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K C Davis

Publications and source records attributed to K C Davis.

At least 19 recordsLinked to original sources
PubMed2004

The impact of anti-tobacco industry prevention messages in tobacco producing regions: evidence from the US truth campaign.

BACKGROUND: Adolescents who live in tobacco producing regions may not respond favourably to anti-industry ads. OBJECTIVE: To examine whether state level involvement in tobacco production appears to limit the effectiveness of anti-industry ads to prevent tobacco use among adolescents in the USA. DESIGN: Time trend analyses were done using repeated cross sectional data from six waves of the Legacy Media Tracking Survey, which were collected between 1999 and 2003. SETTING AND PARTICIPANTS: 28,307 adolescents, ages 12-17 years, were classified as living in: tobacco producing states (TPS) (n = 1929); non-tobacco producing states (non-TPS) with low tobacco control funding comparable to TPS (n = 5323); non-TPS with relatively high funding (n = 15,076); and non-TPS with established anti-industry ad campaigns (n = 5979). MAIN OUTCOME MEASURES: Reactions to anti-industry ads; strength of anti-industry attitudes/beliefs; changes in anti-industry attitudes/beliefs over time. RESULTS: Ad reactions did not differ by state type. Multivariate adjusted time trend analyses indicated significant, comparable increases in anti-industry attitudes/beliefs since the onset of the truth campaign, in both TPS and non-TPS. Mediation analyses indicated that these increases were due, in part, to campaign exposure. CONCLUSIONS: Adolescents who live in tobacco producing regions appear to be as responsive to anti-industry ads as their counterparts in non-tobacco producing regions. This study provides further evidence for the effectiveness of such ads.

Adolescent↗
PubMed2003

Analysis of environmental Escherichia coli isolates for virulence genes using the TaqMan PCR system.

AIMS: To assess the presence of virulence genes in environmental and foodborne Escherichia coli isolates using the TaqMan PCR system. METHODS AND RESULTS: Three TaqMan pathogen detection kits called O157:H7, StxI and StxII were used to investigate the presence of virulence genes in Escherichia coli isolates. All 54 foodborne E. coli O157:H7 isolates showed expected results using these kits. Ninety (15%) of 604 environmental isolates gave positive amplification with an O157:H7-specific kit. TaqMan PCR amplification products from these 90 isolates were analysed by agarose gel electrophoresis, and 90% (81 of 90) of the environmental samples contained the expected PCR product. Sixty-six of these 90 were chosen for serotyping tests and only 35% (23 of 66) showed agglutination with both anti-O157 and anti-H7 antibodies. Further ribotyping of 16 sero-positive isolates in an automated Riboprinter did not identify these to be O157:H7. Multiplex PCR with primers for eaeA, stxI and stxII genes was used to confirm the TaqMan results in 10 selected environmental isolates. CONCLUSIONS: All three TaqMan pathogen detection kits were useful for virulence gene analysis of prescreened foodborne O157:H7 isolates, while the O157:H7-specific kit may not be suitable for virulence gene analysis of environmental E. coli isolates, because of high false positive identification. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability to rapidly identify the presence of pathogenic E. coli in food or environmental samples is essential to avert outbreaks. These results are of importance to microbiologists seeking to use TaqMan PCR to rapidly identify pathogenic E. coli in environmental samples. Furthermore, serotyping may not be a reliable method for identification of O157:H7 strains.

Bacterial Typing Techniques↗
PubMed2001

Lactate dehydrogenase release assay from Vero cells to distinguish verotoxin producing Escherichia coli from non-verotoxin producing strains.

The Vero cell assay presently used for virulence testing of verotoxigenic Escherichia coli (VTEC) requires at least 48-96 h where cytotoxicity effects are examined under a microscope. Here, a complimentary rapid assay was developed that measures endogenous lactate dehydrogenase (LDH) release from Vero or HEp-2 cells as an indicator of cytotoxicity. Toxin preparations from 24 VTEC strains induced 36-89% LDH from Vero cells and 15-62% LDH from HEp-2 cells in 12-16 h. A verotoxin-positive but enterohemolysin negative strain also showed a similar cytotoxicity effect. In contrast, three VT-negative strains caused only 13-16% LDH from Vero cells and 1-7% LDH from HEp-2 cells. Five presumptive E. coli isolates from naturally contaminated food and clinical sources did not induce significant LDH release from either cell lines. PCR analysis confirmed the presence of vt1 or vt2 genes in E. coli showing positive LDH values. Similarly, RiboPrinter analysis confirmed and identified the test strains as E. coli except for two meat isolates, which were identified as Hafnia alvei. Cytopathic effects of toxin preparations from VTEC revealed severe lysis, vacuole formation and death in Vero cells and multiple vacuoles and cell elongation in HEp-2 cells. The colorimetric cytotoxicity assay described here can provide quantitative data for determining the virulence potential of verotoxigenic E. coli in 12-16 h.

