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At least 487 records · Page 27Linked to original sources
PubMed2000

Conditionally immortal neuroepithelial stem cell grafts restore spatial learning in rats with lesions at the source of cholinergic forebrain projections cholinergic forebrain projections Conditionally immortal neuroepithelial stem cell grafts restore spatial leaming in rats with lesions at the source of cholinergic forebrain projections.

Purpose: Loss of cholinergic projections from the basal forebrain (BF) to the cortex and from the medial septal area (MSA) to tbe hippocampus is a reliable correlate of cognitive deficits in aging and Alzheimer's disease (AD). We assessed the capacity of grafts of the conditionally immortal MHP36 clonal stem cell line to improve spatial learning in rats showing profound deficits after lesions to these projections. Methods: Rats were lesioned by infusions of S-AMPA unilaterally into BF or bilaterally into both BF and MSA. MHP36 cells were implanted ipsilaterally in cortex or basal forebrain two weeks after unilateral BF lesions, and in cortex and hippocampus bilaterally six months after bilateral BF-MSA lesions. Intact and lesion-only controls received vehicle. Six weeks later rats were assessed in spatial learning and memory tasks in the water maze, and then perfused for identification of grafted cells by beta-galactosidase immunohistocheniistry. Results: Lesioned rats with MHP36 grafts, whether implanted two weeks or six months after lesioning, learned to find a submerged platform in the water maze as rapidly as intact controls, and showed a strong preference for the platform quadrant on probe trials, whereas lesioned controls were impaired in all measures. Grafted cells of both neuronal and glial morphologies, migrated away from cortical implantation sites in BF Lesioned rats to the striatum, thalamus and basal forebrain lesion area. Cells implanted in basal forebrain showed a similar distribution. In rats with bilateral BF-MSA lesions, grafts implanted in the hippocampus migrated widely through all layers but cortical grafts largely escaped up the needle tract into the meninges. Conclusions: Although MHP36 grafts were functionally effective in both lesion models, the site and age of lesions and site of implantation influenced the pattern of engraftment. This flexibility encourages the development of conditionally immortal human stem cell lines with similar capacities for functional repair of variable neuronal degeneration in AD or aging.

Journal Article↗
PubMed2001

Strength and conditioning practices of National Football League strength and conditioning coaches.

This article describes the results of a survey of the practices of National Football League strength and conditioning (NFL S&C) coaches. The response rate was 87% (26 of 30). This survey examines survey participant (a) background information, (b) physical testing, (c) flexibility development, (d) speed development, (e) plyometrics, (f) strength/power development, (g) unique aspects, and (h) comments. Results reveal that 18 of 26 (69%) NFL S&C coaches follow a periodization model (PM). Of these coaches, 14 of 16 (88%) who responded to the question reported their athletes used Olympic-style lifts, and 17 of 18 coaches (94%) employed plyometric exercises. Coaches who reported following a PM tested an average of 9.8 variables of fitness, which is an average of 3.55 times per year. Seven of 26 (27%) NFL S&C coaches did not follow a PM (NPM). Five of 7 (71%) of these coaches reported following "high-intensity training" (HIT) principles. None of these coaches reported using Olympic-style lifts. Two of 7 (29%) reported using plyometrics. NFL S&C coaches who follow an NPM reported testing an average of 2.12 variables of fitness, which is an average of 2 times per year. A variety of other strength and conditioning practices were examined.

Adaptation, Physiological↗
PubMedDate not supplied

[Water conditioning in extreme conditions].

Comparative analysis of different water conditioning technologies, i.e. supplementing desalted water with certain physiologically important minerals, has been especially concerned with determination of those methods and systems that will fit best the requirements to water processing and mineralization in pressurized habitable modules, spacecraft compartments specifically. It has been concluded that potable water mineralization units designed for these conditions should incorporate filters made of artificial granular materials and take advantage of the osmotic water mineralization technology.

Drinking↗
PubMed1990

[Equipment for respiratory gas conditioning under hygienic conditions].

