Functional analysis of the sensory motor pathway of resistance reflex in crayfish. I. Multisensory coding and motor neuron monosynaptic responses

The in vitro preparation of the fifth thoracic ganglion of the crayfish was used to analyze the connections supporting the monosynaptic reflex responses recorded from the depressor motor neurons (Dep MNs). Dep MNs are directly connected by the release-sensitive afferents from a proprioceptor, the coxo-basipodite chordotonal organ (CBCO), which is released by upward movements of the leg. Sine-wave movements, applied to the CBCO strand from the most released position, allowed us to stimulate the greatest part of release-sensitive CBCO fibers. Systematic intracellular recordings from all Dep MNs performed in high divalent cation saline allowed us to determine the connections between CBCO afferents and their postsynaptic Dep MNs: it highlighted the sequential activation of the different Dep MNs involved in the monosynaptic reflex. The convergence of different sensory afferents onto a given Dep MN, and the divergence of a given sensory afferent onto several Dep MNs illustrates the complexity of the sensory-motor reflex loops involved in the control of locomotion and posture. Electrophysiological experiments and simulations were performed to analyze the mechanisms by which Dep MNs integrate the large amount of sensory input that they receive. Paired intracellular recording experiments demonstrated that postsynaptic response shapes characteristic of both phasic and phaso-tonic afferents could be induced by varying the presynaptic firing frequency, whatever the postsynaptic Dep MN. Compartment model simulations were used to analyze the role of the sensory-motor synapse characteristics in the summation properties of postsynaptic MN. They demonstrated the importance of the postsynaptic compartment geometry, because large postsynaptic compartments allowed to generate greater excitatory postsynaptic potential (EPSP) summations than small ones. The results presented show that velocity information is the most effective to elicit large compound EPSPs in MNs. We therefore suggest that the negative feedback reflex is mainly based on the detection of leg movements.     

Effects of four maintenance programs on the long-term management of obesity.

This study evaluated the effectiveness of four posttreatment programs designed to enhance the long-term maintenance of weight loss. Mildly and moderately obese adults (N?=?123) were randomly assigned to one of the following five conditions: (a) behavior therapy only; (b) behavior therapy plus a posttreatment therapist-contact maintenance program; (c) behavior therapy plus posttreatment therapist contact plus a social influence maintenance program; (d) behavior therapy plus posttreatment therapist contact plus an aerobic exercise maintenance program; or (e) behavior therapy plus posttreatment therapist contact plus both the aerobic exercise and social influence maintenance programs. All posttreatment programs were conducted in 26 biweekly sessions during the year following behavioral treatment for obesity. At an 18-month follow-up evaluation, all four conditions that combined behavior therapy with a posttreatment maintenance program yielded significantly greater long-term weight losses than behavior therapy alone. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alteration in rate modulation of reflexes to lumbar motoneurons after midthoracic spinal cord injury in the rat. I. Contusion injury

This study investigated the regulation of reflex excitability in normal and midthoracic contusion-injured animals. Recent observations revealed that rate depression, a rate-modulatory process that decreases reflex excitability, was significantly decreased following experimental midthoracic contusion injury. The present experiments were performed to extend those studies and to determine if posttetanic potentiation (PTP), a rate-modulatory process that increases reflex excitability, also was altered in lumbar monosynaptic reflexes (MSRs) following midthoracic contusion injury. In normal animals, a mean PTP of 160% of the pretetanus control was observed at 30 sec following tetanus of the tibial MSR. The decay of the PTP in normal animals followed a rapid initial, then a more gradual pattern, before returning to pretetanus values by 5 min posttetanus. Following midthoracic contusion injury, the maximal (unpotentiated) MSRs were significantly increased in amplitude, whereas the percent potentiation of the PTP of the tibial MSRs was significantly decreased. PTP decay in postcontusion animals was significantly more gradual than observed in normal animals and followed a single decay process. Further analysis of rate depression of tibial MSRs in normal animals revealed that the attenuation pattern produced by stimulation within the lower range of test frequencies was different from that produced by stimulation at the higher test frequencies. Following contusion, rate depression of tibial MSRs was significantly reduced at all test frequencies. These physiological changes in the stretch reflex neural pathway are discussed relative to the development of spasticity.     

Role of supraspinal systems in environmentally induced antinociception: Effect of spinalization and decerebration on brief shock-induced and long shock-induced antinociception.

