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Biomedical subjects

B A Campbell

Publications and source records attributed to B A Campbell.

At least 19 recordsLinked to original sources
PubMed1992

Developmental constraints on the expression of behavioral and heart-rate orienting responses: II. The role of ambient temperature.

The effect of ambient temperature on the expression of behavioral and heart-rate orienting responses to a novel olfactory stimulus was examined in rats 1-18 days of age. There was no effect of ambient temperature on the behavioral orienting responses at any age. Ambient temperature did influence the expression of the heart-rate orienting response and did so differentially as a function of age. The implications of these findings for developmental models of attention and cognition are discussed.

Animals↗
PubMed1992

Perinatal ovarian cyst: a nonsurgical approach.

A case of an ovarian cyst diagnosed antenatally by ultrasound and showing spontaneous resolution within 5 months after birth is presented. On the basis of this case and others reported in the literature, we recommend expectant follow-up of such lesions with operation recommended only for cysts with solid or complex components or cysts causing symptoms from large size or torsion.

Female↗
PubMed1992

Developmental changes in the duration of attention to unfamiliar stimuli in the rat.

The purpose of the present study was to examine developmental changes in the duration of attention to novel auditory stimuli in rats from infancy to adulthood. In all experiments, the cardiac component of the orienting response was used as the index of attention. In the first experiment 16-, 23-, 30-, and 75-day-old rats were exposed to a novel auditory stimulus for 60 s. Animals of all four ages exhibited a marked decrease in heart rate in response to this stimulus. Although there were no significant effects of age on the magnitude of the cardiac response, there were dramatic developmental differences in the persistence of the response. The 16-day-olds maintained a decrease in heart rate for the entire stimulus period, whereas heart rate returned to baseline in the 75-day-olds after only 40 s. The duration of the cardiac response of the 23- and 30-day-olds was between these extremes. In Experiments 2A and 2B the effect of stimulus complexity on duration of the cardiac response was examined. Increasing stimulus complexity prolonged the deceleratory response in the 30-day-olds (Experiment 2A), and decreasing stimulus complexity decreased the duration of the cardiac response in the 16-day-olds (Experiment 2B). The results of these experiments were discussed in the context of Cohen's and Porges's two-phase theories of attention. The findings demonstrate that the initial attention-getting or reactive phase of attention did not change with age, but that the duration of the attention-holding or sustained phase decreased substantially during development.

Acoustic Stimulation↗
PubMed1992

The penicillins.

The penicillins have played a major role in the treatment of many obstetric and gynecologic infections. The advent of the newer broad-spectrum penicillins has allowed their use as single-agent therapy for certain infections. Although toxicity is extremely low, disadvantages of their use include superinfection and induction of resistance. The cost of therapy is comparable with other antibiotics with similar coverage.

Bacterial Infections↗
PubMed1991

Quantification of cervical change: relationship to preterm delivery in the multifetal gestation.

Prematurity is the major contributor to the very high perinatal morbidity and mortality associated with multifetal gestations. Antepartum cervical evaluation has been suggested as a way to better define the risk of preterm delivery in multifetal gestations. Weekly digital cervical examinations were performed in 86 twin and 7 triplet gestations that were being monitored in a special antepartum clinic. A cervical score was calculated from each examination by subtracting cervical dilatation in centimeters from cervical length in centimeters. Cervical scores decline gradually with advancing gestation and are influenced by parity and subsequent preterm delivery. Intervals until delivery decrease significantly with lower cervical scores. A cervical score less than or equal to 0 on or before 34 weeks' gestation was strongly predictive of preterm delivery (75%). Only 2 of 78 (2.6%) with a score greater than 0 were delivered within 1 week of the examination. Cervical scoring is a simple, quantifiable, reproducible, and safe method of evaluating preterm delivery risk. An understanding of the prognostic significance of specific cervical scores may be of value in determining the need for obstetric intervention.

Adult↗
PubMed1991

Uterine activity after preterm premature rupture of the membranes.

