of implanted steers than in the livers of nonimplanted steers. Similarly, IGF-I mRNA levels were 50% higher (P < 0.05, n = 7) in the semimembranosus muscles of implanted steers than in the same muscles from nonimplanted steers. Hepatic IGFBP-3 mRNA levels were 24% higher (P < 0.07, n = 7) in implanted steers than in nonimplanted steers. Hepatic HGF and IGFBP-5 mRNA levels did not differ between implanted and nonimplanted steers. Similarly, muscle IGFBP-3, IGFBP-5, HGF, and myostatin mRNA levels were not affected by treatment. Previous data from these same steers have shown that circulating IGF-I and IGFBP-3 concentrations were 30 to 40% higher (P < 0.01, n = 7) in implanted steers than in nonimplanted, control steers. Additionally, the number of actively proliferating satellite cells that could be isolated from the semimembranosus muscle was 45% higher (P < 0.01, n = 7) for implanted steers than for nonimplanted steers. Viewed together, these data suggest that increased muscle IGF-I levels stimulate increased satellite cell proliferation, resulting in the increased muscle growth observed in Revalor-S implanted steers.

Anabolic Agents↗
PubMed2003

Effects of antimicrobials and weaning on porcine serum insulin-like growth factor binding protein levels.

The effects of subtherapeutic antimicrobial supplementation and weaning on serum levels of IGF-I and insulin-like growth factor binding proteins (IGFBP)-2, -3 and -4 were determined in crossbred weanling pigs. At weaning, pigs were allotted to a diet containing 21.8% crude protein and 1.15% lysine with or without Aureozol (110 mg/kg of Aureomycin chlortetracycline, 110 mg/kg of sulfathiazole, and 55 mg/kg of penicillin) for 4 wk. Insulin-like growth factor-binding proteins and IGF-I analyses were performed on blood samples that were drawn weekly. Weaning decreased serum IGFBP-3 levels in both control and Aureozol-treated groups on d 6 and d 14 (P < 0.05) relative to preweaning levels. The IGFBP-3 values returned to preweaning levels by d 21. Although the circulating levels of both the 43-kDa and the 39-kDa glycosylation variants of IGFBP-3 were affected by weaning, the level of the 39-kDa IGFBP-3 was affected relatively more than that of the 43-kDa IGFBP-3 (P < 0.05). Compared with circulating IGFBP-3 levels in control pigs, Aureozol-treated pigs had higher circulating IGFBP-3 levels on d 21 (43%, P < 0.05) and d 27 (46%, P < 0.05). In direct contrast to the effect of weaning on serum IGFBP-3 level, serum IGFBP-2 levels increased on d 6 and d 14 after weaning (P < 0.05) and decreased to preweaning levels by d 21. The IGFBP-2 levels continued to decline and were less than preweaning levels by d 27 (P < 0.05). Aureozol treatment had no effect on serum IGFBP-2 levels at any time. Serum levels of nonglycosylated IGFBP-4 were not affected by either weaning or Aureozol supplementation. Weaning decreased circulating IGF-I concentration on d 6 in both control and Aureozol-treated pigs (76 and 73%, respectively, P < 0.05) and on d 14 (62%, P < 0.05) and d 21 (32%, P < 0.05) in control pigs. Aureozol-supplemented pigs had higher serum IGF-I concentrations than control pigs on d 14 (82%, P < 0.05), d 21 (55%, P < 0.05), and d 27 (36%, P < 0.05). The Aureozol-fed pigs had a 14.2% increase in BW gain (P < 0.05) and a 59.6% increase in ADG (P < 0.05) compared with pigs fed the control diet. Both Aureozol-supplementation and weaning cause changes in serum IGFBP levels and IGF-I concentrations that might be involved in regulating rate and efficiency of growth.

Animal Feed↗
PubMed2003

Factors associated with the likelihood of Giardia spp. and Cryptosporidium spp. in soil from dairy farms.

