A spectroscopic analysis code for spatially resolved x-ray absorption data from the COAX platform.

Sophisticated tools such as computer vision techniques in combination with 1D lineout type analyses have been used in automating the analysis of spectral data for high energy density (HED) plasmas. Standardized automation can solve the problems posed by the complexity of HED spectra and the quantity of data. We present a spectroscopic code written for automated and streamlined analysis of spatially resolved x-ray absorption data from the COAX platform on Omega-60. COAX uses radiographs and spectroscopic diagnostics to provide shock position and density information. We also obtain the more novel spectral-derived spatial profile of the supersonic radiation flow into a low-density foam. Considerable effort has been spent modernizing our previous spectroscopic analysis method, including the development of new tools characterized by a faster runtime and minimal user input to reduce bias and a testing suite for verifying the accuracy of the various functions within the code. The new code analyzes our spectroscopic images in 1-2 min, with added uncertainty and confidence.

Ventral posterior thalamic neurons differentially responsive to noxious stimulation of the awake monkey.

Of 76 cutaneously activated neurons recorded from the ventral posterior thalamus of awake, behaving monkeys, nine were weakly excited by innocuous skin stimulation and responded maximally only when noxious mechanical cutaneous stimuli were delivered within small, contralateral receptive fields. These results show that neurons capable of encoding the spatial and temporal features of noxious stimuli are located in the ventral posterior thalamus of the awake primate.

Ligand dynamics and protonation preferences of Rh and Ir complexes bearing an almost, but not quite, pendent base.

Pendent nucleophiles are essential partners in the cleavage and formation of bonds with hydrogen (e.g. protonation/deprotonation), but binding of the pendent group to the metal and the potential trapping of complexes in inactive states are a significant problem. The dipyridylmethane-based ligand framework bis(2-pyridyl)-N-pyrrolidinomethane (R,pyrCPy2), bearing a hemilabile pyrrolidine moiety, has been synthesized and complexes of the type [(R,pyrCPy2)M(COD)]X (COD = 1,5-cyclooctadiene) were prepared. The solution-phase ligand dynamics and relative protonation preferences were investigated via1H NMR spectroscopy; although favorable, pendent amine binding does not kinetically inhibit pendent base protonation. Protonation at the metal (with concomitant pyrrolidine binding) has been found to be favorable for Ir, whereas N-protonation is favorable for Rh. DFT calculations predict that the RhIII hydrides have much higher relative acidities than their Ir congeners (ΔpKa ≃ 7-8 in CH2Cl2), and are also more acidic than the strong acid [H(OEt2)2][B(C6F5)4].

Pro-B-cell-specific transcription and proapoptotic function of protein kinase Ceta.

Using a subtractive cloning scheme on cDNA prepared from primary pro-B and pre-B cells, we identified several genes whose products regulate apoptosis. We further characterized one of these genes, encoding protein kinase Ceta (PKCeta). PKCeta transcripts were readily detected in pro-B cells but were absent in pre-B cells. Although both a full-length and a truncated form of PKCeta were detectable in bone marrow pro-B cells, transition to the pre-B-cell stage was associated with increased relative levels of truncated PKCeta. We found that PKCeta is proteolyzed in apoptotic lymphocytes, generating a kinase-active fragment identical to the truncated form which is capable of inducing apoptosis when expressed in a pro-B cell line. Caspase-3 can generate an identical PKCeta cleavage product in vitro, and caspase inhibitors prevent the generation of this product during apoptosis in transfected cell lines. Inducible overexpression of either the full-length or truncated form of PKCeta results in cell cycle arrest at the G(1)/S transition. These results suggest that the expression and proteolytic activation of PKCeta play an important role in the regulation of cell division and cell death during early B-cell development.

The purification of B-cell precursors from mouse fetal liver.

Lymphocyte progenitor cells isolated on sequential days of gestation from mouse fetal liver represent distinct stages in B cell development. We have utilized polymerase chain reaction (PCR)-based assays to detect immunoglobulin (Ig) gene rearrangement and flow cytometry to assay cell surface markers following fractionation based on the differential expression of the B cell-specific phosphatase CD45 (B220). The purification of B220+ cells from day 17 fetal liver resulted in a 10-fold enrichment of cells which had undergone gene rearrangement events. We have also shown that day 13 fetal liver cells activate successive Ig gene rearrangements during short-term culture in the presence of fetal calf serum (FCS), interleukin-3 (IL3), and interleukin-7 (IL7). However, partially purified lymphocyte precursors fail to activate Ig gene rearrangement in culture unless they are cultured in the presence of a stromal cell line.

