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PubMed1984

Single-layer polypropylene colorectal anastomosis. Experience with 100 cases.

The technique of single-layer continuous polypropylene colorectal anastomosis is described. The authors' experience with their initial 100 cases is analyzed in detail. No clinical leaks or anastomotic strictures were noted in a two-year follow-up period. The technique is safe, easily learned, rapidly performed, and it does not add significantly to the cost of medical care. The authors' total experience with this anastomosis now exceeds 350 cases.

Adolescent↗
PubMed2002

Distribution-dependent saccades in children with strabismus and in normals.

To guide saccades accurately human adult subjects learn rapidly to aim, in advance, for the central position of the distribution of the target positions studied. This causes a bias called range effect, i.e., saccades to the central location are accurate while the less eccentric locations are overshot and the more eccentric locations are undershot. It is believed that this is a cognitive strategy allowing to reduce overall variability. We show here that the same exists for normal children (5-13 years old). Most importantly, from the age of 5 years, children with strabismus use the same cognitive strategy despite the fact that their eyes are misaligned. Importantly, both eyes follow this strategy even though only one eye is fixating the target (the other eye being squinted).

Adolescent↗
PubMed1989

Chronic flupentixol treatment potentiates the reinforcing properties of systemic heroin administration.

The behavioral effects of systemic heroin administration were examined in rats subjected to flupentixol impregnation prior to and during behavioral testing. In the first experiment, the dose of heroin required to produce a place preference was determined in two groups of rats, one of which had received chronic flupentixol decanoate (12 mg/kg, sc, every 10 days for 6 weeks) and the other which had received the palm oil vehicle during the same time period. It was found that whereas 60 micrograms/kg of heroin was required to produce a place preference in control rats, only 7.5 micrograms/kg was sufficient to do so in chronic neuroleptic-treated rats. In a second experiment, the locomotor activating effect of heroin was evaluated in two groups of rats that had been subjected to the same chronic regimen as in Experiment 1. Locomotor activity was enhanced in both groups following 120 micrograms/kg heroin, whereas 30 micrograms/kg was ineffective in either group. Finally, it was found that neuroleptic-treated, but not control, rats rapidly learned to self-administer intravenous infusions of an unusually low dose of heroin (4 micrograms) and to discriminate these infusions from vehicle infusions. Together, these data show that chronic dopamine (DA) receptor blockade produces a marked increase in the sensitivity to the reinforcing and discriminative stimulus properties of systemic heroin administration and that this increase is not attributable to heroin-induced locomotor activation. The results are discussed in terms of the role of DA systems in opiate reinforcement processes.

Animals↗
PubMed1987

Regional autonomy in the peripheral processing of odor signals in newborn rabbits.

In newborn rabbits, small and apparently arbitrary regions of the olfactory bulb and associated epithelium appear capable of a high degree of odor processing. After medial or lateral removal of up to 80% of the olfactory bulbs, including the accessory bulb, newborn pups were still able to respond appropriately to the pheromone-governing suckling behavior (Expt. I), could rapidly learn to associate a novel, artificial odor with suckling (Expt. II), and continued to respond appropriately to artificial odors learned prior to lesioning (Expt. III). These findings suggest that the perception and recognition of such suckling signals does not depend on the integration of information from the entire bulb or epithelium, and question the extent to which patterns of 2-deoxyglucose uptake in the bulb reflect the neural coding for specific odors. However, as the tasks set here only required detection of odor signals and not true odor discrimination, it may still be that the full bulbar pattern of activation is necessary for higher-order processing, such as distinguishing between odors and attributing different meanings to them.

Animals↗
PubMed1991

The discriminative stimulus effects of neuropeptide Y.

Neuropeptide Y (NPY), an endogenous peptide which strongly induces food intake, is demonstrated to have discriminative stimulus properties when administered intracerebroventricularly. Rats rapidly learned to press the appropriate lever during training. NPY discrimination was dose-dependent. NPY's discriminative stimulus properties were compared to those of two doses of Peptide YY (PYY) and 24 and 48 h of food deprivation, conditions which also increase feeding. Both doses of PYY generalized to NPY, supporting previous findings that PYY has effects similar to NPY. Although food deprivation increases feeding in a manner similar to NPY, food deprivation did not result in NPY-appropriate responding.

Animals↗
PubMed1991

Hippocampal mu-receptors mediate opioid reinforcement in the CA3 region.

