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Biomedical subjects

R J Harmon

Publications and source records attributed to R J Harmon.

At least 55 records · Page 3Linked to original sources
PubMed1995

Psychosocial adaptation of 39 adolescents with sex chromosome abnormalities.

OBJECTIVES: Children with sex chromosome abnormalities (SCA) are known to be at increased risk for neuromotor, language, learning, and behavioral problems, but little is known of psychosocial adaptation of SCA adolescents. This study was conducted to evaluate psychologic characteristics of unselected SCA adolescents, including socialization, educational progress, separation from family, and incidence and severity of psychiatric disturbance. METHODS: Thirty-nine propositi identified through the screening of 40,000 consecutive Denver newborns, including boys with 47,XXY karyotypes and girls with 47,XXX, 45,X, and partial X monosomy, or SCA mosaic karyotypes, have been followed longitudinally into adolescence. Twenty-seven siblings served as controls. Between 12 and 19 years of age, all participated in blind psychiatric interviews and were administered standardized intelligence and achievement tests. RESULTS: SCA propositi demonstrated a mean IQ score 21 points lower than that of control subjects. In addition, lower mean scores were seen on achievement test results as well as lower overall psychosocial adaptation scores and increased incidence of psychiatric disturbance. Depression was the most frequent psychiatric diagnosis. Propositi were more likely to receive special education assistance in high school and were less likely to graduate from high school than were controls. Of the three nonmosaic propositi groups, the 47,XXX girls demonstrated the poorest overall psychosocial adaptation and highest degree of psychiatric disturbance. Mosaic girls were indistinguishable from control subjects. Marked variability was found among all three nonmosaic groups, with some individuals in each group demonstrating relatively strong psychosocial adaptation. CONCLUSIONS: The presence of nonmosaic sex chromosome abnormality increases the risk for impeded cognitive skills, learning abilities, and psychosocial adaptation in adolescence. The factors that allow for stronger adaptation in some of these adolescents include the presence of a stable and supportive family environment. The outlook for adaptation in unselected SCA adults remains uncertain.

Achievement↗
PubMed1994

Genomic fingerprints of Staphylococcus aureus of bovine origin by polymerase chain reaction-based DNA fingerprinting.

Staphylococcus aureus (n = 75) isolated from mammary secretions of cows with subclinical and clinical mastitis from several geographic locations in the USA were examined using polymerase chain reaction-based DNA fingerprinting. DNA fingerprints were produced using a synthetic oligonucleotide primer (5'GTAACGCC3') to produce a distinct spectrum of amplified DNA fragments facilitating a high degree of resolution for differentiating S. aureus strains. PCR-based DNA fingerprinting grouped the 75 S. aureus isolates into 19 distinct profiles. The technique differentiated closely related strains within and between geographic locations. Findings suggest that certain types are found across geographic regions suggesting a common clonal type. Within herd data suggest heterogeneity among subclinical and clinical isolates of S. aureus strains. Compared to existing typing methods, PCR-based DNA fingerprinting is easy to perform and interpret. Use of PCR-based DNA fingerprinting may allow for a more detailed investigation of the epidemiology of S. aureus mastitis in dairy cows.

Animals↗
PubMed1994

Physiology of mastitis and factors affecting somatic cell counts.

Inflammation of the mammary gland that results from the introduction and multiplication of pathogenic microorganisms in the mammary gland is a complex series of events leading to reduced synthetic activity, compositional changes, and elevated SCC. The magnitude and temporal relationships of these responses vary with nutritional status, other animal factors, and the pathogen involved. Because the elevation of SCC is a response to an insult to the mammary gland and is modulated by inflammatory mediators, the major factor influencing SCC is infection status. The effects of stage of lactation, age, season, and various stresses on SCC are minor if the gland is uninfected. Except for normal diurnal variation, few factors other than infection status have a significant impact on milk SCC.

Animals↗
PubMed1993

Mastitis in heifers.