Animals↗
PubMed1998

Effects of dietary vitamin E supplementation during late pregnancy on lamb mortality and ewe productivity.

OBJECTIVE: To determine the effect of feeding vitamin E to ewes during late pregnancy on lamb mortality and ewe productivity. DESIGN: Prospective study. ANIMALS: 1,302 mature Rambouillet and Targhee ewes. PROCEDURE: During a 3-year period, approximately 430 ewes/y were randomly allocated to 2 groups; supplement-group ewes were fed additional vitamin E and control-group ewes were not. Beginning approximately 3 weeks before the first expected lambing date, ewes were fed 2.3 kg (5 lb) of alfalfa-grass hay/d and 0.23 kg (0.5 lb) of barley-based pellets/d with or without supplemental vitamin E. Pellets that were supplemented contained 1,450 mg of DL-alpha-tocopherol acetate/kg (658 mg/lb) of feed and provided an additional 330 IU of vitamin E/ewe/d. Selenium was incorporated into a trace mineral salt and fed free choice to all ewes throughout pregnancy. RESULTS: Supplemental vitamin E had no effect on ewe weight, body condition score, fertility, or prolificacy. In ewes that lambed in the early part of the lambing season, vitamin E supplementation significantly reduced lamb mortality, compared with no supplementation (12 vs 17%, respectively). Consequently, supplement-group ewes had significantly greater total body weight of lambs per ewe at the time of weaning, compared with control-group ewes. Differences were not observed between ewe groups in lamb mortality or total body weight of lambs per ewe at the time of weaning when ewes lambed during the late part of the lambing season. CLINICAL IMPLICATIONS: If ewes are fed additional vitamin E3 weeks before parturition, those that lamb in the early part of the lambing season may have low lamb mortality and, thus, higher total body weight of lambs per ewe at the time of weaning.

Animals↗
PubMed1998

Heterosis and breed additive effects for Hereford, Tarentaise, and the reciprocal crosses for calf traits.

Records from 595 straightbred Hereford (HH), straightbred Tarentaise (TT), and reciprocal-cross (HT) females, randomly mated to HH, TT, or HT bulls, were analyzed for estimates of heterosis and breed additive effects for calf traits that included birth weight (BWT), calving difficulty (DIFF), prebreeding (PRE) and postbreeding (PST) weight, weaning weight (WWT), weaning condition score (WCS), weaning hip height (WHH), and preweaning average daily gain (ADG). The statistical model included year, age of dam, sex, regression on age at time of measurement, and regressions for the genetic effects of breed individual, breed maternal, breed grandmaternal, individual heterosis, and maternal heterosis. Breed effects were coded to reflect TT- HH differences. Age at the time of measurement, year, age of dam, and sex were significant for most traits. Individual breed effects were important (P < .05) for BWT, PRE, PST, WCS, and WHH but not for WWT, resulting in lower weights, less condition, and taller animals for TT. Maternal breed effects did not influence BWT, but they were important ( P < .05) for PRE, PST, WWT, WCS, WHH, and ADG. Grandmaternal effects were only important for BWT and ADG. Individual and maternal heterosis were important (P < .05) for most traits measured, resulting in increased calf size, weight, and body condition.

Animal Feed↗
PubMed1996

Magnetic field characteristics of electric bed-heating devices.

Measurements of the flux density and spectra of magnetic fields (MFs) generated by several types of electric bed heaters (EBH) were made in order to characterize the MFs to which the fetus may be exposed in utero from the mother's use of these devices. Data on MPs were gathered from more than 1,300 in-home and laboratory spot measurements. In-home measurements taken at seven different positions 10 cm from the EBHs determined that the mean flux density at the estimated position of the fetus relative to the device was 0.45 microT (4.5 mG) for electric blankets and 0.20 microT (2.0 mG) for electrically heated water beds. A rate-of-change (RC) metric applied to the nighttime segment of 24 h EMDEX-C personal-dosimeter measurements, which were taken next to the bed of volunteers, yielded an approximate fourfold to sixfold higher value for electric blanket users compared to water-bed heater users. These same data records yielded an approximate twofold difference for the same measurements when evaluated by the time-weighted-average (TWA)MF exposure metric. Performance of exposure meters was checked against standard fields generated in the laboratory, and studies of sources of variance in the in-home measurement protocols were carried out. Spectral measurements showed that the EBH's measured produced no appreciable high-frequency MFs. Data gathered during this work will be used in interpreting results from a component of the California Pregnancy Outcome Study, which evaluates the use of EBHs as a possible risk factor in miscarriage.

