Health concerns of adolescents: impact of family status, sex, family size, and birth order.
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Adolescent↗
Biomedical subjects
K L Smith
Publications and source records attributed to K L Smith.
Enteric viral infections of calves and passive immunity.
At least eight viruses have been identified, four within the last 5 yr, that produce diarrhea and pathological intestinal lesions in experimentally inoculated calves. Coronavirus and rotavirus frequently are associated with the neonatal calf diarrhea syndrome, but the etiologic role of the newly identified viruses is undefined. All diarrheal viruses replicate within small intestinal epithelial cells, resulting in variable degrees of villous atrophy. Immunity against these viral infections, therefore, must be directed toward protection of the susceptible intestinal epithelial cells. Because most of these viral infections occur in calves less than 3 wk of age, passive lactogenic immunity within the gut lumen plays an important role in protection. This report reviews methods of boosting rotavirus antibody responses in bovine mammary secretions and analyses of passive and active immunity in calves supplemented with colostrum and challenged by rotavirus. Results indicate rotavirus immunoglobulin G1 antibodies in colostrum and milk were elevated after intramuscular and intramammary vaccination of pregnant cows with an Ohio Agricultural Research and Development Center rotavirus vaccine but not after intramuscular immunization with a commercial rota-coronavirus vaccine. Feeding colostrum from intramuscular plus intramammary immunized cows to newborn calves challenged by rotavirus prevented diarrhea and shedding of rotavirus.
Animals↗
Environmental pathogens and intramammary infection during the dry period.
Rate of coliform and streptococcal intramammary infection during the dry period was studied in 168 dry periods. Coliform infection rate was influenced by stage of dry period, parity, and season during which dry periods occurred. Effects of dry cow therapy, immunization, or induced inflammation on coliform infection rate were minimal. Coliform infections originating in the first 50% of the dry period and persisting to lactation were predominantly other than Escherichia coli, whereas the majority originating in the last 50% of the dry period and persisting to lactation were Escherichia coli. Duration of streptococcal infections was greater than coliform infections. Dry cow therapy reduced streptococcal infection rate, and the effect was exerted primarily during the first 25% of the dry period. Effects of parity and season were not significant and likely masked by the positive effects of dry cow therapy. Results support the contention that all quarters of all cows should be dry treated for maximum reduction of new streptococcal infection during the dry period. Results suggest that methods other than conventional dry cow therapy are required for control of coliform infection during the dry period and streptococcal infection during the latter half of the dry period.
Animals↗
Environmental mastitis: cause, prevalence, prevention.
Rate of intramammary infection by coliform bacteria and species of streptococci other than Streptococcus agalactiae (environmental pathogens) was studied in a dairy herd in total confinement. Rate was higher during the dry period than during lactation and increased progressively as parity increased. Rate was maximal during summer and coincided with maximum exposure to coliforms in bedding. Streptococcal infections were longer than coliform. Approximately 59% of streptococcal infections and 69% of coliform infections were present for 30 lactation days or less. Percent quarters infected by day of year varied between .7 and 3.0% for coliform bacteria and between 1.6 and 4.7% for streptococci. Approximately 81% of coliform infections and 53% of streptococcal infections during lactation were clinical. Clinical cases were highest during the first 76 days of lactation and during summer. Only 6.7% of coliform infections resulted in acute coliform mastitis, and all acute cases were during summer or early lactation. Dry cow therapy reduced rate of streptococcal infection during the early dry period but was without effect during the prepartum period. There was no effect of dry cow therapy on coliform infection rate during the dry period. Problems associated with prevalence and control of environmental mastitis were discussed.
Animals↗
In vitro growth of mastitis-associated streptococci in bovine mammary secretions.