Udder health is typically overlooked but critically important in heifers. Mastitis pathogens of the contagious as well as environmental groups have been implicated in mastitis in heifers. Procedures considered for control of heifer mastitis include prepartum treatment in primigravid heifers, separating preweaned calves to prevent suckling, fly control, and segregation of pregnant heifers from dry cows. Further investigation is needed before general recommendations can be made relative to prepartum treatment of primigravid heifers. An improved understanding of the epidemiology and pathogenesis of heifer mastitis will aid in expanding and improving control measures.

Actinomycosis↗
PubMed1993

Copper status and requirement during the dry period and early lactation in multiparous Holstein cows.

Eighteen multiparous Holstein cows were assigned randomly to three treatments at the beginning of the dry period (8 wk before expected parturition). Treatments were: 1) the basal diet containing 5.5 ppm of Cu (control), 2) the basal diet supplemented with 10 ppm of Cu, and 3) the basal diet supplemented with 20 ppm of Cu. The objectives were to measure the changes of Cu and other trace mineral element concentrations in blood and liver from the onset of the dry period (approximately 8 wk prepartum) to 8 wk postpartum and to assess the requirement of Cu during this time. Liver Cu concentration in the control group declined continuously during the 8-wk dry period, and the nadir occurred at parturition. This decline was prevented by dietary Cu supplementation of 10 or 20 ppm. Liver Cu concentration in the control group started to increase slowly after the dramatic decline. Liver Zn concentration changed cubically as a function of week during the treatment period. Plasma Cu and Zn exhibited a quadratic pattern as a function of week. The plasma Cu concentration was lowest 5 wk prior to parturition.

Animals↗
PubMed1992

The relation between attachment and knowledge of self and mother in one to three-year-old infants.

The relation between attachment to mother and knowledge of self and mother in 2 domains was assessed in 1- to 3-year-old infants. Infants' featural knowledge was measured by featural recognition, name, possession, and gender. In this domain, no difference between the 2 attachment classifications was obtained at 1 year of age, but significant and increasingly large differences between securely and insecurely attached infants were found at 2 and 3 years of age. The second domain measured infants' actions on self and mother in the context of symbolic play. Regardless of age, infants who were securely attached to mother acted on self and mother with greater complexity than did infants who were insecurely attached. Attachment was related equally to the complexity of infants' knowledge of self and mother. These data were discussed in the context of the development of infants' internal working models of attachment and the onset of representational ability.

Child, Preschool↗
PubMed1992

High cortisol concentrations and mediation of the hypogalactia during endotoxin-induced mastitis.

A series of experiments was conducted to define the role of cortisol in the hypogalactia during endotoxin-induced mastitis. In the first experiment, three of six nonmastitic cows were given a continuous infusion of trilostane, a 3 beta-hydroxysteroid dehydrogenase inhibitor that blocks enhanced cortisol synthesis. Trilostane had no effect in these cows. In the second experiment, six midlactation cows were given 10 micrograms of endotoxin in each of two homolateral quarters to induce mastitis. Three of these cows also received trilostane. Increased serum cortisol following endotoxin infusion was blocked by trilostane treatment, whereas serum glucose and rectal temperatures were unaffected. Preventing the cortisol increase failed to reduce hypogalactia in endotoxin-infused or uninfused quarters. Decreases in milk production and increases in measures of mammary inflammation were greater in trilostane-treated cows, indicating that endogenous cortisol may moderate the cow's inflammatory response. In the third experiment, three of six nonmastitic cows were injected intramuscularly with 150 IU of ACTH. Serum cortisol concentration exceeded 70 ng/ml for at least 3 h in cows receiving ACTH. This cortisol concentration, comparable with concentrations found during endotoxin mastitis, did not inhibit milk production. Together, these data demonstrate that the acute cortisol increase does not mediate the hypogalactia associated with endotoxin-induced mastitis.

Animals↗
PubMed1992

Prevalence of Staphylococcus species during the periparturient period in primiparous and multiparous cows.

