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Biomedical subjects

M Drennan

Publications and source records attributed to M Drennan.

10 recordsLinked to original sources
PubMed2003

The effect of abrupt weaning of suckler calves on the plasma concentrations of cortisol, catecholamines, leukocytes, acute-phase proteins and in vitro interferon-gamma production.

The objective of this study was to examine the effect of abrupt weaning (inclusive of social group disruption and maternal separation) on the physiological mediators of stress and measures of immune function. Thirty-six male and 36 female calves (Limousin and Charolais crosses), habituated to handling, were blocked by sex, weight, and breed of dam and randomly assigned, within block, to either a control or abruptly weaned group. Animals were separated into the respective treatment groups at 0 h. Calves were bled at -168, 6 (males only), 24, 48, and 168 h after weaning, and the behavioral reaction of calves to handling was scored. Cortisol, catecholamine (not sampled at -168 h), acute-phase protein concentrations, and in vitro interferon-gamma production and neutrophil:lymphocyte ratio were measured. The effects of weaning, calf sex, time, and their respective interactions were described. Disruption of the established social group at 0 h increased (P < 0.001) the plasma cortisol concentration and neutrophil:lymphocyte ratio and decreased the leukocyte concentration (P < 0.001) and the in vitro interferon-gamma response to the mitogen concanavalin-A (P < 0.001) and keyhole limpet hemocyanin (P < 0.001) for weaned and control animals compared with -168 h. There was no effect of weaning or sex on the behavioral reaction of calves to handling. Plasma cortisol and adrenaline concentrations were not affected by weaning or sex. Plasma noradrenaline concentration was influenced by weaning x sex (P < 0.05) and time x sex (P < 0.05). The response increased for male calves with weaning and increased with each sampling time after weaning. For heifers, the response was not affected by weaning and plasma concentrations decreased at 168 h after weaning. There was no effect of weaning or sex on leukocyte concentration. The neutrophil:lymphocyte ratio increased after weaning (P < 0.01) and was affected by sex (P < 0.05). Weaning decreased (P < 0.05) the in vitro interferon-gamma response to the antigen keyhole limpet hemocyanin. There was a time x weaning x sex (P < 0.05) interaction for fibrinogen concentration but no effect of treatment on haptoglobin concentration. Abrupt weaning increased plasma cortisol and noradrenaline concentrations that were accompanied by attenuation of in vitro interferon-gamma production to novel mitogen and antigen complexes up to 7 d after weaning.

Acute-Phase Proteins↗
PubMed1998

Reproductive health. New perspectives on men's participation.

New information, new understanding, and new approaches promise to help men become full partners in better reproductive health. Men, as well as women, play key roles in reproductive health, including family planning, but increasing men's participation has been difficult. Adopting new perspectives can help.

Family Planning Services↗
PubMed1996

Possible locus for bipolar disorder near the dopamine transporter on chromosome 5.

The dopamine transporter (DAT) plays a key role in the regulation of dopaminergic neurotransmission by mediating the active reuptake of synaptic dopamine. It is an important candidate gene for bipolar disorder because of data implicating dopamine abnormalities in mania, and because it is the site of action of amphetamine, which has activating and psychotogenic properties. DAT has recently been cloned by its homology to a family of transporters, and mapped to chromosome 5p15.3. We tested DAT for linkage to bipolar disorder in a collection of 21 families from the general North American population (University of California, San Diego/University of British Columbia [UCSD/UBC] families), three Icelandic pedigrees, and Old Order Amish pedigree 110. We examined three markers at DAT, including a 5' TaqI RFLP (HDAT-TaqI), a highly polymorphic variable number of tandem repeats marker (VNTR) (HDAT-VNTR1), and a 3' 40-bp repeat marker (HDAT-PCR1), as well as two nearby microsatellite markers, D5S392 and D5S406. A maximum lod score of 2.38 was obtained at D5S392 in one of the UCSD/UBC families under an autosomal-dominant model. A lod score of 1.09 was also obtained under the same dominant model in the Amish at HDAT-PCR1. In the combined set of families, a maximum lod score of 1.76 was obtained under an autosomal-recessive model at HDAT-TaqI. Positive results were also obtained at several markers, using three nonparametric methods in the UCSD/UBC family set: the affected pedigree member method (P = 0.001), an affected sib pair method (ESPA, P = 0.0008), and the transmission disequilibrium test (P = 0.024). These results suggest the presence of a susceptibility locus for bipolar disorder near the DAT locus on chromosome 5.

Bipolar Disorder↗
PubMed1989

Bright light can delay human temperature rhythm independent of sleep.

New evidence suggest that the phase of human circadian (approximately 24 h) rhythms can be reset by exposures to bright artificial light. This study explored the value of 5 h of bright 3,800-6,000 lx light in resetting human circadian rhythm phases among healthy volunteers. Nine subjects were exposed to 3-5 h bright light for three evenings and to control dim light for an equivalent time, in counterbalanced orders. Electroencephalogram sleep recordings, overnight rectal temperature measurements, and mood scales were obtained. Compared with control dim light, bright light delayed the body temperature rhythm approximately 3 h; however, sleep latency was delayed only 9 min. This suggests that bright light shifted the phase of the human circadian temperature rhythm independent of its effects on sleep phase. Resetting rhythms with bright light may prove useful in treatment of psychiatric disorders.

Adolescent↗
PubMedDate not supplied

Effect of transportation and weaning on humoral immune responses of calves.

Transportation exposes cattle to stress and results in increased morbidity and mortality. An investigation was made of the effects of transport and another important stressor, weaning, on the immune function of calves by determining humoral immune responses to keyhole limpet haemocyanin (KLH). In a 2 x 2 factorial designed experiment, suckled calves were either (1) weaned at housing (day 0) and not transported, (2) weaned at housing and transported, (3) weaned while still at pasture nine to 13 days prior to housing and not transported or (4) weaned at pasture and transported. All calves were immunized with KLH at housing (day 0) and serum samples were collected subsequently to determine class and subclass anti-KLH antibody responses (IgG1, IgG2, IgA and IgM) by direct ELISA. Increased anti-KLH IgG1 and IgG2 concentrations were shown in calves that were weaned prior to housing and transported on day 10 (P < 0.05 and P < 0.01 respectively). Transported calves had increased IgG1 concentrations on day 20 (P < 0.05) compared with calves that were not transported. However, calves weaned at housing and not transported had increased IgA and IgM responses on day 30 compared with the other groups of calves (P < 0.05). This study shows that transportation and weaning affect the humoral immune responses of suckler calves and that the effects persist for several weeks. However, the effects of the treatments were not consistent for all antibody classes measured.

Animals↗