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B T Felt

Publications and source records attributed to B T Felt.

16 recordsLinked to original sources
PubMed2006

Alterations in intracerebral hemorrhage-induced brain injury in the iron deficient rat.

BACKGROUND: Iron contributes to brain edema and cellular toxicity after intracerebral hemorrhage (ICH). Knowledge regarding ICH in the context of iron deficiency anemia (IDA), a common nutritional disorder, is limited. OBJECTIVE: To determine the effect of IDA on brain and behavioral outcome after ICH in rats. METHODS: Six-week-old male rats (n = 75) were randomized to non-IDA or IDA groups. After 1 month of iron sufficient or deficient diets, 100 microl autologous blood was infused into the right basal ganglia (BG). Brains were assessed for iron concentration, regional water content, BG transferrin, and transferrin receptor concentrations after ICH. Recovery of upper extremity sensorimotor function was assessed. Brain and behavioral variables were compared by diet group. Significance was set at p < 0.05. RESULTS: Whole brain iron was decreased and water content was increased for IDA rats in injured cortex and BG at day 3 (p < 0.05) compared with non-IDA rats. Transferrin and transferrin receptor content were increased in injured BG for IDA compared to non-IDA in the first week after ICH (p < 0.05). IDA rats had greater left vibrissae-stimulated forelimb-placing deficits and forelimb-use asymmetry than non-IDA after ICH (p < 0.05). CONCLUSIONS: Brain iron status may be an important determinant of injury severity and recovery after ICH.

Anemia, Iron-Deficiency↗
PubMed2001

Behavioral/environmental intervention improves learning after cerebral hypoxia-ischemia in rats.

BACKGROUND AND PURPOSE: In premature infants, many of whom experience ischemic brain insults, the environment of rearing influences cognitive outcome. We developed a model to evaluate the effect of rearing conditions on learning after unilateral cerebral hypoxia-ischemia (HI) in 7-day-old (P7) rats. We hypothesized that neonatal handling would benefit rats recovering from an episode of HI. METHODS: Seventeen litters of P7 Long-Evans rats underwent either HI (right carotid ligation followed by 1.5 hours in 8% O(2)) or control procedures. From P8 to P14, randomized litters were either handled (15 minutes of separation from dam per day) or nonhandled. After P55, learning was tested in the Morris water maze. To evaluate injury severity, hippocampal, cortical, and striatal volumes were measured. RESULTS: In water-maze performance, ANCOVA revealed an interaction between handling and severity of hippocampal damage. Among HI rats, handled rats learned faster when hippocampal damage was moderate (P<0.01, repeated-measures ANOVA), with no benefit when damage was mild or severe. CONCLUSIONS: These observations suggest the beneficial cognitive effect of neonatal handling was limited to animals with moderate damage. Neonatal handling in post-HI rats may be a useful model in which to study mechanisms underlying the benefits of post-HI developmental intervention.

Animals↗
PubMed2000

Behavioral interventions reduce infant distress at immunization.

OBJECTIVE: To assess the effectiveness of simple behavioral interventions at immunization on behavioral and biochemical indicators of distress in infants and parents in a primary care setting. DESIGN: Subjects were enrolled sequentially to control (standard care) and intervention groups. Intervention parents (n=57) were provided information about techniques to help their infants at immunization. Standard care parents (n=45) did not receive this information. Immunizations were videotaped and coded for infant and parent behaviors. Using a visual analog scale, parents rated their infant's and their own comfort at study enrollment, immediately after immunization, and at check-out. Saliva samples collected from infants and parents at study enrollment and at 15, 30, and 60 minutes after immunization were assayed for cortisol concentration by standard radioimmunoassay. Data were analyzed using chi2, analysis of variance, and general linear modeling. Patterns of salivary cortisol change after immunization were analyzed using hierarchical linear modeling. SETTING: A single, urban pediatric practice during 2 summers (1997 and 1998). SUBJECTS: Infants 2 to 24 months of age (n= 102) and their parents. MAIN OUTCOME MEASURES: Duration of infant distress (in seconds); parent use of behavioral intervention; infant and parent salivary cortisol concentrations (in nanomoles per liter). RESULTS: Intervention parents were more likely to use a behavioral technique with their infants before immunization (P<.05). Total infant distress was shorter for intervention infants at immunization (P<.01), and these infants were rated as more comfortable by their parents (P<.001) immediately after immunization. Salivary cortisol levels were lower for intervention infants at 15, 30, and 60 minutes after immunization (P<.05). CONCLUSION: Simple behavioral interventions before immunization are associated with reductions in behavioral and biochemical indicators of infant distress.