A study was conducted to identify factors associated with the likelihood of detecting Giardia spp. and Cryptosporidium spp. in the soil of dairy farms in a watershed area. A total of 37 farms were visited, and 782 soil samples were collected from targeted areas on these farms. The samples were analyzed for the presence of Cryptosporidium spp. oocysts, Giardia spp. cysts, percent moisture content, and pH. Logistic regression analysis was used to identify risk factors associated with the likelihood of the presence of these organisms. The use of the land at the sampling site was associated with the likelihood of environmental contamination with Cryptosporidium spp. Barn cleaner equipment area and agricultural fields were associated with increased likelihood of environmental contamination with Cryptosporidium spp. The risk of environmental contamination decreased with the pH of the soil and with the score of the potential likelihood of Cryptosporidium spp. The size of the sampling site, as determined by the sampling design, in square feet, was associated nonlinearly with the risk of detecting Cryptosporidium spp. The likelihood of the Giardia cyst in the soil increased with the prevalence of Giardia spp. in animals (i.e., 18 to 39%). As the size of the farm increased, there was decreased risk of Giardia spp. in the soil, and sampling sites which were covered with brush or bare soil showed a decrease in likelihood of detecting Giardia spp. when compared to land which had managed grass. The number of cattle on the farm less than 6 mo of age was negatively associated with the risk of detecting Giardia spp. in the soil, and the percent moisture content was positively associated with the risk of detecting Giardia spp. Our study showed that these two protozoan exist in dairy farm soil at different rates, and this risk could be modified by manipulating the pH of the soil.

Agriculture↗
PubMed2001

Partnerships in international applied epidemiology training and service, 1975-2001.

In 1951 the Centers for Disease Control and Prevention created the Epidemic Intelligence Service to provide training and epidemiologic service on the model of a clinical residency program. By January 2001, an additional 28 applied epidemiology and training programs (AETPs) had been implemented around the globe (with over 945 graduates and 420 persons currently in training). Field Epidemiology Training Programs and Public Health Schools Without Walls are the most common models. Applied epidemiologists, or field epidemiologists, use science as the basis for intervention programs designed to improve public health. AETPs train people by providing them with health competencies through providing service to public health intervention programs and strengthening health systems. AETPs are relatively expensive to create and maintain, but they are highly sustainable and can produce immediate benefits. Of the 19 programs that began before 1997, 18 (95%) continue to produce graduates. The Training Programs in Epidemiology for Public Health Interventions Network was organized in 1997 to provide support, peer review, and quality assurance for AETPs. In 2001, new programs are planned or in development in India, Argentina, China, and Russia.

Centers for Disease Control and Prevention, U.S.↗
PubMed2001

Effects of growth factors on insulin-like growth factor binding protein (IGFBP) secretion by primary porcine satellite cell cultures.