Cell-free, fat-free mammary secretions were tested in vitro for ability to support growth of streptococci associated with mastitis. Secretions were obtained prior to drying off, during the dry period, at calving, and during lactation from four cow treatment groups. Treatment groups were dry cow therapy, dry cow therapy and mammary glands subjected to induced inflammation 7 d post-drying-off, no dry cow therapy and no induced inflammation, no dry cow therapy but mammary glands subjected to induced inflammation. Growth of Streptococcus uberis, Streptococcus faecalis, and Streptococcus agalactiae in secretions from nonlactating glands was unaffected by induced inflammation. Growth of Streptococcus bovis was significantly inhibited in secretion obtained 14 d after induced inflammation. Dry cow therapy had no effect on streptococcal growth in secretion obtained 7 d after therapy. Streptococcal growth was greatest in secretions from involuted glands, and there was little or no evidence for growth inhibitory factors in cell-free, fat-free secretions obtained during the dry period. Milk from lactating glands inhibited streptococcal growth, and the inhibitory factor was presumptively identified as lactoperoxidase. Apolactoferrin, immunoglobulin, or both had little effect on streptococcal growth.
Animals↗
Inhibition of mastitic bacteria by bovine milk apo-lactoferrin evaluated by in vitro microassay of bacterial growth.
An in vitro microassay was developed to evaluate antimicrobial properties of bovine apo-lactoferrin. The growth of coliform, staphylococcal, and streptococcal bacterial strains in a defined synthetic medium was inhibited by bovine apo-lactoferrin (.5 to 30.0 mg/ml). Addition of iron-saturated lactoferrin to the synthetic medium did not inhibit growth of test strains. Inhibition by apo-lactoferrin was greater for coliform than Gram-positive strains for all concentrations of apo-lactoferrin evaluated. No concentration of apo-lactoferrin proved bactericidal for either coliform or Gram-positive strains. Inhibition of two coliform strains by apo-lactoferrin (10 mg/ml) was abolished by addition of ferric iron to the assay system, indicating an iron-dependent nature of apo-lactoferrin induced inhibition of bacteria. Bicarbonate supplementation of the growth system containing apo-lactoferrin (1 mg/ml) increased inhibition of three coliform strains by apo-lactoferrin. Addition of increasing concentrations of citrate (2.0 mg/ml) to an assay system containing apo-lactoferrin (5 mg/ml) resulted in a concomitant reduction of growth inhibition of three coliform strains. These data indicate a potential relationship between the molar ratio of citrate to lactoferrin of the lacteal secretion and its capacity to inhibit coliform strains associated with mastitis.
Animals↗
Effect of vitamin E and selenium supplementation on incidence of clinical mastitis and duration of clinical symptoms.
Incidence of clinical mastitis and duration of clinical symptoms for complete lactations were evaluated for 80 cows randomly assigned to one of four groups: vitamin E supplemented- and selenium injected, selenium injected, vitamin E supplemented, and controls. Vitamin E supplementation and selenium injection were during the dry period. Log-linear analysis of incidence data revealed a significant 37% reduction of clinical mastitis by vitamin E. Incidence was not affected by selenium alone, nor was there any evidence for interaction of vitamin E with selenium on incidence. However, duration of clinical symptoms (calendar months clinical/quarter lactating) was reduced by 46% for the selenium group, 44% for the vitamin E group, and 62% for the vitamin E-selenium group as compared to controls. We conclude that dairy cow diets deficient of vitamin E may elevate incidence of clinical mastitis. Selenium deficiency may result in greater duration of clinical symptoms, and selenium may interact with vitamin E. Coliform bacteria and species of streptococcus other than Streptococcus agalactiae were isolated from 70% of the clinical cases.
Animals↗
Biochemical and antibacterial properties of bovine mammary secretion during mammary involution and at parturition.
