Biomedical subjects

D M Hodgson

Publications and source records attributed to D M Hodgson.

23 records · Page 2Linked to original sources

PubMed1996

Fetal neurobehavioral development.

The ontogeny of fetal autonomic, motoric, state, and interactive functioning was investigated longitudinally in a sample of 31 healthy fetuses from 20 weeks through term. Fetal heart rate and movement data were collected during 50 min of doppler-based fetal monitoring at 6 gestational ages. Measures of fetal heart rate and variability, activity level and vigor, behavioral state, and reactivity were derived from these digitized data. Weighted least squares analyses were conducted to model the developmental patterns and to examine the role of maternal and fetal covariates. With advancing gestation, fetuses displayed slower heart rate, increased heart rate variability, reduced but more vigorous motor behavior, coalescence of heart rate and movement patterns into distinct behavioral states, and increasing cardiac responsivity to stimulation. Male fetuses were more active than female fetuses, and greater maternal stress appraisal was associated with reduced fetal heart variability. An apparent period of neurobehavioral transition exists between 28 and 32 weeks. Fetal research methods are evaluated.

Adult↗

PubMed1996

Fetal antecedents of infant temperament.

This study established the emergence of stable individual differences in neurobehavioral functioning prior to birth and examined their relation to subsequent infant temperament. Fetal heart rate and movement were recorded longitudinally for 31 fetuses at 6 gestational ages beginning at 20 weeks' gestation. Maternally reported temperament data were collected at 3 and 6 months. Moderate stability in all measures except reactivity was apparent at some time before birth. By 36 weeks, fetal neurobehavior accounted for between 22% and 60% of the variance in prediction of temperament scores. In general, more active fetuses were more difficult, unpredictable, unadaptable, and active infants. Higher fetal heart rate was associated with lower emotional tone, activity level, and predictability. We conclude that features of fetal neurobehavior provide the basis for individual differences in reactivity and regulation in infancy.

Adult↗

PubMed1994

The impact of inter-pellet interval and polydipsia on hypoalgesia elicited by non-contingent food delivery.

Exposure to non-contingent food delivery has been shown to elicit an increase in nociceptive thresholds in rats. The conditions which elicit analgesia are similar to those that elicit schedule-induced polydipsia. In both instances animals are food-deprived and receive food on an intermittent schedule. Interpellet interval has been found to be an important predictor of schedule-induced polydipsia. Experiment 1 therefore investigated the effect of varying the interval between pellet deliveries on tail flick latencies in rats. The relationship between nociceptive threshold and inter-pellet interval was found to be bitonic in nature given that animals submitted to fixed time schedules of 30 or 60 s, but not 15 or 120 s, exhibited significant increases in tail flick latencies. Experiment 2 examined the effect of providing animals with water during exposure to non-contingent food delivery. Under these conditions animals exhibited polydipsic behaviour, the development of which attenuated the hypoalgesic response to non-contingent food delivery.

Animals↗

PubMed1991

Control of food delivery in food-deprived rats mediates analgesia.

An experiment was carried out to investigate the effects of control of food delivery, in food-deprived rats, on analgesia. Tail flick latency was used as an index of pain sensitivity and naloxone reversibility of analgesia was used as the criterion for opioid involvement. Food-deprived rats were submitted to one of two schedules of food delivery. The 'contingent' group could control the delivery of food by lever-pressing. The 'non-contingent' group received the same number of food pellets but delivery of food was independent of lever-pressing behaviour. Animals in the 'control' group were placed in the test chamber but did not receive any pellets. Subjects were tested on 6 consecutive days, each test session being of 10 min duration. Half of the animals in each group received an intraperitoneal injection of saline (0.5 ml) prior to each test session, the other half received an intraperitoneal injection of naloxone (5 mg/kg in 0.5 ml saline) prior to each session. Both contingent and non-contingent food delivery resulted in a significant post-test analgesia. The analgesia was noticeably greater when food delivery was non-contingent and this analgesia was reversible by naloxone. The findings suggest that non-contingent food delivery, in food-deprived rats, elicits an opioid analgesia, whilst contingent food delivery elicits a non-opioid analgesia.

Analgesia↗

PubMedDate not supplied

Effect of acute dietary restriction on the colonization of MADB106 tumor cells in the rat.

The effects of acute food restriction (i.e. 24-72 h) on (1) the colonization of MADB106 tumor cells; (2) the response of specific T cell subsets in peripheral blood (i.e. CD4+ and CD8+ cells), and (3) natural killer cell activity (NKCA) in the spleen were studied in the Fischer 344 rat. Previous studies have demonstrated that the spread of this tumor cell is enhanced by exposure to an acute stressor within 24 h of tumor inoculation. Consistent with these reports, 72-hour food restricton after tumor inoculation enhanced colonization of tumor cells to the lungs when assessed 4 weeks after inoculation. Food restriction was found to markedly influence the percentage of T cell subsets (i.e. CD4+ and CD8+ cells) and NKCA in the early (24-72 h) postinoculation stage. At 72 h after inoculation, food restriction was associated with a significant reduction in the percentage of CD4+ cells in tumor- or saline-inoculated animals. The percentage of CD8+ cells was significantly increased at 24 and 72 h after tumor inoculation in ad libitum, but not in food-deprived animals. NKCA at 72 h was significantly reduced in saline-treated food-deprived animals compared to animals fed ad libitum. Given that glucocorticoids are typically increased during acute food deprivation and that glucocorticoids are in some instances associated with depressed NKCA, the present study investigated whether there was a relationship between plasma glucocorticoid levels (i.e. corticosterone) and NKCA; however, no significant relationship was found. In conclusion, the present findings demonstrate that 72-hour food deprivation is associated with enhancement of tumor metastasis. This outcome is mediated, at least in part, by the modulatory effect of the physiological response to acute food restriction upon the distribution of circulating T cells and NKCA in the spleen during the early (24-72 h) postinoculation phase.

Adenocarcinoma↗