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Biomedical subjects

C W Heald

Publications and source records attributed to C W Heald.

At least 19 recordsLinked to original sources
PubMed2000

A computerized mastitis decision aid using farm-based records: an artificial neural network approach.

A computer module was developed and tested that used field survey and Dairy Herd Improvement Association (DHIA) data to broadly classify bacterial causes of mastitis in dairy herds. Further development of the computer model could aid interpretation of DHIA data by dairy record processing centers and herd consultants. This diagnostic module was developed with an artificial neural network, a technology that processes complex data in a manner similar to human brain function. Information describing herd management practices, quarter milk samples, and monthly DHIA data was collected from Pennsylvania dairy herds with moderate to high somatic cell counts. This information was used to develop or train an artificial neural network model that discriminated among four categories of bacterial organisms (contagious, environmental, no significant growth, and other) associated with clinical and subclinical mastitis. After training the model, new DHIA and management data were presented to the model to assess its ability to classify bacteriological etiology. When the artificial neural network was used, the probabilities of diagnosing the bacteriologic status from three randomly selected cow groups and from new untested herds ranged from 57 to 71%. Performance of the artificial neural network model was best in herds with higher frequency of minor and contagious pathogens. Prediction results for the same test data with linear discriminant analysis were less successful, ranging from 42 to 57%.

Animals↗
PubMed1985

Effect of automatic backflushing on number of new intramammary infections, bacteria on teatcup liners, and milk iodine.

Effect of an automatic iodine (15 ppm) backflushing system on incidence of new intramammary infections, teatcup liner bacterial populations, and milk iodine was tested in a herd free of Streptococcus agalactiae and with a low prevalence of Staphylococcus aureus. In an 11-mo trial, backflushing was applied to teatcups that milked the right half of the udder; the left half served as control. Clawpieces were divided into left and right halves with each having a milk outlet. Postmilking teat dipping was discontinued. All lactating cows in the University herd were used, averaging 154 with normal attrition and additions of new individuals as they calved. Backflushing reduced numbers of staphylococci recovered from liners by 98.5% and Gram-negative bacteria by 99.5% as compared with unflushed liners. Backflushing significantly reduced new infections caused by Corynebacterium bovis. However, there was no effect on incidence of new infections by staphylococci, streptococci, or coliforms. Iodine concentrations averaged 243 micrograms per liter in milk from control quarters and 486 micrograms from backflushed udder halves. Interior surface cracking was more severe in backflushed teatcup liners than in control liners. These results do not justify the use of backflushing in a herd with low prevalence of contagious pathogens.

Animals↗
PubMed1984

Morphometric effect of prostaglandin E1 and F2 alpha on lactating bovine mammary tissue in vitro.

Mammary explants from six lactating cows were incubated for .17, 4, 8, and 12 h in medium containing prostaglandin E1 or prostaglandin F2 alpha tromethamine salt at 0, 1, 10, or 50 micrograms/ml to determine if prostaglandins alter tissue structure. Explants were fixed, dehydrated, embedded in plastic resins, and sectioned at .5 to 1.0 mu. Tissue area was partitioned by light microscopy into normal, damaged, or debris epithelial; normal or debris lumenal; or stromal areas. All tissue samples exhibited signs of deterioration as incubation progressed. Prostaglandin E1 treatment maintained more secretory epithelium and resulted in less epithelial debris and lumenal debris than controls. Prostaglandin F2 alpha-treated tissue had less epithelial debris and normal lumenal area than tissue receiving no prostaglandin during the limited incubation. The three concentrations of prostaglandins studied did not identify optimal prostaglandins for mammary tissue incubated but indicated concentrations below 1 microgram prostaglandin E1 or F2 alpha/ml should be studied. The response of mammary tissue to prostaglandin was affected by donor milk production. Increases of normal epithelial area were correlated with decreases of damaged and debris areas. Prostaglandins E1 and F2 alpha appeared to be beneficial to healthy mammary tissue incubated under limited conditions.

Alprostadil↗
PubMed1984

Influence of ration physical form and nitrogen availability on ruminal morphology of growing bull calves.

Male Holstein calves were fed complete diets containing three physical forms (ground and chopped hay and all concentrate) and three rumen degradable protein percent. Calves were slaughtered at 20 wk of age. Weights of reticulorumen with and without contents wee recorded. Proportions of mucosa and muscle and gross morphology were determined on excised rumen wall. From nine additional calves rumen epithelial tissue was obtained for light microscopic examination of papillae to determined length, width, surface area, and morphological condition. Weights of reticulorumen with contents were heaviest for calves fed ground hay and tissue weights heaviest for calves fed concentrate. Ruminal content volume was greater for calves fed diets containing hay compared to all concentrate. Hay contents tended to be drier and less dense than concentrate contents. Ruminal epithelial lining was heavier in concentrate-fed and had more mucosa to muscle compared to rumen of calves fed ground or chopped hay. However, papillary length, number of papillae per field, and surface area/field was greater in calves fed hay. Morphological abnormalities of the rumen epithelium occurred more frequently in calves fed concentrate. Reticulorumen measures were unaffected by degradable protein percent. Absorptive capacity of calves fed all concentrate diets decreased compared to calves fed diets with 40% hay.