During a 14-mo period, 77 multiparous and 36 primiparous cows were sampled to determine the prevalence of staphylococci during the periparturient period. Distal streak canal swabs were taken at 14 d prepartum, and foremilk was sampled the first 5 consecutive wk of lactation. Staphylococcus aureus was isolated from 7.6% of quarters of primiparous cows but from only .6% of quarters of multiparous cows at parturition. Prevalence in primiparous cows declined to 3.5% by the wk-1 sampling. Quarter prevalence of coagulase-negative Staphylococcus species prepartum, at parturition, and wk 1 to 5 in primiparous cows was 38.9, 27.8, 15.3, 14.6, 13.2, 15.3, and 14.6%, respectively. In multiparous cows, prevalence at these times was 50.3, 12.3, 6.2, 8.1, 10.7, 7.1, and 8.1%. Staphylococcus chromogenes was the predominant species isolated, accounting for over 50% of the staphylococci isolated at each sampling time. Results suggest that high prevalence of staphylococci isolated prepartum is a reflection of natural skin flora and that a higher postpartum prevalence of these organisms was observed in primiparous cows than in multiparous cows. These data suggest also that the peripartum heifer could be a source of Staphylococcus aureus in the lactating herd.

Animals↗
PubMed1991

Lactating cows become partially refractory to frequent intramammary endotoxin infusions: recovery of milk yield despite a persistently high somatic cell count.

Midlactation cows were infused with 10 micrograms endotoxin in the same two homolateral quarters after each of several consecutive milkings to study the effect of prolonged, endotoxin-induced mastitis on lactational performance. The initial infusion induced an acute response with systemic involvement. Inflammation developed in infused quarters, and milk production declined and milk composition was altered in all quarters. Subsequent infusions failed to induce systemic responses. Furthermore, milk yield and composition in uninfused quarters returned to pre-treatment levels despite further infusions. In infused quarters, milk yield, protein percentage and serum albumin concentration showed partial recovery during the endotoxin infusion period. In contrast, decreased lactose concentration, and increased cell count, N-acetyl-beta-D-glucosaminidase and lactoferrin levels persisted throughout the infusion period. After infusions were stopped, all measurements returned to near pretreatment levels. These data demonstrate that systemic, but not local, responses become refractory to multiple intramammary endotoxin infusions, and that multiple infusions have continued but little progressive or permanent, inhibitory effects on lactational performance despite a persistent mammary leucocytosis.

Acetylglucosaminidase↗
PubMed1991

Endotoxin mastitis in cows milked four times daily.

As part of a project to identify the pathophysiological cause or causes of mastitic hypogalactia, midlactation cows were infused in two homolateral quarters with 10 micrograms of endotoxin while being milked four times daily to resolve better the temporal changes in mammary synthetic activity during endotoxin mastitis. Milk fat was decreased by the first milking (5 h) postinfusion and then recovered rapidly. In contrast, milk yield and the yields of protein and lactose were not significantly inhibited until the second milking, and these yields recovered slowly thereafter. The decline in milk yield by infused quarters was only 20% greater than the decline by uninfused quarters in this experiment. Mammary inflammation developed rapidly in infused quarters as milk serum albumin concentration was maximal at the first milking. Milk SCC and NAGase were also elevated at this time, and maximal levels occurred at milkings 2 to 4. Increased temperature, increased cortisol, and a mild anorexia were apparent at the first milking only. Endotoxin treatment had no effect on serum prolactin or glucose. These data suggest that the delayed hypogalactia is consequent to the mammary inflammation and systemic responses following endotoxin infusion. The results indicate that different pathophysiological events may inhibit synthesis of the different milk components.

Animals↗
PubMed1991

Isolation of Staphylococcus aureus from sites other than the lactating mammary gland.

The body sites of 163 heifers, bedding and feedstuff samples, flies, and hands and nares of the research personnel were sampled in order to determine the sources of Staphylococcus aureus in a dairy herd other than the lactating mammary gland. Lesions on the udder of lactating animals and the air in the milking parlor were also sampled. Staphylococci isolated from bedding samples were identified as to species. Staphylococcus aureus was isolated from all sources examined except flies. An enrichment procedure was necessary for isolating S. aureus from two bedding samples although other Staphylococcus species were present in high numbers. The designation "environmental staphylococci" is proposed for Staphylococcus species that were apparently free-living in the environment.