Adaptation, Psychological↗
PubMed1996

Brain iron and behavior of rats are not normalized by treatment of iron deficiency anemia during early development.

Previous studies in rats have shown that iron deficiency anemia (IDA) during brain development results in lower brain iron concentration and behavioral deficits that persist despite iron treatment after weaning. The present study used a developmental IDA model to determine whether earlier iron treatment might normalize brain iron concentration and behavior. One and one-half week periods of IDA were instituted during early or late gestation or lactation by providing low iron diet to adolescent rat dams and oral iron treatment at the end of the anemia period. The iron deficiency anemia of dams during gestation and lactation resulted in significantly lower pup brain iron concentration at 3 mo of age (15-33% lower than control), despite iron treatment of dams as early as mid-gestation. Dam IDA during lactation lowered pup brain iron concentration significantly more than IDA during gestation (21% lower). All IDA groups had significantly poorer performance and lower activity compared with controls on a screen of home orientation at 8 d of age. Activity on this test was significantly less than controls at 12 d of age. Homing ability on d 12 and 16 and activity on d 16 did not differ from controls. Groups that were anemic around delivery had significant behavioral differences at 3 mo which included less defecation in the open field and greater swim distance in the Morris maze. These results raise the concern that iron sufficiency throughout the course of rain development is crucial to the achievement of normal brain iron concentration and behavior in rats.

Administration, Oral↗
PubMed1995

Serum prolactin levels and behavior in infants.

This study examined the relationship between serum prolactin levels and behavior in infants and toddlers who experienced two potentially stressful experiences (developmental testing and venipuncture). Serum prolactin levels showed considerable consistency over a 3-month period (r = 0.64 between study entry and three months, p < 0.001, n = 50). There was also stability in having either a normal or a high value (> or = 25 ng/ml). Among children who had a normal value on initial testing, 97% also has a normal value after 3 months; 55% of those with initial high values continued to have high values (chi 2 = 19.26, p < 0.001). Children with high serum prolactin levels were more likely to be rated as unusually hesitant and unhappy during developmental testing. Overall, 53% of the children with serum prolactin levels > or = 25 ng/ml were considered abnormal in affect, compared to 20% of those with lower serum prolactin values (total n = 138, chi 2 = 13.56, p < 0.001). These results suggest that, even in early life, serum prolactin levels may reflect characteristic individual behavioral and neuroendocrine responses to stress.

Female↗
PubMed1982

Development and use of a nonrestraining waveguide chamber for rapid microwave radiation killing of the mouse and neonate rat.

The use of microwave energy for rapid killing of small rodents such as the mouse or rat has become a standard pharmacologic technique since approximately 1975. This method allows investigation of rapidly modulated neurochemical indices, neuromodulatory substances, and some neurotransmitters to be determined at basal concentrations in brain regions and microregions. Previously described devices for use with microwave generators have relied on total body restraining holders in order to properly position rodents and neonates within a closed waveguide during microwave energy exposures. The present information describes two alternate chamber designs which do not require restraint of the rodent. A positioning device is described which must be used with the waveguide chambers. The animal chambers are designed to be used with 2450 MHz energy.

Adenosine Triphosphate↗
PubMed1981

Effect of diesel particulate exposure on adenylate and guanylate cyclase of rat and guinea pig liver and lung.

An examination of the effects of 250 or 1500 micrograms m-3 concentrations of diesel particulate from diesel exhaust on the activity of adenylate or guanylate cyclase was undertaken using liver and lung tissue of rats and guinea pigs. These membrane and cytosolic enzymes were selected to screen for functional or regulatory alterations in these tissues. The studies for adenylate cyclase used the microsomal membrane fraction of each tissue; for guanylate cyclase, the microsomal membrane and supernate fractions were used. Basal and fluoride-stimulated adenylate cyclase activity were measured. Basal and sodium azide-stimulated guanylate cyclase activity were also determined. The basal activity of rat liver adenylate cyclase is generally unchanged throughout 52 weeks of diesel exposure. Stimulated adenylate cyclase shows an age-related decrease for all animal treatments throughout the study. Changes in enzyme activity occurred at 12 weeks and 52 weeks after 1500 micrograms m-3 exposure. Soluble stimulated guinea pig lung guanylate cyclase was first increased (6 weeks) and then decreased (24 weeks) by diesel exposure. At 52 weeks, there was no change. The data suggest the following trends: (1) an increased basal adenylate cyclase in the rat lung; (2) an age-related decrease in adenylate cyclase activity in rat liver, and (3) a biphasic exposure-related response of soluble guanylate cyclase for the guinea pig lung during the first 24 weeks, but no change at 52 weeks. In general, however, these studies suggest that diesel exposure does not substantially alter either of these intracellular regulating enzymes.