Preterm premature rupture of the membranes complicates few pregnancies but is a major contributor to overall perinatal morbidity and mortality. Although a reduced incidence of preterm premature rupture of fetal membranes has been reported in women who had antepartum uterine activity monitoring, there are few data regarding uterine activity after preterm premature rupture of fetal membranes. Therefore daily uterine activity monitoring was performed in 101 consecutive women with preterm premature rupture of fetal membranes between 26 and 34 weeks' gestation. The mean gestational ages at rupture and delivery were 31.4 +/- 2.3 and 33.7 +/- 4.5 weeks, respectively. A significant increase in contraction frequency was identified within 24 hours of onset of preterm labor (p less than 0.005). A contraction frequency of four or more per hour predicted the onset of labor within 24 hours with a sensitivity of 72%, a specificity of 90%, a positive predictive value of 54%, and a negative predictive value of 95%. These results indicate that most women with preterm premature rupture of fetal membranes exhibit a baseline contraction frequency that is similar to that of women with intact membranes and premature labor. An abrupt increase in contraction frequency is a warning of impending labor.

Adult↗
PubMed1990

Disruption of noradrenergic, but not serotonergic or opiate, functioning blocks both cardiac and behavioral components of the orienting response in preweanling rats.

Previous work in this laboratory established that selective attention, as measured by the behavioral and autonomic expressions of the orienting response (OR), is not disrupted by either dopaminergic or cholinergic receptor blockade. The present experiments extended this pharmacological analysis of the OR. In Experiment 1, preweanling rats were injected with methysergide maleate, a serotonin receptor blocker. Neither the behavioral nor the heart rate (HR) component of the OR was attenuated. In Experiment 2, the opiate receptor blocker naltrexone also failed to inhibit the HR and behavioral expressions of the OR. alpha-1 adrenergic receptor blockade with WB-4101 in Experiment 3 abolished both the HR and behavioral ORs to the pulsating tone. In Experiment 4, clonidine, which inhibits release of norepinephrine by stimulating alpha-2 autoreceptors, attenuated both behavioral and HR ORs to the pulsating tone in a dose-dependent manner. These data, in combination with the prior findings, suggest that norepinephrine is critically involved in the central process underlying the OR in the rat. Dopaminergic, cholinergic, serotonergic, and opiate receptor blockades do not impair selective attention as indexed by HR and behavioral ORs to an auditory stimulus. In contrast, disruption of noradrenergic functioning via either alpha-1 receptor blockade or alpha-2 receptor stimulation disrupts both the HR and behavioral components of the OR. These results indicate that integrity of central noradrenergic functioning is essential for expression of the OR and for stimulus-directed attention.

Animals↗
PubMed1990

Disruption and recovery of the orienting response following shock or context change in preweanling rats.

Previous research has shown that placement of preweanling rats in an unfamiliar environment inhibits both heart rate and behavioral orienting responses to an auditory stimulus, and that the orienting response gradually reappears during the following 15 min. Four experiments designed to evaluate two potential explanations of this effect were conducted. If the arousal induced by an unfamiliar environment disrupts sensory information processing, so should the arousal induced by mild electric shock. In two experiments, the orienting response was inhibited in proportion to number of shocks received and rate of recovery was comparable to that observed in the unfamiliar environment. New environments also contain many unfamiliar stimuli which may overload the rats' limited information processing capacity. In two experiments a change in environmental stimulation was shown to inhibit the orienting response. Recovery of the orienting response followed the same time course as that seen following shock or placement in an unfamiliar environment. Although the results of this study clearly demonstrate environmental inhibition of the orienting response, they provide little support for either the "arousal" or the "information overload" hypotheses of orienting response inhibition. The implications of these data for current theoretical conceptualizations of the orienting response are discussed.

Acoustic Stimulation↗
PubMed1990

Genetic analysis of the enhancer requirements for polyomavirus DNA replication in mice.