Air Microbiology↗
PubMed1991

Effect of naturally occurring coagulase-negative staphylococci infections on new infections by mastitis pathogens in the bovine.

Microbiological data from 1123 uninfected quarters and 216 quarters with preexisting coagulase-negative staphylococci infections were analyzed to determine the influence of infection status on subsequent new infection rate. Overall, prevalence of new infections in uninfected quarters was approximately two times that in quarters already harboring a coagulase-negative Staphylococcus infection. New infections by coagulase-negative staphylococci were greater in uninfected quarters than in quarters with preexisting coagulase-negative staphylococci infections. However, no differences were observed between uninfected and infected quarters in number of new infections by major pathogens (Staphylococcus aureus, streptococci, and coliforms). No differences were observed in uninfected or coagulase-negative Staphylococcus-infected quarters in infections with minor pathogens compared with major pathogens. The influence of individual coagulase-negative Staphylococcus species on new infections was also analyzed. However, numbers of existing infections by Staphylococcus species other than Staphylococcus chromogenes were limited. Therefore, the protective capacity of each coagulase-negative Staphylococcus species was difficult to assess. Overall, a significant restriction of bacterial invasion was observed in quarters with a preexisting infection. These results suggest that quarters harboring a coagulase-negative Staphylococcus infection suppress colonization of the mammary gland by mastitis-causing pathogens.

Animals↗
PubMed1991

Effects of copper status on neutrophil function, superoxide dismutase, and copper distribution in steers.

Twelve Holstein steers in a completely randomized block design were fed either a basal diet (concentrate:silage or hay at a DM ratio of 35:65) plus Cu sulfate at 20 ppm of Cu (Cu-supplemented diet) or a basal diet plus ammonium molybdate to obtain 10 ppm of Mo (Cu-depleting diet) on a DM basis in the whole diet for 8 mo. Supplemental Mo was utilized in the Cu-depleting diet to develop a Cu-deficient group. Molybdenum slowly accumulated in the liver in the group fed the Cu-depleting diet. Copper concentrations in the liver and polymorphonuclear neutrophils decreased in the Cu-deficient group compared with the Cu-sufficient group. Plasma Cu concentration did not change during the trial for the Cu-sufficient group. In the Cu-deficient group, plasma Cu concentrations increased during the first 3 mo of the trial, then declined, and remained unchanged for the last 5 mo. Superoxide dismutase activities in red blood cells, polymorphonuclear neutrophils, and whole blood decreased in the Cu-deficient group. Phagocytic capacity was not affected by Cu status, but killing capacity was decreased by low Cu status in the Cu-deficient group by the end of the trial. Glutathione peroxidase activity was unaffected by Cu status. Clinical symptoms of Cu-deficiency were not observed in this trial; there was no evidence of blood hemoglobin or BW gain difference between the two groups. In this study, Cu status affected its distribution in the tissues and related enzyme activities as well as bactericidal function of neutrophils.

Animals↗
PubMed1991

Effects of copper sources and dietary cation-anion balance on copper availability and acid-base status in dairy calves.

Twenty-four Holstein and Jersey calves (14 Holstein), 4 to 11 d of age, were assigned randomly to six treatments in a 2 x 3 factorial arrangement to examine the effects of Cu sources and dietary cation-anion balance on Cu availability and acid-base balance. Treatments were cationic basal diet (20 meq of dietary cation-anion balance on a DM basis), cationic basal diet supplemented with CuO, cationic basal diet supplemented with CuSO4, anionic basal diet (-10 meq), anionic basal diet supplemented with CuO, and anionic basal diet supplemented with CuSO4. Copper sources did not show any effect on growth of calves. The cationic diet increased calf growth compared with the anionic diet at wk 12 of the experiment. Blood pH was increased by the cationic diet in comparison with the anionic diet at wk 8 and 12. Blood pH also was increased by CuSO4 compared with CuO treatment in the early period of the treatment. Blood bicarbonate concentration was decreased by CuO and the anionic diet. Interactions between Cu sources and cation-anion balance were found for blood pH and bicarbonate concentration. Liver Cu concentration was increased by CuSO4 but not by CuO supplementation compared with control. Therefore, CuSO4 was found to be highly available, whereas CuO was a very poorly available source of Cu for young calves.