Dependence on reinforcing chemicals is manifested when drug-seeking and drug-taking behaviors come to dominate the response repertoire. Clinical observations suggest that the craving and compulsive drug-seeking that characterize drug dependence are aroused by memories of the reinforcing drug experience. If so, a brain structure intimately associated with memory--the hippocampus--would be a plausible substrate for drug reinforcement effects. We report here that drug-naive rats rapidly learn to self-administer the opioid peptide dynorphin A in the CA3 region of hippocampus, and that this behavior is blocked by co-administration of the non-selective opiate antagonist naloxone. Subsequent studies demonstrated that coadministration of mu-, but not kappa- or delta-opioid antagonists also blocked self-administration behavior. We conclude that mu-receptors in the CA3 region of hippocampus may be important target sites for opioid dependence.

Animals↗
PubMed1993

[Leu31,Pro34]neuropeptide Y (NPY), but not NPY 20-36, produces discriminative stimulus effects similar to NPY and induces food intake.

Rats were trained to discriminate between an intracerebroventricular injection of 1.15 nmol of Neuropeptide Y (NPY) and a sham injection. Rats rapidly learned to press the appropriate lever during training. NPY's discriminative stimulus effects were compared to those of saline, and 1.15-3.45 nmol [Leu31,Pro34]NPY, a Y1 receptor agonist and NPY 20-36, Y2 receptor agonist. [Leu31,Pro34]NPY resulted in NPY-appropriate responding, whereas saline and NPY 20-36 did not. [Leu31,Pro34]NPY also increased food intake, but NPY 20-36 did not. This suggests that NPY's discriminative stimulus and orexigenic effects involve the Y1, but not the Y2, receptor.

Animals↗
PubMed1991

Establishing mirror-image discriminations with progressively delayed extra-stimulus prompts.

Progressively delayed extra-stimulus prompts were used to help normal preschool children discriminate left-right mirror-image stimuli. Two issues were addressed, the attention guiding properties of the prompts and the necessity for their gradual elimination. The study consisted of four experiments in which one or multiple prompt conditions were used. Each condition involved three prompts: a reference prompt for indicating the S+ and two superimposed prompts, one on the S+, and one on the S-. The prompts required subjects to respond to the orientation of the S+ (Orientation condition) or to the location of the reference prompt (Location condition); or allowed them to respond to the discriminative shapes of the superimposed prompts (Shape condition). The results showed the following. First, most subjects rapidly learned to respond to the Orientation prompts. Second, delayed orientation prompting was always successful regardless of how the prompts were eliminated. Delay training was never successful in either of the other two conditions. Third, the Orientation condition did not reliably produce learning unless the delayed prompting procedure was used.

Attention↗
PubMed1994

Inhibition of anticipatory salivation and craving in response to food stimuli.

Two experiments were done to study inhibition of cue-dependent salivation and craving responses. Experiment 1 suggests that total prevention of tasting during cue exposure inhibits salivation responses to chocolate cues. On the other hand, salivation was triggered by chocolate cues after tasting a very small amount of chocolate, indicating a very robust and rapid learning of conditioned salivation responses. However, prevention of tasting during cue exposure did not affect craving, suggesting that this method cannot decrease craving or that craving is affected at different rate than salivation. Experiment 2 tested the hypothesis that tasting irrelevant food during repeated exposure to chocolate cues would inhibit anticipatory salivation and craving responses to these cues. No support for this hypothesis was observed.

Adolescent↗
PubMed1993

Active avoidance behavior using pontine nucleus stimulation as a conditioned stimulus in the rat.

Five groups of rats were trained in an active avoidance task in a shuttle box with different conditioned stimuli. Animals with either a light-conditioned stimulus or with electrical stimulation of the ventral pontine nucleus as a conditioned stimulus rapidly learned to avoid an aversive event, while those with no conditioned stimulus, with electrical stimulation of the lateral pontine nucleus or the medial lemniscus did not learn to avoid. Therefore, stimulation of a specific subdivision of the pontine nucleus is as effective as a light-conditioned stimulus to learn an active avoidance task.

Animals↗
PubMed1985

A study of intracerebroventricular self-administration of leucine or methionine enkephalin by rats in response to intermittent electric shocks.

