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Biomedical subjects

J S Hogan

Publications and source records attributed to J S Hogan.

86 records · Page 5Linked to original sources
PubMed1987

Effects of teat dipping on intramammary infections by staphylococci other than Staphylococcus aureus.

Effects of intramammary infections in herds 1) either not teat dipping or postmilking teat dipping with either 2) linear dodecyl benzene sulfonic acid, 3) chlorhexidine, or 4) iodophor containing products were determined. Duplicate quarter foremilk samples were collected once from all lactating cows in 16 herds, four for each practice. Mean percentage of quarters infected with Staphylococcus species other than Staph. aureus was 11.0 in herds not teat dipping and 7.2 in herds teat dipping. Prevalence of Staphylococcus species intramammary infections in herds teat dipping with linear dodecyl benzene sulfonic acid was comparable to herds not teat dipping and greater than in herds using chlorhexidine and iodophor. The predominant Staphylococcus species in herds not teat dipping was Staph. epidermidis (37.1%). Staphylococcus hyicus constituted 48.5% of total Staphylococcus species intramammary infections in herds teat dipping and 12.4% in herds not teat dipping. Differences were not observed among SCC for quarters infected with different Staphylococcus species. Application of germicidal teat dips appeared to have selectively altered both prevalence and distribution of Staphylococcus species intramammary infections.

Animals↗
PubMed1987

Growth inhibition of mastitis pathogens by long-chain fatty acids.

Staphylococcus aureus, Staphylococcus hyicus, Streptococcus agalactiae, and Corynebacterium bovis were tested for sensitivity to long-chain fatty acids predominant in teat canal keratin. Antibacterial activity of free fatty acids on each bacterial species was measured after 12 and 24 h in chemically defined media. Polyene C18:2 and C18:3 acids were bactericidal to each species at less than or equal to 10(5) ng/ml-1. The most bacteriostatic saturated fatty acids were C12 and C14. Streptococcus agalactiae growth was inhibited more by fatty acids after 24 h than after 12 h. No incubation time effect on growth responses of other species was determined. Polyoxyethylenesorbitan monooleate had a neutralizing effect on the bactericidal activity of polyene acids on C. bovis. Corynebacterium bovis were unable to grow in synthetic media containing individual free fatty acids as the sole source of preformed fatty acids. A relationship between bacterial species commonly isolated from bovine teat canals with resistance to fatty acids predominant in keratin was not evident.

Animals↗
PubMed1987

Growth responses of Staphylococcus aureus and Streptococcus agalactiae to Corynebacterium bovis metabolites.

Staphylococcus aureus and Streptococcus agalactiae growth responses to metabolites of Corynebacterium bovis cultured in media containing polyoxyethylenesorbitan monolaurate, monooleate, or trioleate and milk were determined. Filter sterilized metabolites of 48-h C. bovis cultures in synthetic media were added to cultures of Staph. aureus and Strep. agalactiae. Staphylococcus aureus and Strep. agalactiae were inoculated into 12-h C. bovis milk cultures. Growth responses of Staph. aureus and Strep. agalactiae were not affected by C. bovis metabolites of synthetic media. Staphylococcus aureus growth was inhibited during logarithmic and stationary phases in milk containing mixed cultures of C. bovis compared with growth in pure Staph. aureus cultures. Streptococcus agalactiae growth curves were similar in pure and C. bovis mixed cultures. Fatty acid compositions were not different in sterile milk and milk containing bacterial cultures. Growth responses of Staph. aureus and Strep. agalactiae were not related to concentration of C. bovis metabolites or fatty acid content of media in which C. bovis were cultured.

Corynebacterium↗
PubMed1986

Fatty acid composition of bovine teat canal keratin.

Keratin from 507 excised teats was pooled, separated into three samples, and analyzed for fatty acid composition of extracellular and intracellular lipids. Mean weight of keratin collected per teat canal was 8.97 mg. Extracellular lipids were recovered in petroleum ether. Intracellular lipids were extracted in chloroform: methanol (2:1, vol/vol) solution. Average keratin wet weight of extracellular and intracellular lipid fractions were 37.1 and 21.9 mg/g, respectively. Polar and nonpolar lipids were present in both fractions. Predominant fatty acids in extracellular and intracellular lipids were C16, C18:1, and C18. Extracellular lipids contained greater concentrations of C4 to C18:1 fatty acids than did intracellular lipids. Percent of total fatty acid weight comprised by each of C4, C10, C12 and C14 was also significantly greater in extracellular than intracellular fractions. Intracellular lipids contained a greater concentration and percent total fatty acid content comprised by C18:2 than extracellular lipids. Data suggest lipids accessible at the keratin interface are in part of milk fat origin.

Animals↗
PubMed1986

Comparison of isotonic and hypertonic fluids in resuscitation from hypovolemic shock.

Hypertonic electrolyte solutions provide effective fluids for resuscitation of burn patients and concurrent replacement of hemorrhage. Infusion of mannitol has also been advocated as a means of increasing cardiac output in acutely ill patients. Pigs which were bled to one-third of their blood volume were used in this random study of resuscitation with Ringer's lactate solution (RL), hypertonic saline solution (HSL) and RL with mannitol added (HMR) to give the same osmolality as HSL. Smaller volumes of the hyposmolar solution than of RL restored blood pressure and cardiac output. RL and HSL restored and maintained cardiac output more effectively than HMR. At 24 hours, HSL maintained blood pressure most effectively.

Animals↗
PubMed1986

Comparison of four test procedures to identify Staphylococcus aureus isolated from bovine intramammary infections.