Insulin-like growth factor-binding proteins (IGFBP) regulate the biological functions of insulin-like growth factors (IGF) and may affect cell growth through IGF-independent actions. Growth factors and hormones have been shown to alter IGFBP production by target cells suggesting that the effects of these factors may be partially mediated by the local production of IGFBP. Growth factors, including IGF-I, transforming growth factor-beta1 (TGF-beta1), and basic fibroblast growth factor (bFGF) have potent effects on satellite cell proliferation and differentiation, and some of these factors have been shown to alter IGFBP production in various cell types. Consequently, some of their actions on muscle satellite cells may be mediated by the local production of IGFBP. In this study, we measured the effects of IGF-I, bFGF, and TGF-beta1 on IGFBP production by primary porcine satellite cell (PSC) cultures after first determining physiologically active concentrations of these growth factors to use according to [3H]thymidine incorporation dose responses. There is little information on the effects of these growth factors on IGFBP production in primary porcine myogenic cells due to the confounding affects of contaminating nonmuscle fibroblasts. Comparative studies show that primary porcine satellite cells produce IGFBP-3 and -5 whereas porcine muscle-derived nonfusing cells (FIB) produce IGFBP-2 and -4 but not IGFBP-3 or -5. Because of this, our investigations have focused on growth factor-induced production of IGFBP-3 and -5 in primary porcine satellite cells cultures. Both IGF-I and bFGF exhibited dose-dependent increases in [3H]thymidine incorporation with increasing concentration from 1 to 50 ng/mL (P < 0.05), whereas TGF-beta1 caused a dose-dependent decrease from 0.01 to 0.5 ng/mL (P < 0.05). When 20 ng/ mL of IGF-I was added to the media, IGFBP-3 was increased approximately 65% (P < 0.05) and IGFBP-5 was increased approximately twofold (P < 0.05). The addition of 0.5 ng/mL TGF-beta1 caused more than a two-fold increase in IGFBP-3 (P < 0.05) and approximately an 80% increase in IGFBP-5 (P < 0.05), whereas 50 ng/ mL of bFGF caused approximately 40% (P < 0.05) and 70% (P < 0.05) increases in IGFBP-3 and -5, respectively. Neither IGFBP-3 nor -5 was detectable in the conditioned media from fibroblasts whether or not IGF-I, TGF- beta1 or bFGF were present. These data suggest that the effects of IGF-I, TGF- beta1 and bFGF on porcine satellite cells may in part be through the autocrine/ paracrine production of IGFBP-3 and -5 by porcine satellite cells.

Animals↗
PubMed2000

Gene conversions may obscure actin gene family relationships.

Phylogenetic hypotheses of muscle actin evolution are significantly different when a sea urchin is used as a representative echinoderm than when a sea star is used. While sea urchin muscle actins support an echinoderm-chordate sister relationship, sea star sequences suggest that echinoderm muscle actins are convergent with chordate muscle actins. Our results suggest that gene conversion in the sea star muscle actin may be responsible for these discordant results.

Actins↗
PubMed2000

Effects of dietary lysine intake during lactation on blood metabolites, hormones, and reproductive performance in primiparous sows.

Effects of three dietary lysine (protein) concentrations during lactation on metabolic state, protein metabolism, reproductive hormones, and performance were investigated in 36 primiparous sows. Sows were assigned randomly to one of three diets containing .4% (low lysine, LL), 1.0% (medium lysine, ML), or 1.6% (high lysine, HL) total lysine from intact protein sources. All diets contained 2.1 Mcal NE/kg and exceeded the recommended requirements for all other nutrients. Actual lysine intakes over an 18-d lactation were 16, 36, and 56 g/d for sows fed LL, ML, and HL, respectively. Fractional breakdown rate of muscle was determined on d 4 and 15 of lactation by using a three-compartment kinetic model of 3-methylhistidine metabolism. Increasing lysine intake during lactation did not affect fractional breakdown rate of muscle on d 4 of lactation but decreased it on d 15 (P < .05). Sows fed LL had a reduced number of LH pulses on d 12 and 18 (P < .05) and reduced serum estradiol (E2) concentration on d 18 of lactation compared with sows fed ML and HL treatments. However, LH pulses and E2 concentrations were similar between ML and HL treatments (P > .35). Increasing lysine intake increased serum urea nitrogen (SUN) and postprandial insulin concentrations (P < .05) during lactation but had no effect on plasma glucose concentrations (P > .20). Sows fed HL had greater serum IGF-I on d 6 and 18 than sows fed ML (P < .05). Number of LH peaks was correlated with serum insulin concentration 25 min after feeding on d 6 and 18 (r = .31 to .41; P < .1) and pre- (r = .33 to .46) and postprandial (r = .30 to .58) SUN concentrations (P < .05) during different stages of lactation. Results indicate that, compared with medium lysine intake, low lysine intake increased muscle protein degradation and decreased concentrations of insulin, SUN, and estradiol and LH pulsatility. In contrast, high lysine (protein) intake increased SUN, insulin, and IGF-I, but did not increase secretion of estradiol and LH compared with medium lysine intake. Furthermore, nutritional impacts on reproduction may be mediated in part through associated effects on circulating insulin concentration.