The significance of respiratory gas conditioning systems as sources of germ colonization and infection of the respiratory tract results from the principle of operation and the temperature. Six respiratory air humidifiers were tested for their hygienic risk in experiments with test germs. Contrary to several reports, some humidifiers were shown to accumulate microorganisms, whereas others do not promote germ population in the respiratory tract even though the water of the humidifier is heavily contaminated. It could be confirmed that basic differences exist between "blow over" and "blow through" humidifiers in the accumulation of microorganisms in respiratory air. Moreover, our investigations revealed that even "blow over" humidifiers should not be considered completely harmless. The "blow over" apparatuses Hydrotrop 200, Aquapor and VH 620 (infant) did not cause any germ propagation in the resuscitation tubes, whereas in the "blow through" apparatuses Bennett Cascade and VH 620 (adult) germ propagation is quite considerable. The mortality kinetics of the germs differ depending on the temperature and the type of apparatus used and should be taken into account when it comes to choosing or developing respiratory gas conditioning devices. Constant heating of the water in the humidifier to a minimum of 50 degrees C provokes a bactericide behaviour of the problem germs. Therefore, it is quite justifiable to do without expensive internationally recommended measures if the humidifier is well chosen. The requirement to replace the humidifier every 24 hours in long-term artificial respiration need not be observed for devices classified as harmless if aseptic handling is guaranteed, i.e. if manual germ transmission by the staff is avoided.

Cross Infection↗
PubMed1989

[Response of human lymphocytes to phytohemagglutinin (PHA) as measured by fluorescence polarization technique--differences between malignant conditions and benign or healthy conditions].

Percoll gradient (density: 1.081 g/cm3) centrifugation of peripheral venous blood yielded two layers of mononuclear cells. Preliminary study using lower lymphocyte layer revealed that there were significant differences in lymphocyte fluorescence polarization changes after PHA stimulation between malignant conditions and benign or healthy conditions, while such differences were not apparent by use of upper lymphocyte layer. According to these preliminary results, we studied fluorescence polarization changes after PHA stimulation in lower lymphocyte layer obtained from 242 individuals, including 49 apparently healthy women, 93 patients with benign gynecological tumor, 17 patients with severe dysplasia of the uterine cervix and 83 patients with malignant gynecological tumor. Stimulation index (R) was defined as the ratio between the degree of polarization before PHA stimulation (P CONTROL) and the degree of polarization after PHA stimulation (PPHA): R = PPHA/PCONTROL. R values of less than unity (R less than 1) indicate stimulation with PHA, and R values of greater than unity (R greater than or equal to 1), non-stimulation with PHA, respectively. R values of less than unity (R less than 1) was found in 118 of 142 (83.1%) healthy women or patients with benign tumor, 5 of 17 (29.4%) patients with cervical dysplasia, and 13 of 83 (15.7%) patients with malignant tumor, respectively. Preoperative R values of greater than unity decreased to R values of less than unity in 17 of 20 (85.0%) patients who received complete resection of the malignant lesion, while decline of R values was noted only in 8 of 22 (36.4%) patients who received incomplete resection of the lesion and/or chemotherapy or radiation. Present findings indicate that fluorescence polarization changes after PHA stimulation in lymphocytes isolated by Percoll gradient facilitate feasible detection of various malignancies.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytoplasm↗
PubMed1980

[Control of puerperium in swine under conditions of extremely shortened nursing method. 1. Results of histological studies in postpartum involution and regeneration of the uterus under conditions of extremely shortened nursing period and medicamentous control of puerperium].

Uterus tissue samples were taken from 31 sows which had been under regimes of extremely shortened nursing periods and differentiated medication to control their puerperium. The samples were taken following laparotomy during the first postpartum oestrus as well as in subsequent phases of the cycle and histologically tested for puerperal involution and regeneration. The endometrium and myometrium of sows in oestrus were found to be in a condition which widely corresponded to normal oestrus condition of the uterus wall, when their piglets had been weaned in the third postpartum week. However, untreated sows in oestrus, whose piglets had been weaned extremely soon, that is in the second postpartum week, displayed numerous signs of inadequate postpartum involution and regeneration. Oxytocin was found to work well in speeding up regeneration of both the endometrium and myometrium. Intramuscular injection of twice nine International Units per die, from the first through ninth days postpartum, helped to complete largely all regeneration processes up to the first oestrus, when piglets had been weaned in the second postpartum week. Oral antibiotic medication (chlortetracycline) and parenteral application of vitamins failed to produce any substantive and histologically recordable effect on puerperal involution processes.

Animals↗
PubMed1993

[Sexual behavior of muscovy ducks under conditions of intensive husbandry of adult animals: dependence on the time of day, husbandry conditions, body mass and health status].

Sexual behaviour of muscovy ducks kept under intensive husbandry conditions is described comprehensively. To characterize the sexual activity qualitatively four different categories were used. It could be demonstrated a typical diurnal rhythm of mating activity with a maximum in the afternoon. The mating activity was diminished also at the end of the laying period. Body mass as well as state of health have an influence on quality and quantity of mating activity. Body weight, mating activity and size of foot pads are correlated with each other; the higher the body weight the higher the size of foot pads and the lower the mating activity. Besides of this, the mating activity is influenced by keeping conditions and genetic factors.