Mammary secretions from four Holstein Friesian cows were collected during late lactation, early involution, and early in subsequent lactation. Changes of pH, concentration of serum albumin, immunoglobulin G, citrate, lactoferrin, and number of leukocytes in secretions were typical of milk from glands undergoing these physiological transitions. Whey prepared from a cow's secretions was evaluated for its capacity to inhibit growth of Escherichia coli, 60-Lilly, and a coliform strain isolated from mammary secretions of that cow. Wheys from different glands of the same cow differed markedly in their capacity to inhibit growth of coliforms. Inhibition of both strains by the wheys increased significantly during the dry period and was maximal in wheys collected day 15 of the dry period and at parturition in the subsequent lactation. The coliform strain isolated from a specific cow was inhibited more than Escherichia coli, 60-Lilly, by whey from the specific cow. Inhibition of the cow-specific coliform strain by the day 15 whey was reduced significantly after addition of ferric iron or sodium citrate. Addition of excess ferric iron or citrate to wheys collected at parturition did not alter significantly their inhibitory capacity within cow. However, reduction of growth inhibition was significant when data from the four cows were pooled.
Animals↗
Immune response of pregnant cows to bovine rotavirus immunization.
Fifteen pregnant Holstein cows were freely assigned to 3 experimental groups (5 cows in each group). Cows in group I were inoculated IM and intramammarily (IMm) with Ohio Agricultural Research and Development Center (OARDC) tissue culture-propagated modified-live Nebraska calf diarrhea bovine rotavirus with added adjuvant (OARDC vaccine-immunized cows). Group II cows were given IM injections of a commercial modified-live rotavirus-coronavirus vaccine (commercial vaccine-immunized cows), and the remaining 5 cows were noninoculated controls (group III). Rotavirus antibody in colostrum and milk was mainly associated with immunoglobulin (Ig)G1, and less so with IgG2, IgA, and IgM, as analyzed by the enzyme-linked immunosorbent assay (ELISA), using monospecific anti-bovine IgG1, IgG2, IgM, and IgA sera. In serum, the rotavirus antibody was distributed almost equally between IgG1 and IgG2. The same relationships appeared in both immunized and nonvaccinated cows. All OARDC vaccine-injected cows had virus-neutralization (VN) and ELISA IgG1 rotavirus antibody titers in serum and mammary secretions at significantly increased levels (at least 100-fold; P less than 0.05) compared with the titers in groups II (commercial vaccine-immunized cows) and III (controls). Serum, colostrum, and milk antibody titers from these latter 2 groups did not differ statistically. The ELISA IgG2, IgA, and IgM rotavirus antibody titers also were significantly greater in mammary secretions from OARDC vaccine-immunized cows than in groups II and III cows. There was a high correlation between ELISA IgG1 and VN rotavirus antibody titers for all samples tested (r = 0.97, P less than 0.001), but ELISA IgG1 antibody titers were consistently higher than VN titers. The ELISA IgG1 and VN antibody titers of milk samples collected from cows 30 days after parturition were higher from the OARDC vaccine-immunized cows (ELISA IgG1, geometric mean titer (GMT) = 3,511; VN GMT = 1,689) than were titers from the group II cows (ELISA IgG1 GMT = 39; VN GMT = 33) or group III cows (ELISA IgG1 GMT = 21; VN GMT = 19). These results indicate that IM plus IMm immunization of pregnant cows, using modified-live bovine rotavirus with added adjuvant, may significantly enhance serum, colostrum, and milk rotavirus antibody titers, whereas IM vaccinal inoculation of pregnant cows with a commercial modified-live rotavirus-coronavirus vaccine may not.
Adjuvants, Immunologic↗
Properties of neutrophils recruited into inflammatory foci with homologous or heterologous antigen in immunized ewes.
Studies were undertaken to determine functional properties of neutrophils attracted into involuted mammary glands of Staphylococcus aureus--immunized ewes by soluble antigens prepared from S. aureus (homologous antigen) or from Bacillus cereus (heterologous antigen). The ewes were immunized with an S. aureus vaccine known to stimulate synthesis of cytophilic IgG2 antibody, and the inflammatory responses were elicited 4-8 weeks later by infusing homologous antigen into one gland and heterologous antigen into the other. Inflammatory cells were collected at 2, 4, and 8 h postinfusion. The magnitude of the cellular responses was similar in both glands with high proportions of viable neutrophils. There were no significant differences between neutrophil populations from each gland for proportions of cells bearing cytophilic immunoglobulin, although the proportions of cytophilic immunoglobulin-positive cells from both glands were lower in 2-h exudates than in 4-h or 8-h exudates. In invitro phagocytosis assays using 3H-labeled S. aureus and B. cereus no differences could be detected between the two populations of neutrophils in terms of phagocytic efficacy using a range of bacteria-neutrophil ratios and various opsonizing treatments.