Rats were taught to self-administer Leu-E (10, 25 and 100 micrograms/microliters) or Met-E (0.5, 10 and 100 micrograms/microliters) through a cannula implanted in the lateral cerebral ventricle (i.c.v.). Their self-injection behaviour was studied before, during and after nociceptive stimulation. In the course of the control period of the experiment, the rats rapidly learned lever pressing for self-injection of enkephalin but they did not increase their self-administration of Leu-E or Met-E during the nociceptive electrical stimulation period. Also studied were the acute effect of i.c.v. enkephalin and morphine on tail-flick latency (sec) and electrical threshold vocalization (mA). The analgesic effect of Leu-E and Met-E was of short duration (less than 2-6 min). The mean rise (i.e., analgesia) of the tail-flick threshold showed a significant difference after i.c.v. Met-E only. The acute i.c.v. effect of 20 or 30 micrograms of morphine induced a long-lasting analgesia, greater than 40 min. These results show that Leu-E and Met-E are not rewarding during a nociceptive stimulus. This may be due to the short and inconstant analgesic action of i.c.v. enkephalins.

Animals↗
PubMed2006

The representation of information about faces in the temporal and frontal lobes.

Neurophysiological evidence is described showing that some neurons in the macaque inferior temporal visual cortex have responses that are invariant with respect to the position, size and view of faces and objects, and that these neurons show rapid processing and rapid learning. Which face or object is present is encoded using a distributed representation in which each neuron conveys independent information in its firing rate, with little information evident in the relative time of firing of different neurons. This ensemble encoding has the advantages of maximising the information in the representation useful for discrimination between stimuli using a simple weighted sum of the neuronal firing by the receiving neurons, generalisation and graceful degradation. These invariant representations are ideally suited to provide the inputs to brain regions such as the orbitofrontal cortex and amygdala that learn the reinforcement associations of an individual's face, for then the learning, and the appropriate social and emotional responses, generalise to other views of the same face. A theory is described of how such invariant representations may be produced in a hierarchically organised set of visual cortical areas with convergent connectivity. The theory proposes that neurons in these visual areas use a modified Hebb synaptic modification rule with a short-term memory trace to capture whatever can be captured at each stage that is invariant about objects as the objects change in retinal view, position, size and rotation. Another population of neurons in the cortex in the superior temporal sulcus encodes other aspects of faces such as face expression, eye gaze, face view and whether the head is moving. These neurons thus provide important additional inputs to parts of the brain such as the orbitofrontal cortex and amygdala that are involved in social communication and emotional behaviour. Outputs of these systems reach the amygdala, in which face-selective neurons are found, and also the orbitofrontal cortex, in which some neurons are tuned to face identity and others to face expression. In humans, activation of the orbitofrontal cortex is found when a change of face expression acts as a social signal that behaviour should change; and damage to the orbitofrontal cortex can impair face and voice expression identification, and also the reversal of emotional behaviour that normally occurs when reinforcers are reversed.

Animals↗
PubMed2004

Epidemiology of brain tumors in childhood--a review.

Malignant brain tumors are the leading cause of cancer death among children and the second most common type of pediatric cancer. Despite several decades of epidemiologic investigation, the etiology of childhood brain tumors (CBT) is still largely unknown. A few genetic syndromes and ionizing radiation are established risk factors. Many environmental exposures and infectious agents have been suspected of playing a role in the development of CBT. This review, based on a search of the medical literature through August 2003, summarizes the epidemiologic evidence to date. The types of exposures discussed include ionizing radiation, N-nitroso compounds (NOC), pesticides, tobacco smoke, electromagnetic frequencies (EMF), infectious agents, medications, and parental occupational exposures. We have chosen to focus on perinatal exposures and review some of the recent evidence indicating that such exposures may play a significant role in the causation of CBT. The scientific community is rapidly learning more about the molecular mechanisms by which carcinogenesis occurs and how the brain develops. We believe that advances in genetic and molecular biologic technology, including improved histologic subtyping of tumors, will be of huge importance in the future of epidemiologic research and will lead to a more comprehensive understanding of CBT etiology. We discuss some of the early findings using these technologies.

Animals↗
PubMed1997

Nonpenetrating clips for coronary anastomosis.

BACKGROUND: A nonsuture clip technique (nonpenetrating titanium clips applied to everted tissue edges at high compressive forces) was used to perform coronary anastomoses in a clinical setting. METHODS: Clipped coronary anastomoses were performed in 10 patients. The anastomoses incorporated the left internal mammary artery to the left anterior descending artery (n = 1) and the saphenous vein to the right coronary artery (n = 5), the posterior descending artery (n = 2), the diagonal artery (n = 2), and one vein-to-vein proximal anastomosis (n = 1). RESULTS: The mean duration for completion of the anastomoses was 15 minutes (range, 7 to 20 minutes). This time was reduced from 20 minutes at the beginning of the clinical experience to 7 minutes for the last 3 patients. No technical complication was related to clip application and all patients had uneventful outcomes. Three anastomoses studied by coronary angiography were patent without stenosis. CONCLUSION: The clipped anastomotic technique has a rapid learning curve, the same safety as suture methods, and the potential for facilitating endoscopic vascular reconstructions.