Prior research suggests that afferent nociceptive information can directly activate the opioid and nonopioid brainstem antinociceptive systems. J. W. Grau (see record 1987-30660-001) has hypothesized that direct activation occurs when an organism is exposed to severe aversive stimuli and that forebrain systems mediate the activation of the antinociception systems when mild aversive stimuli are used. The present experiments tested this hypothesis by examining the impact of spinalization and decerebration on the antinociception observed after mild (3 0.75-s 1.0-mA shocks) and severe (3 25-s 1.0-mA shocks) tailshocks. It was found that spinal transection eliminated the antinociception observed after both shock schedules, whereas decerebration blocked mild shock-induced, but not severe shock-induced, antinociception. Surprisingly, decerebration potentiated severe shock-induced antinociception. The opioid antagonist naltrexone had no effect on the antinociception observed after severe shock in sham or decerebrate rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of modeling and reinforcement on adult chronic schizophrenics.

Modified the expressed preferences of 32 male schizophrenics for 8 pairs of popular magazines by 1 of 3 treatments lasting 4 days. Adult male models demonstrated the desired responses in 2 of these treatments. 2 hypotheses generated from studies with children only were tested: (a) model contributes to new learning; and (b) neither the model nor the reinforcement of the model add significantly to motivation, beyond the effect that can be attributed to reinforcement of the S himself. Ss were reinforced socially and monetarily in all treatments: (a) no model, (b) model reinforced, and (c) model not reinforced. A no-treatment control condition was included. Results support the hypotheses. Application of these techniques to the more central informational and motivational deficits of schizophrenics are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of model warmth on imitation learning in adult chronic psychotics.

Tested predictions derived from social learning research with children, employing experimental dyads. In a factorial design, 18 male and 18 female adult chronic psychotic inpatients either (a) interacted with an adult model who was noncontingently warm and rewarding, (b) interacted with a neutral and nonrewarding model, or (c) were not exposed to a model. In a 2nd phase, the model displayed task responses and novel behaviors incidental to the task, and the S's subsequent imitation of the model was recorded. Findings support the hypotheses that adult chronic psychotics can acquire new behaviors through observation of a model without contingent reward to either party, and that a previously positive relationship with a model facilitates such learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of chronic nicotine on brain stimulation reward. I. Effect of daily injections

Transforming growth factor-beta (TGF-beta) is involved in several autoimmune neurological diseases. It is still unclear whether its local action can be pro-inflammatory or anti-inflammatory in the muscle tissue, because of the few reports on this subject. We have previously shown that human myoblasts secrete interleukin-6 (IL-6) when stimulated with inflammatory cytokine such as interleukin-1beta (IL-1beta) or tumor necrosis factor alpha. In the present report, we show that TGF-beta1 can induce IL-6 production; moreover, costimulation or short term pre-incubation with TGF-beta1 increases IL-1beta effect, while a longer incubation inhibits its action.     

有氧运动对治疗慢性下背痛的疗效

目的:探索有氧运动对治疗慢性下背痛疗效的影响.方法:选择社区医疗服务中心40例病史3个月以上的下背痛患者,采用电脑随机方法将受试者分为两组:一组为实验组,进行有氧训练;另一组为对照组,不接受任何训练计划.对照组和实验组分别在干预介入前与介入后进行下背痛失能程度量表和疼痛评分(Visual Analogue Scale,VAS).结果:治疗12周后,发现实验组在治疗后欧式下背痛失能程度显著小于对照组,且VAS评分结果显著优于对照组.结论:有氧运动可以改善慢性下腰痛患者的疼痛程度及改善其失能状况.     

Effects of phenothiazine withdrawal on proverb interpretation by chronic schizophrenics.

Administered 1 of the clinical forms of the Gorham Proverbs Test to 42 chronic schizophrenics while they were receiving antipsychotic medication and 2 forms 4 wks after drug withdrawal. 21 patients were tested first on drugs and then off, and 21 were tested first off drugs, then on. Some patients improved with drug withdrawal and some worsened. Scores of autism in proverb interpretation and ratings of clinical status agreed (p     

Wheel access duration in rats: I. Effects on feeding and running.