Animal Husbandry↗
PubMedDate not supplied

Simulation of the influence of different factors on the motor nerve condition velocity measurement. Part 1: Normal conditions.

The result of a motor nerve conduction velocity measurement is dependent of a row of factors which will influence the measurement. These factors have been tested extensively in healthy volunteers. However, under pathological conditions it is not known to what degree the reported velocities are influenced by biological and technical factors. In an attempt to broaden our knowledge on the matter, a model was made to test different factors under varying conditions. Part I describes the model and reports results from calculations on simulated normal nerves. The results are in concert with results from healthy volunteers. Part II reports on results in pathological conducting nerves. The effect of the different factors affecting the nerve conduction velocities are shown. A simulation of doing a measurement twice and reporting the average showed a marked decrease of the variability in the reported nerve conduction velocity. This was more effective than eliminating any of the other factors influencing the measured conduction velocity.

Computer Simulation↗
PubMed1992

Possible conditioned stimulus pathway for classical eyelid conditioning in rabbits. I. Anatomical evidence for direct projections from the pontine nuclei to the cerebellar interpositus nucleus.

Wheat germ agglutinin and cholera toxin-conjugated horseradish peroxidase (HRP) were used to retrogradely and anterogradely trace connectivity between the lateral regions of the pontine nuclei and the anterior interpositus nucleus of the cerebellum in rabbits. Projections from the pontine nuclei were found to terminate in the anterior interpositus nucleus and the interpositus was found to send projections to the pontine nuclei. Projections from the nucleus reticularis tegmenti pontis, dorsal accessory inferior olive, and Larsell's lobule HVI of the cerebellum were also found to terminate in the interpositus nucleus and projections from the interpositus nucleus to the inferior olivary complex were observed. The projections from brain stem regions to the interpositus nucleus are discussed as possible pathways that are involved in classical eyelid conditioning.

Animals↗
PubMedDate not supplied

Locus of semantic generalization of the galvanic skin response and possible inhibitory influence of conditional stimuli upon unconditional response following conditioning with innocuous and noxious unconditional stimuli.

Two different problems were investigated using the GSR index of the orienting reflex (OR): 1) the locus of semantic generalization; and 2) a possible inhibitory influence of the CS upon the UCR. Two experiments were conducted. One experiment employed an innocuous USC, and a second similar experiment used a loud noise as the UCS. Unidirectional word associates were employed in the test of the direction of semantic generalization. Constant and varying CS words were used to test the possible inhibitory influence of the CS upon the UCR. Evidence was obtained of semantic generalization occurring in the training and in the test situation. There was no evidence of the CS developing inhibition over the UCR. Theoretical interpretation of both phenomena were considered. The need for developing theories of conditioning of the OR in humans was emphasized in contrast to current efforts to apply inappropriate cognitive animals learning theories which fail to consider biologic constraints.

Adult↗
PubMed1990

Animal models of anxiety based on classical conditioning: the conditioned emotional response (CER) and the fear-potentiated startle effect.

Stimuli consistently paired with shock become capable of suppressing ongoing operant or consummatory behavior (the conditioned emotional response--CER) or elevating the amplitude of the startle reflex (fear-potentiated startle). These changes are used to infer a central state of fear which involves the central nucleus of the amygdala and its efferent projections to the brainstem. The present paper reviews how psychoactive drugs affect these measures. Both the CER and fear-potentiated startle are reduced by benzodiazepines, barbiturates and opiates. Advantages and disadvantages of these animal tests of anxiety are discussed.

Animals↗
PubMed2004

Serial order of conditional stimuli as a discriminative cue for Pavlovian conditioning.

The serial order in which events occur can be a signal for different outcomes and therefore might be a determinant of how an animal should respond. In this report, we propose a novel design for studying serial order learning in Pavlovian conditioning. In both Experiments 1a and 1b, hungry rats were trained with successively presented pairs of auditory and visual stimuli (e.g., A --> B) using four different stimuli (A-D). Four orders were paired with food (A --> B, B --> C, C --> D, D --> A) while the reversals were extinguished (B --> A, C --> B, D --> C, A --> D). An analysis of responding from the second element of each pair showed that the rats discriminated trial types that preceded food from those that did not. A replication of the effect using a completely counterbalanced design is described in Experiment 1b. These results suggest that rats can use the serial or temporal order of two sequentially presented non-overlapping elements as the basis for discrimination. Two associative accounts are suggested as possible mechanisms for solving the discrimination.

Animals↗
PubMed1994

Acquisition of conditional discriminations in hippocampal lesioned and decorticated rats: evidence for learning that is separate from both simple classical conditioning and configural learning.