Acid-Base Equilibrium↗
PubMed1991

Reduced lactational performance following intravenous endotoxin administration to dairy cows.

Nonpregnant lactating cows were given 100 micrograms of endotoxin via the jugular vein to determine effects of intravenous endotoxin administration on mammary inflammation and lactational performance. At the first milking (11 h) posttreatment, milk yield was reduced 33%. Milk fat percentage was elevated at this time, but lactose concentration was decreased. Milk yield and composition returned to pretreatment levels within 2 d. Clinical mastitis was not induced by endotoxin treatment, but milk SCC, NAGase, serum albumin, and lactoferrin were increased by 50%. This increase was small compared with increases during mastitis and may have resulted from lower milk volume. These results support the hypothesis that part of the reduced lactational performance during endotoxin mastitis is mediated by systemic pathophysiological responses and indicate that intravenous endotoxin administration may be a useful model to study adverse effects of infectious disease on lactational performance.

Animals↗
PubMed1991

Suppression of milk production during endotoxin-induced mastitis.

Healthy, midlactation cows were given intramammary infusions of 10 micrograms of endotoxin in two homolateral quarters. Productive, inflammatory, and systemic responses were studied to investigate the pathophysiological effects of mastitis on lactational performance. Endotoxin suppressed milk yield in all quarters of treated cows. A more severe and prolonged suppression occurred in infused quarters compared with uninfused quarters. The fat percentage of milk from all quarters was increased with a greater increase occurring in infused quarters. The protein composition of milk was elevated, and the lactose concentration was depressed in infused quarters. Mammary inflammation--as measured by milk SCC, NAGase, serum albumin, and lactoferrin--was limited to infused quarters. Changes in milk NAGase closely paralleled changes in milk SCC. Daily feed intake was unaffected, and serum glucose levels did not decline following infusion. The lactose concentration of urine increased rapidly after infusion. Reduction in milk yield in all quarters, but varying changes in milk composition in infused versus uninfused quarters suggest that mastitic hypogalactia is mediated by multiple pathophysiological events and is not solely due to inflammatory damage to the mammary epithelium. Part of the reduced lactational performance may result from escape of milk components from the udder into the circulation.

Acetylglucosaminidase↗
PubMed1991

Effect of dietary energy and previous bovine somatotropin on milk yield, mastitis, and reproduction in dairy cows.

Thirty multiparous lactating Holstein cows were blocked according to time of calving and assigned to a 2 x 3 factorial arrangement of treatments in a randomized complete block design to evaluate the effects of two dietary energy concentrations either without or with bST (20.6 mg/d per cow) administered to cows that had not or had received bST during the preceding lactation. Subcutaneous injection of bST began 28 to 35 d postpartum and continued for 39 wk. The dietary energy concentration x bST interaction was not significant for any response variable. Compared with DMI of control cows, DMI was higher for cows receiving bST, being 1.6 and 2.4 kg/d higher for cows receiving bST for one and two lactations, respectively. Milk, fat, and protein yields were higher for cows receiving bST than for controls. Those receiving bST for a second lactation also produced more milk than controls until wk 20; thereafter, milk yields were similar to those of controls. Somatotropin administration had no adverse effect on udder health. Cows receiving bST tended to ovulate less regularly than controls, which may be attributed to their higher milk yield. However, BW gains during lactation were similar for all treatments, indicating that bST-treated cows built energy reserves for the subsequent lactation. Although energy concentrations of the diets had no significant impact on yield, the higher energy diet tended to depress milk fat concentration. Administration of bST to dairy cows for a second, consecutive lactation yielded responses similar for the first 20 wk of the study to those receiving bST for the first time. However, after wk 20, milk yield was less than that by cows receiving bST for the first lactation but similar to that of control cows.

Animals↗