The effects of 0-, 2-, and 24-hr wheel access on the pattern of running, feeding, and weight were explored over 24 days in 3 groups of 8 male rats. Both 2 and 24 hr of wheel access suppressed feeding by about 15% for about 8 days before feeding gradually returned to normal. Weight in these 2 groups was similar and was suppressed for the 24 days. Like the pattern seen with drug self-administration (S. H. Ahmed & G. F. Koob, 1998, 1999), running levels stayed low with short, 2-hr daytime wheel access, but with long, 24-hr access, rats' running escalated over days to chronically high levels. These results may have relevance for the understanding of addiction and anorexia nervosa. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of botulinum neurotoxin type A on abducens motoneurons in the cat: ultrastructural and synaptic alterations

The synaptic alterations induced in abducens motoneurons by the injection of 3 ng/kg of botulinum neurotoxin type A into the lateral rectus muscle were studied using ultrastructural and electrophysiological techniques. Motoneurons identified by the retrograde transport of horseradish peroxidase showed a progressive synaptic stripping already noticeable by four days post-injection which increased over the study period. By 35 days post-injection, the normal coverage of motoneurons by synaptic boutons (66.4 +/- 4.0%) significantly decreased to 27.2 +/- 4.0%. Synaptic boutons detached by a widening of the subsynaptic space but remained apposed by synaptic contacts and desmosomes to the motoneuron. Detachment did not affect equally flat and round vesicle-containing boutons. The control motoneuron had almost equal numbers of both types of boutons, but after 35 days post-injection the ratio of round to flat vesicle-containing boutons was 1.20 +/- 0.01. Synaptic boutons impinging on motoneurons showed signs of alterations in membrane turnover, as indicated by an increase in the number of synaptic vesicles and a decrease in the number of coated vesicles and synaptic vesicles near the active zone. Abducens motoneurons had a transient increase in soma size by 15 days that returned to normal at 35 days, but no signs of chromatolysis or organelle degeneration were seen. Accompanying the swelling of motoneurons, a 15-fold increase in the number of spines, very infrequent in controls, was observed. Spines located in the soma and proximal dendritic trunk received synaptic contacts from both flat and round vesicle-containing boutons that could be either partly detached or completely attached to the motoneuron. An increased turnover of the plasmatic membrane of the motoneuron was observed, as indicated by a four-fold increase in the number of somatic coated vesicles. Animals were implanted with bipolar electrodes in the ampulla of both horizontal semicircular canals for evoking contralateral excitatory and ipsilateral inhibitory postsynaptic potentials. Motoneurons were antidromically identified from the lateral rectus muscle. Synaptic potentials of vestibular origin were recorded in abducens motoneurons. In the period between two and six days post-injection, a complete abolition of inhibitory synaptic potentials was observed. By contrast, excitatory synaptic potentials remained, but were reduced by 82%. The imbalance between excitatory and inhibitory inputs to motoneurons induced a progressive increase of firing frequency within a few stimuli applied to the contralateral canal. Between 7 and 15 days post-injection, both excitatory and inhibitory postsynaptic potentials were virtually abolished and remained so up to the longest time checked (105 days). Some motoneurons recorded beyond 60 days post-injection showed signs of recovery of excitatory postsynaptic potentials. During the whole time-span studied, presynaptic wavelets were present, indicating no affecting of the conduction of afferent volleys to the abducens nucleus. Taken together, these data indicate that botulinum neurotoxin at high doses causes profound synaptic alterations in motoneurons responsible for the effects seen in the behavior of motoneurons recorded in alert animals.     

Effects of temperature on ultraviolet-induced erythema of human skin. I. Convective cooling

Convective cooling of human skin to 20 degrees C or less for 1 h immediately after ultraviolet-B irradiation (UV-B, 290-320 nm) results in a significant increase in erythemal threshold when erythema was observed at 4-6 h postirradiation. Cooling the skin immediately before UV-B irradiation showed no consistent influence on the erythema response. In neither case was an effect of cooling on erythemal threshold apparent when erythema was evaluated at 24 h postirradiation. These effects may be due to alterations in the diffusion kinetics of chemical mediators of inflammation, modification of vascular responsiveness, or reflect changes in temperature-dependent cellular repair or expression of UV-induced damage.     

Effects of botulinum neurotoxin type A on abducens motoneurons in the cat: alterations of the discharge pattern