Animals↗
Passive immunity to bovine rotavirus in newborn calves fed colostrum supplements from immunized or nonimmunized cows.
Colostrum was collected and pooled from each of five cows in three experimental groups: group I cows received intramuscular and intramammary inoculations of adjuvanted modified live Ohio Agricultural Research and Development Center rotavirus vaccine; group II cows were injected intramuscularly with a commercial modified-live rota-coronavirus vaccine; and group III cows were uninoculated controls. Pooled colostrum from group I cows had higher (P less than 0.05) enzyme-linked immunosorbent assay (ELISA) immunoglobulin G (IgG1) and virus neutralization (VN) rotavirus antibody titers (ELISA IgG1 = 2,413,682; VN = 360,205) than did colostrum from group II (ELISA IgG1 = 8,192; VN = 4,395) or group III cows (ELISA IgG1 = 5,916; VN = 2,865). The antibody titers of these last two colostrum pools did not differ (P greater than 0.05). Samples of these colostrum pools were fed as daily supplements (percent [vol/vol] in cow's milk infant formula) to 28 newborn, unsuckled, antibody-seronegative, male Holstein calves. Eight calves received no supplemental colostrum. The calves were orally challenged with virulent bovine rotavirus and monitored daily for diarrhea and fecal rotavirus shedding. Diarrhea and rotavirus shedding occurred in the eight calves fed no supplemental colostrum and persisted longest in this group. The pooled colostrum from group I cows protected eight of eight calves from both rotavirus diarrhea and shedding when fed as a 1% supplement. The pooled colostrum from neither group II nor group III cows protected 12 other calves against rotavirus diarrhea or shedding when fed at the same concentration (1%). Six rotavirus-challenged calves fed 0.1% supplemental colostrum from group I cows and two calves fed 10 and 50% supplemental colostrum from control cows displayed partial passive immunity, exemplified by delayed onset and shortened duration of rotavirus-associated diarrhea and virus shedding.
Animals↗
Inhibition of pulmonary macrophage function by airway mucus.
As a model for the interaction between macrophages and mucus in the tracheobronchial tree, we incubated sheep alveolar macrophages in vitro with and without airway mucus from the same animal and tested their phagocytic function and rates of general protein synthesis. Airway mucus was obtained by tracheal suction after previous subcutaneous injection of the sheep with pilocarpine (0.5 mg/kg) and subsequently diluted. Pulmonary macrophages were obtained by saline lavage through a balloon-tipped fiber-optic bronchoscope. In incubated attached macrophages, phenylalanine incorporation into protein was inhibited 51% by mucus (P less than 0.001). Phagocytosis of 1.09-microns latex particles was inhibited 75% by mucus at nonsaturating levels of particles (P less than 0.001) and by 47% at saturating levels of particles (P less than 0.001). Inhibitory activity for protein synthesis and phagocytosis was retained in the 104,000 g supernatant fraction of whole mucus (sol), while the gel fraction inhibited phagocytosis only. This difference did not appear to be related to physical factors. We conclude that diluted airway mucus interferes with pulmonary macrophage function as assessed by rates of general protein synthesis and phagocytosis.
Animals↗
Mastitis control: a discussion.
Methods of mastitis control that are effective against Streptococcus agalactiae and Staphylococcus aureus have been developed and proven successful. These control procedures, however, are not as effective against the environmental pathogens. Environmental pathogens are predominantly the coliform bacteria and species of streptococci other than Streptococcus agalactiae. The total extent of their present involvement in mastitis is not well documented, and this is due in part to differences in the nature of infection by environmental pathogens compared to Streptococcus agalactiae and Staphylococcus aureus infections. Concern regarding the importance of environmental pathogens in mastitis is increasing. This concern is based, first, on current trends of dairy cattle housing and management that increase exposure to teat ends to environmental pathogens and, second, on a reduction of prevalence of Streptococcus agalactiae and Staphylococcus aureus infected quarters. The latter is a result of the effectiveness of postmilking teat end disinfection and dry cow therapy. Development of equally effective control methods for the environmental pathogens will be an important area of future mastitis research.