A comparison was made between conventional tube coagulase, macrocupsular coagulase, latex agglutination, and miniaturized biochemical test systems for identification of Staphylococcus aureus of bovine origin. A total of 303 gram-positive, catalase-positive cocci of bovine origin were tested. Agreement between each pair of 4-hour tube coagulase, macrocupsular coagulase, latex agglutination, and miniaturized biochemical test results within isolates was greater than 95.0. Seventeen (5.6%) isolates were test negative for 4-hour tube coagulase, but test positive for 24-hour tube coagulase. Thirteen (76.5%) of these isolates were identified as S hyicus, 3 were S aureus, and 1 was not identified.

Animals↗
PubMed1985

A personal computer system for testing gas exchange, heart, lungs, ventilatory pump.

This paper reports the development of a computer system for testing gas exchange and lung function in the ICU. The essence of the system is a software package that uses an IBM personal computer for data processing and analysis. Front end hardware is modular, as is software, so that portions or all of the system can be used. The system provides measurements of lung mechanics work, functional residual volume, spirometry, oxygen uptake, carbon dioxide output, lung water, blood gas interpretation, hemodynamics. Reports are provided by standard data base manager and so are easily customized.

Computers↗
PubMed1985

Effects of Corynebacterium bovis infection on susceptibility to major mastitis pathogens.

Experimental challenge procedures were used to study infectivity and virulence of Corynebacterium bovis. Challenge procedures using Staphylococcus aureus (Newbould 305) and Streptococcus agalactiae (McDonald 44) were used to study effects of Corynebacterium bovis infections on superinfection with major pathogens. Rate of infection under experimental challenge conditions was significantly greater with Corynebacterium bovis than previously observed for Staphylococcus aureus or Streptococcus agalactiae. Principal location of Corynebacterium bovis colonization appeared to the teat canal region, although the organism was isolated from 75% of the teat cisterns by puncture technique. Quarters with Corynebacterium bovis infections were more resistant to infection by Staphylococcus aureus than bacteriologically negative quarters. Quarters infected with Corynebacterium bacterium bovis were approximately 8.5-fold more susceptible to Streptococcus agalactiae infection than negative quarters. Somatic cell counts were doubled in negative quarters that developed Corynebacterium bovis infections; the geometric mean was 2.4 X 10(5).

Animals↗
PubMed1984

Efficacy of an iodine backflush for preventing new intramammary infections.

Efficacy of an iodine backflush system for reducing new intramammary infection was tested in two 11-wk trials. Forty cows in each trial were paired by breed, age, stage of lactation, and intramammary infection status. Each pair was assigned randomly either to a group milked with clusters that were reverse flushed with water, 25 ppm iodine, water and air or to a group milked with clusters receiving no backflush treatment between cows. Backflushing clusters reduced infections caused by Corynebacterium bovis and coagulase-positive staphylococci in both trials. However, backflushing clusters produced no clear advantage for reducing new infections with coagulase-negative staphylococci, Gram-negative bacilli, or streptococci (species other than Streptococcus agalactiae). No differences in somatic cell counts between experimental groups were observed. Teat cup liners and teat ends were swabbed after 120 and 1200 milkings/liner. Total microbial counts were significantly greater for liners that were not backflushed than from backflushed liners at each swabbing. However, no differences were significant between groups for mean teat end microbial counts in either trial.

Animals↗
PubMed1980

Mechanism of death in massive fluid infusion.

To determine the effects of infusion of large volumes of crystalloid, a series of dogs was subjected to intravenous injection of oleic acid and moderate hypovolemic shock for 1 hour. They were then resuscitated with 50 cc/kg of Ringer's lactate over 1 hour in one group and 2 hours in the other. Eight of nine receiving the fast infusion died during the first 2 days, and seven of eight receiving the slow infusion lived for the full 3 days of the study. The dogs that died all had large intrapulmonary shunts and gross pulmonary edema at autopsy. Both groups received the same total amount of fluid. No differences in vascular pressure or cardiac function large enough to explain the differences were found. The critical difference was the rate of fluid infusion. The high-permeability pulmonary edema appears to have been aggravated by a transitent pulmonary overperfusion induced by fast infusion of fluid.

Animals↗
PubMed1978

Fluid overload and post-traumatic respiratory distress syndrome.

A series of dogs was given massive fluid infusions at two dose levels, 60 cc/kg and 100 cc/kg. The dogs were prepared in three ways: shock induced by bleeding; intravenous injection of oleic acid; and combined oleic acid injection and shock. The studies showed that type of injury was a more important determinant of lung dysfunction than the fluid dose. Shock animals were not hurt by fluid infusion; in oleic acid-injected dogs, the fluid infusion magnified the effect of oleic acid. When shock, oleic acid, and high fluid dose were combined, all animals died. The animals that died had high pulmonary artery diastolic pressures.

Animals↗
PubMed1976

The effects of carbon dioxide on pulmonary mechanics in hyperventilating, normal volunteers.

Transpulmonary pressure, air flow, and end-tidal carbon dioxide levels were measured in normal human volunteers during hypocapnic, eucapnic, and hypercapnic hyperventilation. Respiratory rate and tidal volumes were well matched at a minute ventilation of 52 L. on three inspired gas mixtures: 21 per cent oxygen and 79 per cent nitrogen; 5 per cent carbon dioxide, 21 per cent oxygen and 74 per cent nitrogen; and 12 per cent carbon dioxide, 21 per cent oxygen and 67 per cent nitrogen. Respiratory rate, tidal volume, lung compliance, resistance, and resistive work per liter were calculated with a digital computer. In 13 experiments in 7 normal volunteers, no net bronchoconstriction or bronchodilatation was observed when eucapnic hyperventilation was compared to hypocapnic or hypercapnic hyperventilation. During hyperventilation of this degree, a change in bronchomotor tone owing to alteration in arterial or alveolar PCO2 either does not occur or else is masked by other reflexes or mechanical factors acting on the bronchi.

Adult↗