Abortion, Spontaneous↗
PubMed1996

Genetic components for milk production of tarentaise, hereford, and tarentaise x hereford cows.

The objective of this study was to estimate genetic components for milk production of Hereford (HH), Tarentaise (TT), and Hereford x Tarentaise or Tarentaise x Hereford (HT) cows under range conditions at the Northern Agricultural Research Center, Havre, MT. Milk production of 494 cow-calf pairs was estimated by the weigh-suckle-weigh procedure from 1989 to 1994. Milk production and cow and calf weights were measured at 40 d (early) and 120 d (late) of lactation. The mating scheme was a 3 x 3 design in which HH, HT, and TT cows were mated with HH, HT, and TT sires, producing calves that were varying percentages of Hereford and Tarentaise. Data were analyzed by least squares procedures according to a model that included year, age of cow, sex of calf, linear regression on calf age, and linear regressions on coefficients that coded for various genetic components. These genetic components were breed individual, breed maternal, breed grand maternal, individual heterosis (calf heterosis), and maternal heterosis (cow heterosis). Coefficients for genetic components were such that breed effects estimated TT-HH and regressions on heterosis values estimated the full effect of heterosis. The breed individual genetic component was significant only for calf early and late weights; Tarentaise calves were lighter. Breed maternal was significant for most traits, and these effects were positive for milk production (2.16 and 3.77 kg/d for early and late, respectively) and calf weights but negative for cow weights. Individual heterosis was not significant for early milk production but was significant for late milk production (1.05 kg/d) and calf weights (2.3 and 8.1 kg for early and late, respectively). Maternal heterosis was significant for most traits and increased early milk production (1.25 kg/d), calf weights (4.5 and 5.8 kg for early and late, respectively), and cow weights (18.1 and 6.0 kg for early and late, respectively).

Analysis of Variance↗
PubMed1995

Tarentaise and Hereford breed effects on cow and calf traits and estimates of individual heterosis.

Preweaning and weaning records on 457 calves and weights and milk production of their dams were used to evaluate breed of dam effects, breed of sire effects, and individual heterosis effects. Hereford and Tarentaise dams were mated to Hereford and Tarentaise sires and calves were born from 1987 to 1991. Calf traits were birth weight, proportion calving difficulty, weaning weight, weaning height, weaning weight:height ratio, and condition score at weaning. Cow traits were milk production four weights during the year, weight changes, height at weaning, condition score, ratio of calf weight:cow weight, proportion calved and weaned, and calf weaning weight per cow exposed to breeding. Breed of sire was nonsignificant for all traits except calf hip height, but breed of dam was significant for calf weaning weight and condition score, late milk production, change in milk production, and the cow traits of all weights, condition score, weight:height ratio, and ratio of calf weight:cow weight. Least squares means for Hereford and Tarentaise dams, respectively, were 216 and 236 kg for calf weaning weight, 6.2 and 9.3 kg for late milk production, 559 and 507 kg for cow weight at weaning, 6.0 and 4.9 for cow condition score, and .39 and .47 for ratio of calf weight at weaning:cow weight at weaning. Heterosis was significant for birth weight (1.05 kg, 3%, P = .01), weaning weight (11.0 kg, 5%, P = .01), and condition score (.13, 2%, P = .06). Thus, Hereford dams weighted more and had higher levels of condition, whereas Tarentaise dams produced more milk late in lactation and weaned heavier calves.

Analysis of Variance↗
PubMed1994

Magnetic-field flux density and spectral characteristics of motor-driven personal appliances.

Flux density and spectral measurements were carried out on magnetic fields generated by several types of motor-driven personal appliances used near the body. Among the units tested were several for which the average flux densities, as determined at the surfaces of the appliance, exceeded 0.4 mT. Time-rates-of-change (dB/dt) for several units exceeded 1000 T/s, and several units exhibited high-frequency components in the low-MHz range. Use of such appliances, although normally of short duration, can represent exposure to magnetic fields of relatively high flux density, which may also have high-frequency components. Compared to other household and commercial sources of magnetic fields, those generated by certain motor-driven personal appliances may represent a significant contribution to time-weighted average exposure and may represent an important source of local induced currents in the body. Furthermore, high-frequency transients that represent only a minor contribution to time-weighted average exposure may generate significant instantaneous induced currents.

Calibration↗
PubMed1994

Design and fabrication of well confined uniform magnetic field exposure systems.