Animals↗
PubMed2000

Insulin regulation of leptin expression in streptozotocin diabetic pigs.

The relationship between leptin mRNA and insulin status was explored using streptozotocin diabetic pigs. Twelve male Yorkshire x Landrace crossbred swine (approximately 40 kg BW) were divided into three groups. Two groups were rendered diabetic with the use of streptozotocin (75 mg/kg BW). Diabetes was confirmed 24 h after streptozotocin treatment by the presence of hyperglycemia. One group of diabetic animals received daily injections of insulin (.5 U/(kg x d)(-1)) for 7 d, whereas the other group of diabetic animals received saline injections. The nondiabetic group also received saline injections (controls). Tissue and blood were collected after 7 d of treatment. Leptin mRNA concentrations in dorsal s.c. adipose tissue were measured by Northern analysis and standardized against 28S rRNA expression. Diabetes reduced leptin mRNA concentration by 67% in s.c. adipose tissue (P < .05). Serum insulin concentrations in the diabetic animals were reduced by 69% (P < .05). Insulin treatment of diabetic animals resulted in an increase in leptin mRNA concentration to levels in controls. Primary cell culture of porcine adipose tissue was used to assess whether these actions were the direct or indirect action of insulin. Acute exposure (1 to 24 h) of primary cultures of porcine adipocytes to insulin did not result in a change in leptin expression. However, chronic (7-d) exposure to insulin elevated leptin mRNA levels by 73%. These data suggest that insulin mediates changes in porcine leptin mRNA levels in vivo or in vitro, most likely by an indirect action.

Animals↗
PubMed1999

Use of a water hardness test kit to measure serum calcium concentration in cattle.

OBJECTIVE: To determine whether a commercially available water hardness test kit could be used to measure total serum calcium concentration and diagnose hypocalcemia in dairy cows. DESIGN: Prospective study. ANIMALS: 30 dairy cows from 19 commercial herds. PROCEDURE: Serum calcium concentration was determined using a water hardness test kit and a standard, laboratory-based method. Simple linear regression was used to determine whether there was a linear relationship between results of the 2 methods, and Spearman's rank correlation was used to calculate correlation between measurements. Sensitivity, specificity, and predictive values of using test kit-derived values for diagnosis of hypocalcemia (laboratory value < 8 mg/dl) were calculated. RESULTS: There was a high correlation and significant linear relationship between results of the 2 methods. Sensitivity, specificity, predictive value of a positive test result, and predictive value of a negative test result were 100, 73, 86, and 100%, respectively. Accuracy was improved by using a test kit-derived calcium concentration of 7 mg/dl as the cut-off for determining hypocalcemia. CLINICAL IMPLICATIONS: Results indicate that a commercially available water hardness test kit can be used as a rapid, inexpensive method of estimating serum calcium concentrations and diagnosing hypocalcemia in dairy cattle. However, the test is not practical for cow-side use, because blood samples must be centrifuged to obtain serum for use in the test kit.

Animals↗
PubMed1999

Effect of insulin-like growth factor (IGF)-I and Des (1-3) IGF-I on the level of IGF binding protein-3 and IGF binding protein-3 mRNA in cultured porcine embryonic muscle cells.

Insulin-like growth factor binding protein (IGFBP)-3 effects proliferation and differentiation of numerous cell types by binding to insulin-like growth factors (IGF) and attenuating their activity or by directly affecting cells in an IGF-independent manner. Consequently, IGFBPs produced by specific cells may affect their differentiation and proliferation. In this study we show that embryonic porcine myogenic cells, unlike murine muscle cell lines, produce significant quantities of a binding protein immunologically identified as IGFBP-3. Nonfusing cells subcultured from highly fused porcine myogenic cell cultures do not produce detectable IGFBP-3 protein or mRNA, thus suggesting the IGFBP-3 is produced by muscle cells in the porcine myogenic cell cultures. Treatment of porcine myogenic cultures with 20 ng of IGF-I or 20 ng of Des (1-3) IGF-I/ml serum-free media for 24 h results in a threefold reduction in the level of IGFBP-3 in conditioned media. This reduction is not affected by cell density over a sixfold range. Additionally, treatment for 24 h with 20 ng of IGF-I/ml media results in a sevenfold decrease in the steady-state level of IGFBP-3 mRNA. This IGF-I-induced decrease in IGFBP-3 mRNA level appears to be relatively unique to myogenic cells. IGF-I treatment also causes a fourfold increase in the steady-state level of myogenin mRNA. This increase in myogenin mRNA suggests that, as expected, IGF-I treatment accelerates differentiation of myogenic cells. The simultaneous decrease in IGFBP-3 mRNA and protein that accompanies IGF-I-induced myogenin expression suggests that differentiation of myogenic cells may be preceded or accompanied by decreased production of IGFBP-3.