Animal Husbandry↗
Confrontation: a new dimension in nutrition counseling.
The advanced counseling skill of confrontation is described. Possession of this skill allows the practicing dietitian to point out clients' discrepant behaviors or thought patterns which obstruct progression toward goals. Confrontation is a positive and constructive act, not a negative, punitive one. When conducted properly, it enhances the working relationship between client and dietitian.
Counseling↗
Milk yield and secretion composition following intramammary infusion of colchicine.
Twenty-five lactating dairy cows were in a split block design to investigate effects of intramammary colchicine infusion on milk yield and composition. Right udder halves of 15 cows were infused with colchicine while left udder halves received no infusion. Ten cows received no infusion in either right or left udder halves. At 24 h postintramammary colchicine infusion, milk yield decreased 38.5% in treated halves and 9.3% in control halves. Udder halves of uninfused cows had an 8.7% reduction. Milk from treated halves compared to untreated halves had elevated somatic cells, serum albumin, and pH. Citrate and the molar ratio of citrate to lactoferrin were lower. Lactoferrin and immunoglobulin G did not differ between infused and uninfused halves; however, they increased in treated halves postinfusion as compared to preinfusion. Serum albumin and citrate increased, and the index of selective accumulation of immunoglobulin G decreased in left halves. Control cows did not differ.
Animals↗
Bovine mammary involution following intramammary infusion on colchicine and endotoxin at drying off.
Effects of intramammary infusion of colchicine, endotoxin, and colchicine in combination with endotoxin on mammary involution were studied on 25 dairy cows in late lactation. Both quarters of right udder halves were infused at or near drying off while left udder halves received no infusion. Samples of mammary secretion were obtained 1 day prior to drying off, at drying off, and .5, 1, 2, 3, and 7 days post drying off. Mammary secretion obtained during the early dry period from udder halves infused with colchicine or colchicine and endotoxin at or near drying off had elevated somatic cells, lactoferrin, serum albumin, immunoglobulin G, and pH as compared to left untreated udder halves. Citrate, molar ratio of citrate to lactoferrin, and the index of selective accumulation of immunoglobulin G were lower in infused than uninfused udder halves. Fluid volume removed from udders at 7 days involution was 40% less in udder halves infused with colchicine or colchicine and endotoxin as compared to uninfused udder halves. Intramammary infusion of colchicine and endotoxin at drying off accelerates bovine mammary involution.
Animals↗
Nonantibiotic approach in control of bovine mastitis during dry period.
Twenty cows were used to determine effectiveness of a nonantibiotic method for control of intramammary infection during the dry period. Right mammary quarters of cows were infused with colchicine, endotoxin, or both at 1 day prior to or at the end of lactation. Left quarters were uninfused controls within group. Samples (n = 1105) of foremilk were obtained aseptically from quarters for bacteriological analysis. Quarters were sampled during the last week of lactation, early nonlactating period, prepartum, at parturition, and 1 and 2 wk postpartum. Primary pathogens isolated were esculin + streptococci, coagulase + staphylococci, and coliform bacteria. Isolation of primary pathogens was reduced 50% in right infused quarters during the 1st wk of involution as compared to left uninfused quarters. Thirteen of 80 quarters were infected at the end of lactation (6 right and 7 left), and 20 of 80 quarters (9 right and 11 left) were infected at calving. Sixteen of the 20 infections at calving were new during the dry period. Treatment reduced infection during early involution but failed to prevent new infection during the remainder of the dry period.
Animals↗
Failure of chloroform to induce chromosome damage or sister-chromatid exchanges in cultured human lymphocytes and failure to induce reversion in Escherichia coli.
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Benzo(a)pyrene↗