Exposure systems that provide good magnetic field uniformity, minimum stray fields, and minimal heating, vibration, and hum, as well as capability for true sham exposure in which current flows in the coils, are needed to determine rigorously the biological effects of weak magnetic fields. Designs based on acrylic polymer coil support structures and twisted pair bifilary coil windings were employed to fabricate several different systems for the exposure of laboratory animals and cell cultures to magnetic fields. These systems exhibit excellent performance characteristics in terms of exposure field uniformity, stray field containment, and exposure field cancellation in the sham exposure mode. A custom-written computer program was used to determine the best arrangement for coils with regard to field uniformity in the exposure volume and stray field containment. For in vivo exposures, modules were made up of four Merritt four-coil sets, built into a single structure and positioned to form an octapole with fields directed in the horizontal plane. For in vitro applications, two different coil configurations were selected to produce the vertical fields required. A quadrupole system, comprising modules consisting of two Merritt four-coil sets arranged side by side to limit stray fields, was built as a prototype. In the second configuration, one Merritt four-coil set was positioned inside the other to form a concentric coil set. In both in vitro systems, exposure chambers were connected to remote commercial incubators in order to reduce ambient magnetic fields in the exposure volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylates↗
PubMed1994

Life cycle evaluation of five biological types of beef cattle in a cow-calf range production system: I. Model development.

Data collected during a 10-yr study at the Northern Agricultural Research Center (NARC), Havre, MT were used in construction of a simulation model to evaluate production systems using different breed groups. Five dam breed groups, straightbred Hereford (HH), 50% Angus-50% Hereford (AH), 25% Simmental-75% Hereford (1S3H), 50% Simmental-50% Hereford (1S1H), and 75% Simmental-25% Hereford (3S1H), were studied. The simulated system was a northern range cow-calf production system with spring calving and fall weaning. Replacement heifers were purchased and all calves were marketed at weaning. All nonpregnant females were sold in the fall. Statistical analyses of the data yielded input values (least squares means for breed group x age x sex subclasses) for cow and calf weights, pregnancy rate, dystocia, and calf survival. Pregnancy, dystocia, calf survival, calf weights, and cow weights were simulated stochastically. Energy requirements for maintenance, growth, gestation, and lactation were predicted from equations adapted from the literature based on body weight, frame size, sex, and breed group. Economic inputs and outputs were computed by accounting for variable input expenses and output revenues associated with animal performance and fixed costs associated with range management. Simulated measures of system performance included measures of energy conversion, break-even prices, and profit.

Animal Feed↗
PubMed1994

Life cycle evaluation of five biological types of beef cattle in a cow-calf range production system: II. Biological and economic performance.

Results from a 10-yr study of five dam breed groups in a range beef production system were used as inputs to a simulation model to evaluate life cycle biological and economic performance. Dam breed groups were straightbred Herefords (HH), Angus-Hereford and Simmental-Hereford F1 crosses (AH and 1S1H), 75% Hereford-25% Simmental (1S3H), and 25% Hereford-75%. Simmental (3S1H). Biological measures were number of lifetime matings, calves weaned and kilograms of calf weight sold per cow exposed, and metabolizable energy (ME) consumed per kilogram of calf weight sold and per kilogram of total weight sold. Simulated economic measures were break-even steer prices, total production costs, net profit per cow exposed, and net profit for a ranch of fixed size. The HH and 3S1H dams consumed the least ME per kilogram of total weight sold yet had the highest steer break-even prices and lowest profits. The F1 dams yielded consistently higher profits than other dam breed groups. Breed group rankings were not sensitive to prices paid for hay or calf prices relative to cow prices. Regression techniques were used to estimate maternal heterosis and maternal breed substitution effects from the simulated data. Maternal heterosis effects were large and highly significant for all measures of system performance and were desirable for all traits except ME/kilogram of total weight sold. Maternal heterosis for net profit was nearly $70.cow-1.yr-1 and $20,400/yr for a ranch of fixed size (2,700 AUM range forage). Maternal breed substitution effects were generally much smaller than heterosis effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1986

Altered immunity in hemophilia correlates with the presence of antibody to human T-cell lymphotropic virus type III (HTLV-III).