Supraspinal nocifensive responses of cats: spinal cord pathways, monoamines, and modulation.

These experiments were conducted to determine (1) whether dorsal and ventral ascending spinal pathways can each mediate unlearned supraspinal nocifensive responses of cats to noxious thermal stimuli and (2) whether interrupting the spinal projection of supraspinal monoaminergic neurons alters the excitability and natural modulation of these responses. In partially restrained cats, thermal pulses (greater than or equal to 47 degrees C) delivered to the hindlimbs of intact cats or rostral to lesions of the thoracic spinal cord elicited abrupt body movements and interruption of eating (or of exploring for) liquified food. These electronically monitored responses automatically terminated the stimulus. Natural modulation of responsiveness was produced by delivering food and thermal stimuli simultaneously; this reduced response probability by an average of 41%. Complete transection of the thoracic spinal cord eliminated both thermally elicited responses and orienting responses to noxious and tactile mechanical stimulation of the hindlimbs. Ventral bilateral thoracic spinal cord lesions that spared only the dorsal funiculus and portions of the dorsolateral funiculus (three cats) significantly reduced orienting responses to all mechanical hindlimb stimuli and reduced, but did not eliminate, movement and interrupt responses to noxious thermal hindlimb stimuli. Response latency was unaffected. Food-induced response suppression persisted although lumbar spinal cord concentrations of serotonin (5HT) and norepinephrine (NE) were markedly reduced. A bilateral lesion of the dorsal funiculi and dorsal portions of the dorsolateral funiculi (one cat) also reduced nocifensive responsiveness, but only the NE concentration in lumbar spinal cord was reduced significantly relative to a matched cervical sample. In contrast, deep bilateral lesions of the dorsolateral funiculi (two cats) produced an increase in the probability of movement and interrupt responses without affecting either response latency or food-induced response suppression. Lumbar spinal cord concentrations of NE and, in one cat, 5HT were reduced. We conclude that (1) the dorsal and ventral spinal funiculi are each sufficient to initiate and necessary to maintain normal supraspinally organized nocifensive behavior in the cat; (2) descending monoaminergic pathways are not necessary for the phasic modulation of these responses; and (3) the tonic excitability, but not the phasic modulation, of these responses is determined in part by fibers in the dorsolateral funiculus.

Pain-related laser-evoked potentials in awake monkeys: identification of components, behavioral correlates and drug effects.

Cutaneous stimulation with CO2 laser pulses activates small diameter sensory afferents and evokes a pain-related potential best recorded from the vertex (Cz) of humans. We report here the first successful recording of pain-related laser evoked potentials (LEPs) from awake monkeys. Laser pulses with stimulus intensities adjusted to the lowest level giving reproducible cerebral responses were delivered to the shaved tail of three awake African green monkeys. The proximal and distal tail were stimulated to calculate the conduction velocity of the activated fibers. The effects of subcutaneous injections of morphine and cocaine on the LEPs were evaluated. The results indicate that reproducible LEPs, with a morphology similar to those obtained from humans, can be recorded from the awake monkey. The calculated conduction velocity of the activated fibers averaged 8.7 m/s, which is in the range of A delta fibers. Following subcutaneous morphine injections, the LEPs disappeared and were quickly restored to their baseline amplitude following administration of naloxone. Cocaine administered subcutaneously led to a significant attenuation of LEP amplitudes without producing behavioral sedation. These findings suggest that the LEPs recorded from monkeys represent analgesic-sensitive, nociceptive-related potentials similar to those recorded from humans.

Topical capsaicin selectively attenuates heat pain and A delta fiber-mediated laser-evoked potentials.

Cutaneous stimulation with CO2 laser pulses activates A delta of nociceptive afferents and evokes late cerebral potentials (LEPs), the amplitude of which correlates parametrically with the perceived magnitude estimation of laser pulses. Capsaicin is known to desensitize the nociceptive terminals of C fibers. In this double-blind, vehicle-controlled experiment, we tested the hypothesis that topical capsaicin would inactivate A delta afferents and lead to an attenuation of the LEPs. Subjects applied capsaicin cream to the dorsum of one hand and vehicle cream to the other 3 times daily for a period of 5 weeks. At weekly intervals before starting, during administration and after discontinuation of capsaicin, LEPs were recorded and psychophysical thresholds and magnitude estimation for several sensory modalities were determined. The results of this study showed that topical capsaicin significantly and reversibly decreased the magnitude estimation of suprathreshold heat pain, laser pulses and amplitude of the LEPs. There was no statistically significant difference in light touch, deep pain and mechanical pain detection thresholds between the capsaicin- and vehicle-treated hands. It indicated that topical capsaicin caused a definite functional and reversible inactivation of A delta nociceptive afferent transmission. The decline in the magnitude estimation of laser pulses concomitantly with the attenuation of LEP amplitudes supports the hypothesis that some A delta afferents mediate noxious heat in humans. These findings demonstrate the usefulness of LEP in the physiological evaluation of nociceptive pathways and its potential usefulness in objectively documenting the effect of pharmacological treatment on pain perception.