In this report, we describe the first systematic analysis of the genetic requirements for polyomavirus (Py) enhancer-activated viral DNA replication during the acute phase of infection in mice. Four mutants were made which substituted XhoI sites for conserved enhancer consensus sequences (adenovirus type 5 E1A, c-fos, simian virus 40, and a glucocorticoidlike consensus sequence). Viral DNA replication in infected mouse organs was measured by DNA blot analysis. Only the loss of the glucocorticoidlike consensus sequence element significantly reduced Py DNA replication in the kidneys, the primary target organ for viral replication. The loss of the c-fos, adenovirus type 5 E1A, or simian virus 40 consensus sequences, however, expanded organ-specific viral DNA replication, relative to wild-type Py, by allowing high-level replication in the pancreas or heart or both. Analysis of Py variants selected for replication in undifferentiated embryonal carcinoma cell lines (PyF441, PyF111) showed that there was little change in levels of viral DNA replication in kidneys and other organs as compared with those in the wild-type virus. If the entire B enhancer is deleted, only low overall levels of viral replication are observed. Wild-type levels of replication in the kidneys can be reconstituted by addition of a single domain from within the A enhancer (nucleotides 5094 to 5132) to the B enhancer deletion virus, suggesting that a single domain from the A enhancer can functionally substitute for the entire B enhancer. This also indicates that the determinants for kidney-specific replication are not found in the B enhancer.

Animals↗
PubMed1990

Objective tocodynamometry identifies labor onset earlier than subjective maternal perception.

The ability of women instructed in self-detection of uterine contractions to identify the abrupt rise in uterine activity known to precede the onset of labor has not been evaluated. This study was designed to assess the temporal relationship between objective uterine activity monitoring, subjective maternal perception of uterine activity above a commonly used threshold value (four or more contractions per hour), and progressive cervical change. Daily tocodynamometry (7-9 AM) was recorded in 79 women with preterm premature rupture of the membranes from admission until the onset of spontaneous labor (5.3 +/- 6.3 days). The subjects were at bed rest, received no tocolytic therapy, and were instructed in the signs of labor and uterine self-palpation. Patients simultaneously provided a subjective assessment of uterine activity (four or more contractions per hour). The majority of uterine activity recordings (78%) revealed fewer than four contractions per hour, and the patients' subjective reports agreed in almost all instances (97.6%). On 91 days, four or more contractions per hour were recorded objectively, but the patients' subjective reports agreed in only 25 instances (27%). On the day of labor onset, significantly more women had an objective assessment (32%) (P less than or equal to .01). Patients subjectively identified labor onset 10.6 +/- 6.7 hours after objective monitoring indicated increased uterine activity, and when subjectively identified, both cervical dilatation (4.9 +/- 2.5 cm) and effacement (85 +/- 30%) were significantly advanced (P less than or equal to .001) compared with the admission examination (1.1 +/- 1.2 cm; 20 +/- 30%).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiotocography↗
PubMed1989

Effect of maternal presence on the cardiac and behavioral responses to shock in rats as a function of age.

In two experiments the effects of the presence of an anesthetized lactating dam on the developing rat's response to a series of mildly painful shocks was examined. Both cardiac and behavioral responses to the shock stimulus were recorded. In the first experiment animals were tested at either 16, 20, or 24 days of age. The presence of the anesthetized dam markedly reduced the behavioral response to shock of the 16-day-old but not the older rats. A similar pattern of results was obtained with the shock-elicited tachycardia. The second experiment replicated these results with the 16-day-old rat and also demonstrated that being shocked in the presence of a lactating dam influences the animal's reaction to a subsequent series of shocks given when it is alone. The results of these two experiments are discussed in terms of other studies that have examined the influence of maternal presence on the developing animal's response to stressful or painful stimuli.

Aging↗
PubMed1989

Role of the central nucleus of the amygdala in olfactory heart rate conditioning.

The role of the central nucleus of the amygdala on olfactory heart rate conditioning in the infant rat was investigated. The conditioned stimulus consisted of a 10-s presentation of grape juice odor that was immediately followed by a 0.5-s, 0.35-mA subcutaneous shock. A sensitization control group was also run. Three days prior to testing, Ss received either bilateral electrolytic lesions of the central nucleus of the amygdala, sham lesions, or were left unperturbed. Results show that damage to the central nucleus of the amygdala severely impaired olfactory heart rate conditioning but that it had no deleterious effect on the heart rate orienting response to that stimulus or on the heart rate unconditioned response to shock. Results are analogous to those in previous research on auditory heart rate conditioning and suggest that the central nucleus of the amygdala may constitute a necessary stage in the transduction of a conditioned stimulus into a cardiac conditioned response regardless of sensory modality.