This study examined whether hippocampal or neocortical lesions would impair acquisition of a discrimination task using taste aversions. Rats were injected with a drug 15 min before a flavored solution-lithium chloride pairing. On alternate days, vehicle injections preceded and followed access to the same flavored solution. Rats learned to consume significantly more of the flavored solution after vehicle injections than after drug injections. Rats with hippocampal lesions or neonatal decortication performed as well as controls. Rats with hippocampal lesions also learned a similar task in which visual and textural cues predicted whether access to a flavored solution would be followed by an injection of lithium chloride or vehicle. However, these hippocampal lesions did impair performance in the Morris water task. Occasion setting may involve a type of learning dissociated from both simple classical conditioning and configural learning.

Animals↗
PubMed2004

Conditions favoring superconditioning of irrelevant conditioned stimuli.

Three appetitive conditioning experiments with rats found partial learning of complex XA+, XB+, XAB- (+ stands for reinforced; - stands for unreinforced) negative patterning discriminations with intermixed A+ and B+ trials (Experiment 1). AB+ trials (Experiment 2), and A+, B+, and AB+ trials (Experiment 3). In all experiments, differential responding emerged more slowly during the learning of the negative patterning discriminations than during learning of the XA+, XB+, XC- control discriminations. Additionally, the negative patterning groups responded more to X than to a separately reinforced Y on unreinforced test trials: thus, X derived superexcitatory properties. This pattern was reversed in the control groups. Results are consistent with theories that allow for different activation patterns when elements are combined.

Animals↗
PubMedDate not supplied

Lidocaine interrupts the conditioned natural killer cell response by interfering with the conditioned stimulus.

In the present study, lidocaine, a local anesthetic that inhibits the initiation or conduction of nerve impulses, was used to differentiate between the memory for the conditioned stimulus (CS) and the memory for the CS and unconditioned stimulus (US) association. Lidocaine was used to block memory formation. It was administered into the cisterna magna to localize the inhibition to the central nervous system (CNS) where circuits for the CS and US exist. The results show that lidocaine specifically blocks the ability of the CS to stimulate the circuits responsible for storing the CS/US association, but it does not interfere with the inherent ability of the US to signal the CNS and trigger a peripheral response. The observation that the CS circuit can be interrupted independently of the US circuit suggests that these signals come together to form a new circuit for the memory of the association. The association memory forms later and is independent of the memory for the CS.

Animals↗
PubMed2006

Experimental control of nodality via equal presentations of conditional discriminations in different equivalence protocols under speed and no-speed conditions.

A within-participant comparison of simple-to-complex, complex-to-simple, and simultaneous protocols was conducted establishing different sets of three 7-member equivalence classes for 4 undergraduate students. The protocols were implemented under either accuracy-only or accuracy-plus-speed conditions while keeping number of presentations of training and testing trials equal. The results partially support previous reports of differential effects on acquisition, with participants completing more blocks in training under the simultaneous than the complex-to-simple and the simple-to-complex protocols. Across the protocols, however, the number of trials completed to criterion did not vary systematically. More important, response speed and accuracy did not decrease as a function of nodal number, with or without the speed contingency, or under any protocol. The latter results challenge the generality of previous reports of the nodality effect and the notion of "relatedness" of equivalence-class members, and support a reinforcement-contingency, instead of a structural, perspective on equivalence-class formation.

Adult↗
PubMedDate not supplied

[Elaboration of conditioned reflexes in dogs grown under conditions of partial intraspecies isolation].

New data are presented on the influence of relationships with representatives of the same species at early stages of ontogenesis on the higher nervous activity of adult dogs. It has been found that dogs raised up to one year with their coevals differ considerably less from the control dogs by the speed of elaboration and stability of complex conditioned reflexes than those raised in complete isolation beginning with the age of three months.

Animals↗
PubMed1976

[Conditioning of emotional behavior caused by hypothalamic stimulation (4). Effects of drugs on conditioned avoidance and escape behavior].

In the present study, effects of psychotropic drugs were analyzed by observing avoidance and escape behavior or rabbits under hypothalamic electrical stimulation. In avoidance behavior, chlorpromazine (CPZ) and diazepam (DZP) depressed avoidance response and extended avoidance response latency and head movement latency. Autonomic behavior such as opening of palpebral fissure and pupil size were also delayed. The locus of movement and count of head movement were depressed by the administration of each drug. On the other hand, unlike CPZ, DZP extended escape response latency. On escape behavior, effects of CPZ and DZP were apparently different. Unlike CPZ, DZP induced avoidance behavior and increased locus of movement. With methamphetamine, no avoidance behavior was observed, but under conditional stimulation, the behavior and the escape response latency were decreased. Chlordiazepoxide induced avoidance behavior.

Animals↗