Anastomosis, Surgical↗
PubMed1999

Sex with knockout models: behavioral studies of estrogen receptor alpha.

Estrogens are an important class of steroid hormones, having multiple targets, in the body and brain, and exerting ubiquitous effects on behavior. At present, two estrogen receptors (ERalpha and beta) have been cloned and sequenced in mammals. In the brain these receptors are regionally specific, but both have widespread distributions, which are largely non-overlapping. Given the newly emerging complexities of estrogen's mechanisms of action it is important to distinguish which pathways are involved in modifying which behaviors. We use a knockout mouse, lacking functional copies of the estrogen receptor alpha (ERalpha) gene, to study the mechanisms by which estrogens mediate behaviors. There are pronounced ramifications of ERalpha gene disruption on behavior. First, female ERalpha knockout (ERalphaKO) mice do not display normal feminine sexual behavior. Second, treatment of adult mice with androgens promotes masculine sexual behavior in both sexes. However, male-typical sexual behavior is severely compromised in male and female ERalphaKOs. Third, male ERalphaKOs do not exhibit the same social preferences for female mice as do wildtype (WT) littermates. Thus, the ERalpha is essential for normal expression of sexual behaviors. In addition, gonadectomized ERalphaKO and WT mice rapidly learn to escape from the Morris water maze. Exogenous estrogen treatment prevents WT females from learning this task, yet, has no effect in ERalphaKO mice, suggesting that estrogens effects on learning in adult females involves the ERalpha. Based on these data we hypothesize that ERalpha mediates many of the effects of estrogen on sexual behavior, learning, and memory.

Animals↗
PubMed1979

Object sorting by chimpanzees and monkeys.

Chimpanzees and two species of monkey were compared on sorting tasks. When the sets of objects differed in multiple ways, most chimpanzees learnt to sort whereas only a few monkeys performed better than chance (and then inconsistently). When the objects within a set differed in one or two respects, so that sorting by one principle entailed "unsorting" by one or more alternative principles, chimpanzees had greater difficulty. Two young animals did rapidly learn to sort by color and size ("unsorting" by size and shape or by color and shape). They did not sort pictorial material and had difficulty in sorting by shape if "unsorting" by both color and size. The sorting task differentiated between the cognitive capacities of chimpanzees and monkeys whereas other tasks did not.

Animals↗
PubMed2006

The molecular origins of species-specific facial pattern.

The prevailing approach within the field of craniofacial development is focused on finding a balance between tissues (e.g., facial epithelia, neuroectoderm, and neural crest) and molecules (e.g., bone morphogenetic proteins, fibroblast growth factors, Wnts) that play a role in sculpting the face. We are rapidly learning that neither these tissues nor molecular signals are able to act in isolation; in fact, molecular cues are constantly reciprocating signals between the epithelia and the neural crest in order to pattern and mold facial structures. More recently, it has been proposed that this crosstalk is often mediated and organized by discrete organizing centers within the tissues that are able to act as a self-contained unit of developmental potential (e.g., the rhombomere and perhaps the ectomere). Whatever the molecules are and however they are interpreted by these tissues, it appears that there is a remarkably conserved mechanism for setting up the initial organization of the facial prominences between species. Regardless of species, all vertebrates appear to have the same basic bauplan. However, sometime during mid-gestation, the vertebrate face begins to exhibit species-specific variations, in large part due to differences in the rates of growth and differentiation of cells comprising the facial prominences. How do these differences arise? Are they due to late changes in molecular signaling within the facial prominences themselves? Or are these late changes a reflection of earlier, more subtle alterations in boundaries and fields that are established at the earliest stages of head formation? We do not have clear answers to these questions yet, but in this chapter we present new studies that shed light on this age-old question. This chapter aims to present the known signals, both on a molecular and cellular level, responsible for craniofacial development while bringing to light the events that may serve to create difference in facial morphology seen from species to species.

Animals↗
PubMed2000

Laparoscopic cryoablation of renal masses.

Laparoscopic cryoablation seems to be an effective treatment modality for small peripheral renal tumors. The technique is minimally invasive, has a rapid learning curve, results in minimal blood loss and morbidity, and, to date, has demonstrated precise reliable ablation of small renal neoplasms. Long-term follow-up is necessary to confirm the absence of local tumor recurrence or distant or port-site metastases.

Adult↗