Amygdala↗
PubMed1988

Ontogeny of conditioned heart rate to an olfactory stimulus.

When heart rate is used as the index of conditioning, rat pups younger than 15 days of age do not display an odor-shock association. This constitutes a marked delay relative to the development of a somatomotor conditioned response. The incapacity to display autonomic learning to an olfactory stimulus prior to day 15 is not due to the inability to perceive and to orient to the olfactory stimuli used, nor to the inability to make unconditioned phasic cardiac changes. Rather, the late development of the heart rate conditioned response may indicate that the central neural mechanisms mediating heart rate conditioning are distinct from, and mature later than those mediating 1) heart rate orienting and 2) somatomotor conditioning. Evidence from studies in adult species is used to support these speculations.

Aging↗
PubMed1988

Unfamiliar environments impair information processing as measured by behavioral and cardiac orienting responses to auditory stimuli in preweanling and adult rats.

Placing animals in an unfamiliar environment triggers at least two major reactions: (1) a heightened state of arousal, fear, or distress and (2) a sharp increase in information processing as the animal attempts to learn about its new environment. These changes could have a profound effect on the way in which the animal reacts to the types of extraneous innocuous stimuli typically used to study learning and memory. For example, an increase in arousal or fear could either (1) make the animal more "attentive" to stimulus change resulting in a larger orienting response, or (2) produce a shift from orienting to defensive responding. Conversely, processing of the new stimuli present in the unfamiliar environment may make the animal less responsive to additional extrinsic stimulation. These possibilities were examined experimentally using both autonomic and behavioral measures of orienting and defensive responses. The results demonstrated that animals fail to exhibit either an orienting response or a defensive response to a novel auditory stimulus when they are first placed in an unfamiliar environment. With continued exposure to the test environment the orienting response appears and then shows a time-dependent increase in magnitude. This pattern of results was obtained in both preweaning and young adult rats. On the basis of additional research and analysis, it was concluded that a limitation in information processing capacity was the primary reason for the failure of the orienting response to occur when an animal is first placed in an unfamiliar test chamber.

Aging↗
PubMed1988

Effect of maternal presence on the fear response to an unfamiliar environment as measured by heart rate in rats as a function of age.

Rats 16 to 60 days of age were placed in an unfamiliar environment either alone or in the presence of an anesthetized lactating dam. Rats of all ages show a dramatic increase in fear, as measured by heart rate (HR), when placed alone in an unfamiliar environment. Adult rats, however, show a rapid decline in heart rate during the course of a 90-min session, whereas 16-day-old rats show no significant decrease in HR during the same period. These results suggest that the adult rats become less fearful of the test environment over time, but that the 16-day-olds maintain a high level of fear throughout the 90-min test period. Twenty-three- and 30-day-old rats show an adultlike pattern of adaptation to the unfamiliar environment, i.e., their heart rates return partially but not completely to baseline levels within the 90-min session. When an anesthetized lactating dam is present in the test environment, a strikingly different pattern of results is obtained. Heart rate in the 16-day-old rat is immediately reduced to near baseline levels whereas in the young adult (60-day-old) rat the presence of the anesthetized dam has no effect on either initial HR or rate of adaptation. Again the 23- and 30-day-old rats showed an intermediate pattern of adaptation. In two follow-up experiments the effects of adding (Expt. 2) or removing (Expt. 3) an anesthetized dam on the 16-day-old rats' response to an unfamiliar environment was examined. Both experiments showed that animals were more fearful when the dam was absent from the environment than when it was present.

Aging↗
PubMed1988

Effect of chronic undernutrition on susceptibility to cold stress in young adult and aged rats.

Chronically undernourished laboratory rodents live as much as 50% longer than matched control animals fed ad libitum. In their natural habitats, however, most mammals, including humans, appear to have shorter life expectancies when chronically undernourished. The present research demonstrated that both brief and chronic undernutrition speeds rate of body temperature drop in rats exposed to cold air. Furthermore, chronic undernutrition also decreased the rate at which body temperature returned to normal after animals had been removed from the cold environment. These results suggest that while chronic undernutrition may slow the rate of physiological aging it also increases the organism's susceptibility to stressor stimuli.

Aging↗