Abomasum↗
PubMed1984

Relationships between somatic cell counts and milk production.

The relationship between Dairy Herd Improvement program test-day milk yield and somatic cell counts in milk was analyzed in 34 dairy herds over 3 yr. Estimates of this relationship were more accurate when somatic cell counts were transformed to natural logarithms rather than actual. For 67,707 observations, test-day milk yield decreased with increasing somatic cell count. The decrease of milk yield for second and later lactations, as somatic cell count increased, was greater than for first lactations. When herds were partitioned according to herd milk production (greater than 7700, 6500 to 7700, and less than 6500 kg/yr), decrease of milk yield was linear with increasing somatic cell counts for herds averaging below 7700 kg milk. Regressions were linear, quadratic, and cubic for both parity groups in herds with high production, over 7700 kg/yr. Quarter samples were composited for each cow and cultured. Percentage of infected cows increased as somatic cell counts increased with greater infection rates above 400 X 10(3).

Animals↗
PubMed1983

Effect of the intramammary device on milk infection status, yield, and somatic cell count and on the morphological features of the lactiferous sinus of the bovine udder.

Twenty primiparous heifers were fitted intramammarily with polyethylene coils in both quarters of one random right or left udder half at 5 days after parturition. Foremilk samples were collected and udder-half milk yields were measured at the afternoon milking on days - 1, 3, 7, and 14 and on every 14th day for 8 months after the device was inserted. Three weeks after the heifers were fitted with the intramammary device, 6 were euthanatized for gross observation of devices and tissues and cytologic evaluation of the gland cistern epithelium. There were significantly fewer bacterial isolations (P less than 0.01) and less clinical mastitis (P less than 0.05) in treated quarters than in the control quarters. Coagulase-negative staphylococci were isolated at frequencies of 0 and 15.2% for treated and control quarters. The reduction in isolation frequency for treated, compared with control, quarters was less marked with other organisms. Intramammary devices in no way interfered with the milking process. Milk yields per milking were 4.2 kg for treated udder halves compared with 4.4 kg for control halves; however, this 0.2 kg difference was not significant. Mean milk somatic cell counts, as determined by electronic counter, were 34 X 10(3) and 81 X 10(3) cells/ml for control and treated quarters (P less than 0.05). Mean bovine serum albumin values were 0.160 and 0.175 mg/ml for control and treated udder halves (P less than 0.05), indicating an increased capillary permeability due to the device. Quantitative morphologic analysis of gland cisterns showed a significant (P less than 0.05) change toward a single layer of epithelial cells in treated quarters compared with a double layer in control quarters.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Cells in local reaction to experimental Staphylococcus aureus infection in bovine mammary gland.

Blood cells infiltrating secretory parenchyma of bovine mammary glands experimentally infected with Staphylococcus aureus were studied. Quantitative cytology demonstrated lymphocytes, plasma cells, monocytes, macrophages, and neutrophils more numerous in infected than control quarters and more prevalent at 10 than 2 days postinfection. These cells preferentially infiltrated the zone of the infected quarter closest to the gland cistern. Lymphocytes tended to remain associated with the epithelium, and many were within spaces between swollen secretory cells. Monocytes entered between alveolar epithelia and appeared to mature into macrophages and migrate to lumina where they contained milk constituents, degenerate neutrophils, and cocci. Neutrophils were observed primarily in alveolar lumina where many degenerated. Some neutrophils in various stages of degeneration also were lodged in the alveolar epithelium. Plasma cells were prevalent in infected tissue stroma, and most contained Immunoglobulin A which became more numerous as infection progressed. Our observations provide quantitative and ultrastructural information on cell types in bovine mastitis and are consistent with the concept of a cellular immune response to Staphylococcus aureus invasion.

Animals↗
PubMed1982

Migration of polymorphonuclear leukocytes into the bovine mammary gland during experimentally induced Staphylococcus aureus mastitis.