Animals↗
PubMed1999

Decreased steady-state insulin-like growth factor binding protein-3 (IGFBP-3) mRNA level is associated with differentiation of cultured porcine myogenic cells.

Insulin-like growth factor binding proteins (IGFBPs) affect the biological activity of IGF-I in several cell types, including cultured muscle cells. Additionally, at least one of the IGFBPs, IGFBP-3, has been shown to have IGF-independent effects on cell proliferation. Numerous studies have shown that immortalized muscle cell lines produce various IGFBPs, but to date no muscle cell line has been reported to produce IGFBP-3 protein or mRNA. Unlike muscle cell lines, primary cultures of porcine embryonic myogenic cells express IGFBP-3 mRNA and secrete a protein that is immunologically identifiable as IGFBP-3. Additionally, steady-state IGFBP-3 levels change significantly during differentiation. Here we report that differentiation of porcine myogenic cells in an IGFBP-3-free medium is accompanied by reduced steady-state IGFBP-3 mRNA levels. Steady-state levels of IGFBP-3 mRNA decreased approximately sevenfold (P < .05) during differentiation and then increased to predifferentiation levels once differentiation was complete. Addition of TGF-beta1 (0.5 ng/ml) to porcine myogenic cultures suppressed fusion and resulted in a sevenfold increase in steady-state IGFBP-3 mRNA and a 1.8-fold increase in IGFBP-3 protein levels as compared to untreated control cultures (P < .05). Results suggest that alterations in IGFBP-3 mRNA and protein may play a role in differentiation of porcine embryonic muscle cells.

Animals↗
PubMed1999

Effect of feed intake on antimicrobially induced increases in porcine serum insulin-like growth factor I.

This study was conducted to determine whether an antimicrobially induced (ASP-250) increase in serum IGF-I was the result of differences in feed intake. Serum IGF-I concentrations were measured in crossbred pigs that were fed a control diet or a diet supplemented with ASP-250 either for ad libitum consumption or limited to 85% of the control pigs' consumption. The pigs that consumed either diet ad libitum, control or ASP-250, consumed similar quantities of feed. The ASP-250 ad libitum-intake pigs had serum IGF-I concentrations that were greater (P<.01) than those of their ad libitum-intake control littermates. Similarly, the ASP-250 limit-fed pigs had serum IGF-I concentrations that were greater (P<.01) than those of the controls. Although the serum IGF-I concentrations of pigs fed the ASP-250-supplemented diet for ad libitum intake were greater than the serum IGF-I concentrations of the pigs limit-fed the ASP-250-supplemented diet, the differences were not significant (P<.08). The ASP-250-fed pigs had higher serum IGF binding protein (BP)-3 concentrations than did their control littermates (P<.003). A time course of antimicrobially induced alterations in serum IGF-I concentrations revealed that the effect of increased serum IGF-I levels in ASP-250-supplemented pigs (P<.02) was observed within 4 d and was maintained throughout the 4-wk study. These findings show that feed intake is not responsible for the increase in serum IGF-I observed with ASP-250 supplementation. Additionally, the antimicrobially induced increase in serum IGF-I concentrations occurs within a few days after initiation of the treatment.

Animals↗