The discharge characteristics that abducens motoneurons exhibit after paralysis of the lateral rectus muscle with botulinum neurotoxin type A were studied in the alert cat. Antidromically identified motoneurons were recorded during both spontaneous and vestibularly induced eye movements. A single injection of 0.3 ng/kg produced a complete paralysis of the lateral rectus muscle lasting for about 12-15 days, whereas after 3 ng/kg the paralysis was still complete at the longest time checked, three months. Motoneurons recorded under the effect of the low dose showed differences in their sensitivities to both eye position and velocity according to the direction of the previous and ongoing movements, respectively. These directional differences could be explained by post-saccadic adaptation of the non-injected eye in the appropriate direction for reducing ocular misalignment. Thus, backward and forward post-saccadic drifts accompanied on- and off-directed saccades, respectively. The magnitude of the drift was similar to the magnitude of changes in eye position sensitivity. The discharge of the high-dose-treated motoneurons could be described in a three-stage sequence. During the initial 10-12 days, motoneuronal discharge resembled the effects of axotomy, particularly in the loss of tonic signals and the presence of exponential-like decay of firing after saccades. In this stage, the conduction velocity of abducens motoneurons was reduced by 21.4%. The second stage was characterized by an overall reduction in firing rate towards a tonic firing at 15-70 spikes/s. Motoneurons remained almost unmodulated for all types of eye movement and thus eye position and velocity sensitivities were significantly reduced. Tonic firing ceased only when the animal became drowsy, but was restored by alerting stimuli. In addition, the inhibition of firing for off-directed saccades was more affected than the burst excitation during on-directed saccades, since in many cells pauses were almost negligible. These alterations could not be explained by adaptational changes in the movement of the non-injected eye. Finally, after 60 days the initial stages of recovery were observed. The present results indicate that the high dose of botulinum neurotoxin produces effects on the motoneuron not attributable to the functional disconnection alone, but to a direct effect of the neurotoxin in the motoneuron and/or its synaptic inputs.     

Effects of chronic unemployment and acute psychological stress on sexual arousal in men.

Ten unemployed (high-chronic-stress) and 9 employed (low-chronic-stress) men were exposed to 2 erotic videotapes (EVs) in the laboratory. Acute stress was induced by telling the Ss that they would have to give a talk on their own sexual behavior and fantasies. Half the Ss were told about the talk before seeing either EV; the other half were told in between the 2 EVs. The unemployed Ss achieved less penile tumescence than the employed Ss when stressed prior to erotic stimulation. Presentation of the stressor between the EVs produced no differences between employed and unemployed Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of hemodilution on splanchnic perfusion and hepatorenal function. I. Splanchnic perfusion

Perfusion of intestinal organs increases in response to acute normovolemic hemodilution (ANH). However, detailed studies on distribution of regional splanchnic organ perfusion during ANH are lacking. We therefore carried out this study to test the hypothesis that ANH does not cause disturbance of physiologic patterns of regional splanchnic organ blood flow. After governmental permission, 22 anesthetized dogs were instrumented to allow invasive hemodynamic measurements and intracardial injection of radioactive microspheres (diameter 15 micro m) for determination of regional organ perfusion. Measurements were made at baseline (hematocrit 37 +/- 3%) and after ANH with 6% hydroxyethyl starch (mol. wt. 200000 / 0.5) to hct 20 +/- 1%. After completion of the protocol, splanchnic organs were removed and dissected into small samples according to anatomical and functional principles. Regional perfusion was determined based on the microsphere content of each sample. Hepatic, intestinal, and pancreatic blood flow increased with ANH. Hepatic arterial blood flow rose by 86%, whereas portal venous perfusion increased by 28%. Small intestine mucosal perfusion was augmented by 68% while the non-mucosal tissue compartment of the gut wall received 32% more blood flow after ANH which is in proportion to the increase in cardiac index after ANH. This redistribution of intestinal flow might be the basis for the preservation of tissue oxygenation during moderate isovolemic anemia.     

Effects of risperidone on polydipsia in chronic schizophrenia patients

A total of 34 patients with advanced ovarian cancer, who relapsed 1-72 months after at least one first-line cisplatin-based chemotherapy protocol, were treated with carboplatin, 350 mg/m2 q 4 weeks, with the adjunct of primary prophylactic granulocyte colony stimulating factor (G-CSF; filgrastim), 300 or 480 microg daily, days 5-9. Over 90% of the anticipated dose of carboplatin could be administered. Partial response, defined as a decline in CA-125 of 50% or more on two consecutive samples, occurred in 42%, while 15% of patients achieved a complete response (no clinical signs of disease with normalization of CA-125). Survival from start of carboplatin treatment was 23 months. Myelosuppression was the most important toxicity with 35% of patients experiencing grade 4 thrombocytopenia of short duration. Grade 4 leucopenia occurred in only one patient. It is concluded that single-agent carboplatin, with the adjunct of prophylactic G-CSF, can be administered with adequate dose intensity, and is an effective and acceptable palliative treatment for patients with relapse after first-line cisplatin-based chemotherapy.