The process of neutrophilic polymorphonuclear leukocyte (PMN) migration in the bovine mammary gland during experimental Staphylococcus aureus challenge was studied using light and electron microscopies. The PMN were observed in various stages of margination in capillary lumens and migration into perivascular spaces. In infected tissue showing little evidence of epithelial damage, numerous PMN were accumulated in the perivascular space and aligned against the epithelial basal lamina, but not in the alveolar lumen. Other areas of infected tissue showed progressive tissue degeneration (autophagic vacuoles, vesiculation of endoplasmic reticulum, and cellular debris in the luminal milk) with the appearance of numerous PMN in lumens. The PMN were observed between the basal end of adjacent epithelial cells having intact tight junctions, but were never seen traversing the junctional complex. Some PMN lying between intact epithelial cells appeared to have ingested fat globules before entering the lumen. Although the mechanism by which PMN crossed tight junctions was not explained, alveoli with a portion of the epithelium sloughed off were frequently seen. The PMN appeared to be entering alveoli in large numbers at these damaged sites. There was also marked PMN infiltration in tissue from teat and gland cisterns of S aureus-infected quarters.

Animals↗
PubMed1981

Concentrations of glucocorticoids, bovine serum albumin, and somatic cells in mastitic milk.

Milk glucocorticoids, bovine serum albumin, and somatic cells were measured during experimental mastitis. Six cows were allotted evenly into injected and control groups. Injected cows received a single intramammary infusion of .5 mg sterile Escherichia coli endotoxin in a quarter chosen at random. Control cows were untreated. Milk quarter samples were taken from all cows at both milkings and 9 h following midnight milking 1 day prior to glucocorticoid concentrations occurred 9 h postinjection and were 17.5 ng/ml (+/- 10.2), and 4.4 ng/ml (+/- 2.3) in injected and noninjected quarters of the same cows. In injected cows glucocorticoid concentrations returned to baseline within 36 h. Glucocorticoids in control quarters were .4 ng/ml (+/- .3). Peak bovine serum albumin was 27.8 ng/ml (+/- 22.8) and .56 bg/ml (+/- .09) in injected and noninjected quarters in the same cows as compared to a baseline of .2 mg/ml (+/- .04) in control cows. In injected quarters, bovine serum albumin remained elevated for 4 days, and somatic cells were elevated for 6 days after injection. Glucocorticoids, bovine serum albumin, and somatic cells were elevated markedly in injected quarters, and unlike concentrations of bovine serum albumin and somatic cells, elevated glucocorticoids in injected quarters were short lived.

Animals↗
PubMed1981

Histopathologic response of the bovine mammary gland to experimentally induced Staphylococcus aureus infection.

At 2 and 10 days after Staphylococcus aureus mastitis was induced in dairy cattle, mammary tissue from 2 zones in infected quarters was morphometrically compared with similar zones in contralateral control quarters. In comparison with control tissue, infected tissue exhibited more interalveolar stromal area, reduced alveolar luminal area, and more damaged and involuted alveolar epithelial area. These changes appeared more advanced at 10 days than at 2 days after infection was induced, indicating that by day 10, glandular parenchyma was losing secretory potential. Quarter zones differed greatly in the responses to infection. Parenchyma taken from a zone of an infected quarter close to the glandular part of the lactiferous sinus appeared to undergo involution more rapidly than a zone further from the sinus. Involuted parenchyma displayed reduced secretory activity, diminished luminal areas, and abundant connective tissue. A portion of nonsecretory epithelia taken from involuted areas of a zone close to the glandular part of the sinus stained for presence of immunoglobulin A.

Animals↗
PubMed1981

Effect of cortisol on the bactericidal function of the bovine milk neutrophil in vitro.

Milk neutrophils and Staphylococcus aureus were incubated for 2 hours at a 1:1 ratio in sterile common milk media with various cortisol concentrations. Milk neutrophils were harvested twice at a weekly interval from 6 cows. Mean percentage of phagocytosis (+/- SD) was 20.2 +/- 10.1, 34.6 +/- 21.0, 27.2 +/- 17.8, 30.3 +/- 21.4, and 23.9 +/- 16.7 for treatments with 0, 20, 40, 60, and 10,000 ng/ml. Mean percentage of kill was 12.7 +/- 12.4, 14.9 +/- 11.2, 11.2 +/- 10.9, 12.1 +/- 12.3, and 6.6 +/- 10.3, for 0, 20, 40, 60, and 10,000 ng/ml treatments. Mean percentage of efficiency of kill, a measure of the ability of neutrophil to kill phagocytized bacteria, was 49.5 +/- 40.0, 53.5 +/- 38.8, 46.9 +/- 38.0, 34.9 +/- 35.2, and 27.3 +/- 32.8, respectively. The pharmacologic concentration (10,000 ng/ml) of cortisol depressed kill, whereas physiologic concentrations (20, 40, and 60 ng/ml) of cortisol increased phagocytosis, but did not affect kill.