Twenty-nine heterosexual patients with hemophilia were investigated with histories, physical examinations, laboratory evaluations of immune function, delayed hypersensitivity skin tests, and assays for antibody to human T-cell lymphotropic virus type III (HTLV-III). Sixteen patients were HTLV-III antibody positive and 13 were HTLV-III antibody negative. No patient had the acquired immune deficiency syndrome (AIDS). Patients who had antibody to HTLV-III had received significantly more units and lots of factor concentrates in the preceding 5 years than those who did not have antibody. HTLV-III antibody-positive patients had significantly fewer total T cells (Leu-1 positive) and significantly fewer helper T cells (Leu-3 positive) than HTLV-III negative patients. Antibody-positive patients also had increased amounts of IgG and decreased thymidine incorporation in response to concanavalin A in vitro. There were no differences in in vitro lymphocyte responses to phytohemagglutinin (PHA), pokeweed mitogen, Candida, tetanus, or purified protein derivative (PPD), no significant impairments of gamma interferon or interleukin-2 (IL-2) production, and no anergy. Ten patients with antibody to HTLV-III had immunologic studies repeated 1 year after the original evaluation. A significant increase was seen in suppressor (Leu-2-positive) T cells but not in total T-cell or helper T-cell numbers, helper/suppressor ratios, or T-cell functional assays. We conclude that the immune abnormalities in hemophiliacs are the result of contact with HTLV-III but that these abnormalities may remain stable over prolonged periods.

Adult↗
PubMed1986

Possible role of diet in delayed pressure urticaria--preliminary report.

Late cutaneous reactions preceded by an immediate wheal-and-flare reaction have been described after allergen skin testing, intradermal 48/80 injection, and skin testing with heterologous antihuman IgE. We report the finding of delayed cutaneous reactions after prick food skin testing in a subgroup of five patients with delayed pressure urticaria. This subgroup is also defined by symptomatic clearing after fasting. We demonstrate a correlation of food challenge with skin test response in this same subgroup. Some patients who had previously required prednisone for control of urticaria were able to be managed without it while they were receiving the exclusion diet. In addition, their pressure symptoms and challenge disappeared while they were receiving the restricted diet. These findings suggest that an underlying food sensitivity may be an important precipitating factor in some patients with delayed pressure urticaria.

Adult↗
PubMed1985

Interleukin-2 production by persons with the generalized lymphadenopathy syndrome or the acquired immune deficiency syndrome.

We measured production of interleukin-2 (IL-2) by phytohemagglutinin-stimulated peripheral blood mononuclear cells from 27 heterosexual persons, 43 asymptomatic homosexual men, 34 homosexual men with generalized lymphadenopathy syndrome (GLS), and 21 patients with acquired immune deficiency syndrome (AIDS). Asymptomatic heterosexual and homosexual subjects produced comparable amounts of IL-2, but 8 of 11 AIDS patients with opportunistic infections and two of three AIDS patients with both opportunistic infections and Kaposi's sarcoma failed to produce detectable amounts of IL-2; all seven AIDS patients with only Kaposi's sarcoma produced IL-2. The titer of IL-2 produced by the AIDS patients correlated with the percentage of helper T lymphocytes (Leu 3a+ cells) but not with the percentage of suppressor T lymphocytes (Leu 2a+ cells). This observation is interpreted as indicating that failure to produce IL-2 by AIDS patients is most likely due to depletion of IL-2-producing cells, although an abnormality of T-cell function has not been excluded. In addition, three of eight AIDS patients who did not produce IL-2 produced supernatants that inhibited growth of IL-2-dependent cells in the presence of IL-2. These observations suggest that measurement of endogenous IL-2 production may be important in selecting patients for therapy with IL-2.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Late cutaneous reactions in patients with delayed pressure urticaria.

Late cutaneous reactions ( LCRs ) have been described in patients after allergen skin testing, skin testing with heterologous anti-human IgE, autologous skin-blister fluid, and, variably, after 48/80 injection. We report our results of skin testing patients with delayed pressure urticaria ( DPU ), chronic urticaria, and normal volunteers with histamine and 48/80. All patients with DPU had LCRs after 48/80. No patients in either of the other groups developed LCRs . This may be a clue to pathogenic mechanisms involved in DPU .

Adult↗
PubMed1984

The hypocomplementemic urticarial-vasculitis syndrome: therapeutic response to hydroxychloroquine.

We report a patient with hypocomplementemic urticarial-vasculitis syndrome. This case illustrates the continuum between urticaria and purpura characteristic of hypocomplementemic urticarial-vasculitis syndrome. Clq precipitin was demonstrated in the patient's serum and in the diethylaminoethylcellulose-ion exchange fraction containing only IgG. A skin biopsy specimen of urticarial and purpuric lesions demonstrated leukocytoclastic vasculitis and granular deposition of C3 and Clq in the basement membrane with IgA, IgM, C3, and Clq in postcapillary venules. Serial total hemolytic complement activity and Clq determinations were performed, and the response to several treatment regimens is presented. Symptomatic and serologic improvement was observed only with hydroxychloroquine.

Adult↗