Adenylyl Cyclases↗
PubMed1981

Cyclic AMP in female mouse brain is altered by the adrenocorticotropic hormone(4-9) analogue organon 2766.

Cyclic AMP content was determined in 12 brain regions of young adult female mice at 30 min and at 24 h following an intraperitoneal injection of the tri-substituted adrenocorticotropic hormone(4-9) [ACTH(4-9)] analogue Organon 2766 [ORG 2766]. Animals were killed by focused 3.5 kW microwave radiation applied for 350 ms. Unlike previously reported responses in male mice, at 30 min post-injection there were no detectable differences in cyclic AMP content between the placebo and ORG 2766-treated animals. By contrast, 24 h after injection, the content of cyclic AMP was changed significantly in 8 of the 12 brain regions examined: medulla-pons, septal area, thalamus, hypothalamus, hippocampus, olfactory bulb, and parietal and occipital cortices. In most of the regions examined, differences consisted of 50% or greater reductions of tissue cyclic AMP content. The changes were unrelated to the estrus cycle of these animals.

Adrenocorticotropic Hormone↗
PubMed1979

Cyclic nucleotides in the rat neostriatum: push-pull perfusion studies.

A push-pull perfusion technique was employed for in vivo study of adenosine 3',5'-monophosphate (cAMP) and guanosine 3',5'-monophosphate (cGMP) in the rat caudate nucleus. Addition of dopamine to the perfusion fluid elicited dose-dependent increases of both cAMP and cGMP perfusate concentrations. In separate experiments, it was found that pretreatment of animals with the dopamine antagonist, pimozide, significantly depressed both nucleotide responses to dopamine perfusion over the dose range studied. Mechanistic interpretations of the observations are considered. The push-pull perfusion technique appears to provide an extremely useful means of examining extracellular cyclic nucleotide levels in a discrete brain region, in vivo, under dynamic conditions.

Animals↗
PubMed1979

Cerebral blood flow after treatment with ORG-2766, a potent analog of ACTH 4--9.

Regional cerebral blood flows (rCBF) were measured in conscious, male rats at 10, 30, 60 min and 24 hr after intravenous administration of a potent, behaviorally active analog of ACTH/MSH 4--9 (ORG-2766). Flows in the basal ganglia, hippocampus, septal area and frontal cortex were depressed significantly throughout the 60 min postinjection period. HYpothalamic and parietal flows were depressed at 10 and 30 min, but recovered by 60 min, whereas flow to the cerebellum was depressed between 30 and 60 min postinjection. The least changed and therefore relatively better perfused area throughout the first 60 min period was the occipital cortex. By contrast, at 24 hr, when perfusion of all brain regions had returned to near control levels, flow to the occipital cortex was elevated. During the first hour after treatment with either ORG-2766 or alphaMSH the patterns of regional circulation in the brain were qualitatively the same. The data suggest that ORG-2766 and, probably, alpha MSH trigger serially linked neurophysiologic changes in the brain lasting at least 24 hr, which organize the behavioral actions of this class of peptides on memory and attentional processes.

Adrenocorticotropic Hormone↗
PubMed1976

Ultrastructure of the blowfly chemoreceptor sensillum (Phormia regina).

The ultrastructure of a well studied insect chemosensory unit is presented in this report. Two separate lumina are present in this chemosensory unit, the trichogen and sensillar lumina. The fluid within the trichogen lumen exclusively bathes the dendritic terminals, and may be involved with the reception and/or modulation of environmental stimuli. Cytoplasmic extensions of the trichogen cell which line the trichogen lumen may be involved in the production of the cuticular sheath. The sensillar lumen is bordered by the tormogen and a sleeve cell, and is continuous with the unoccupied channel of the setal shaft. Functions for the various cellular components of the blowfly chemoreceptor sensillum are offered.

Animals↗
PubMedDate not supplied

Regulation of hippocampal corticosterone receptors by a vasopressin analogue.

Vasopressin can alter hippocampal corticosterone receptor number, as a congenital absence of a peptide in the Brattleboro rat results in decreased concentrations of the receptor; this deficit can be reversed with des-glycinimide arginine vasopressin (dGVP), a centrally-acting VP analogue. We examined whether vasopressin might regulate less dramatic fluctuations of hippocampal corticosterone receptor number in the normal rat. Administration of dGVP failed to alter the rate of or extent of down- or up-regulation of hippocampal corticosterone receptors by circulating corticosterone, suggesting that alteration of neural VP content is not a mediating step in such regulation.

Adrenal Glands↗