Animals↗
PubMed1979

Morphometric study of experimentally induced Staphylococcus bovis mastitis in the cow.

Comparisons were made of bovine mammary tissue at 12 and 24 hours after 5,000 colony-forming units of Staphylococcus aureus 305 was injected into the mammary parenchyma with control tissue from the contralateral udder half. A mild form of staphylococcal mastitis was induced routinely. Generally, S aureus was found in udder tissue removed centrally from the site of injection. Varied degrees of tissue damage were found in infected quarters from alveolar epithelium without damage (similar to control) to extremely swollen epithelium which were typical of cells undergoing disruption. Infected tissues frequently displayed areas of swollen stroma and areas of diminished alveolar lumens. Cellular debris was often found in lumens, and neutrophils frequently filled the alveolar lumen in areas of greatest damage. Thus, a parenchymal injection of bacteria induced early forms of staphylococcal mastitis at the alveolar level.

Animals↗
PubMed1978

Cytological effects of hormones and plasma on bovine mammary tissue in vitro.

Mammary explants from two heifers pretreated with oestradiol and progesterone were cultured for 96 h with various combinations of hormones and calf plasma to identify the complement causing mammary tissue development in vitro in the cow. Initial tissue histology, determined by quantitative morphological analysis, was maintained by incubation with insulin, cortisol, oestrogen and progesterone; enlarged lumina were observed after treatment with insulin and cortisol. Lactogenesis was induced in vitro by insulin, cortisol and prolactin, enhanced by adding oestrogen and progesterone at the doses used here and further stimulated by the addition of plasma. The most highly developed mammary alveoli were characterized by an increased luminal area with lipid and stainable secretion, epithelia with large lipid droplets in the apical cytoplasm and a limited stromal area. In a second experiment, samples of plasma were collected from two cows, successfully induced to lactate, on days 6, 15, 17, 19 and 21 after treatment with oestradiol and progesterone. Mammary gland explants from five heifers pretreated with oestradiol and progesterone in vivo were cultured with insulin and cortisol plus these plasma samples (30%, v/v) to test for changes in lactogenic activity. All plasma samples were found equally beneficial in promoting tissue differentiation. These experiments show that low concentrations of ovarian steroids synergize with prolactin at the level of the mammary epitherlium and suggest that other plasma components aid the development of bovine mammary epithelium in vitro.

Animals↗
PubMed1977

Effect of prepartum milk removal on quantitative morphology of bovine lactogenesis.

The effect of prepartum milking on bovine mammary histology and milk composition was studied in five Holstein cows. One udder half was milked twice daily starting 10 days before the estimated calving date. On udder half was not milked until 2 days postpartum when all quarters were milked and two tissue samples per quarter were taken for morphological analyses. Lactose, casein, and fat concentrations differed from prepartum-milked to postpartum-milked quarters (.82, -1.44, and 3.29%). Quarters milked prepartum were more developed: mature epithelium 24.8%, immature epithelium - 8.9%, total epithelium 15.6%, stroma -24.8%, and alveolar lumen 8.5%. Most alveolar cells in prepartum-milked halves had prominent rounded basal nuclei, hypertrophied secretory vesicles, and a mixed array of lipid droplets. Cells within alveoli were morphologically similar. Secretory epithelial cells from postpartum-milked glands had irregular randomly located nuclei, indistinct Golgi, variable lipid content, and less cytoplasm. These differences demonstrate the importance of prepartum-product removal on secretory cell development and subsequent milk production.

Animals↗
PubMed1975

Histology of induced bovine lactogenesis.

Nine cycling nonlactating dairy cows were treated hormonally to induce lactation with progesterone, estradiol-17beta, and dexamethasone. Mammary tissue biopsies were taken on days 18, 21, and 23 after initiation of treatment (different three cows for each period). First milking was initiated on day 21 in the latter two groups. Mean differences in tissue development (percent area) between day 18 and 23 were, epithelium + 11.1%, stroma -25.9%, alveolar lumen + 13.9%, adipose + 1.58%, duct - 974%, and + 15 nuclei/alveolar section. On day 18 epithelia containing small lipid droplets predominated but were replaced with mixed lipid droplets by day 23. Epithelia day 18 had elongated dark staining nuclei. Epithelia on day 23 had spherically shaped nuclei often containing several nucleoli and an increased cytoplasmic/nuclear ratio. Marked histological development occurred from 18 to 23 days after initiation of treatment. Mammary tissue development in nongravid hormonally treated animals was equal to or greater than 2-wk-prepartum tissue but less than 2-day-prepartum tissue for natural lactations.

Adipose Tissue↗