Bilateral behavioral and regional cerebral blood flow changes during painful peripheral mononeuropathy in the rat.

A unilateral chronic constriction injury (CCI) of the sciatic nerve produced bilateral effects in both pain related behaviors and in the pattern of forebrain activation. All CCI animals exhibited spontaneous pain-related behaviors as well as bilateral hyperalgesia and allodynia after CCI. Further, we identified changes in baseline (unstimulated) forebrain activation patterns 2 weeks following CCI by measuring regional cerebral blood flow (rCBF). Compared to controls, CCI consistently produced detectable, well-localized and typically bilateral increases in rCBF within multiple forebrain structures in unstimulated animals. For example, the hindlimb region of somatosensory cortex was significantly activated (22%) as well as multiple thalamc nuclei, including the ventral medial (8%), ventral posterior lateral (10%) and the posterior (9%) nuclear groups. In addition, several forebrain regions considered to be part of the limbic system showed pain-induced changes in rCBF, including the anterior dorsal nucleus of the thalamus (23%), cingulate cortex (18%), retrosplenial cortex (30%), habenular complex (53%), interpeduncular nucleus (45%) and the paraventricular nucleus of the hypothalamus (30%). Our results suggest that bilateral somatosensory and limbic forebrain structures participate in the neural mechanisms of prolonged persistent pain produced by a unilateral injury.

Gender differences in pain perception and patterns of cerebral activation during noxious heat stimulation in humans.

The purpose of the present study was to determine whether gender differences exist in the forebrain cerebral activation patterns of the brain during pain perception. Accordingly, positron emission tomography (PET) with intravenous injection of H2(15)O was used to detect increases in regional cerebral blood flow (rCBF) in normal right-handed male and female subjects as they discriminated differences in the intensity of innocuous and noxious heat stimuli applied to the left forearm. Each subject was instructed in magnitude estimation based on a scale for which 0 indicated 'no heat sensation'; 7, 'just barely painful' and 10, 'just barely tolerable'. Thermal stimuli were 40 degrees C or 50 degrees C heat, applied with a thermode as repetitive 5-s contacts to the volar forearm. Both male and female subjects rated the 40 degrees C stimuli as warm but not painful and the 50 degrees C stimuli as painful but females rated the 50 degrees C stimuli as significantly more intense than did the males (P=0.0052). Both genders showed a bilateral activation of premotor cortex in addition to the activation of a number of contralateral structures, including the posterior insula, anterior cingulate cortex and the cerebellar vermis, during heat pain. However, females had significantly greater activation of the contralateral prefrontal cortex when compared to the males by direct image subtraction. Volume of interest comparison (t-statistic) also suggested greater activation of the contralateral insula and thalamus in the females (P < 0.05). These pain-related differences in brain activation may be attributed to gender, perceived pain intensity, or to both factors.

Regional changes in forebrain activation during the early and late phase of formalin nociception: analysis using cerebral blood flow in the rat.

This is the first neural imaging study to use regional cerebral blood flow (rCBF) in an animal model to identify the patterns of forebrain nociceptive processing that occur during the early and late phase of the formalin test. We measured normalized rCBF increases by an autoradiographic method using the radiotracer [99mTc]exametazime. Noxious formalin consistently produced detectable, well-localized and typically bilateral increases in rCBF within multiple forebrain structures, as well as the interpeduncular nucleus (Activation Index, AI = 66) and the midbrain periaqueductal gray (AI = 20). Structures showing pain-induced changes in rCBF included several forebrain regions considered part of the limbic system. The hindlimb region of somatosensory cortex was significantly activated (AI = 31), and blood flow increases in VPL (AI = 8.7) and the medial thalamus (AI = 9.0) exhibited a tendency to be greater in the late phase as compared to the early phase of the formalin test. The spatial pattern and intensity of activation varied as a function of the time following the noxious formalin stimulus. The results highlight the important role of the limbic forebrain in the neural mechanisms of prolonged persistent pain and provide evidence for a forebrain network for pain.

Laser-evoked cerebral potentials and sensory function in patients with central pain.

Central pain syndromes (CPS) could be caused by disinhibition of spinothalamic excitability or by other central nervous system (CNS) changes caused by reduced spinothalamic function. To examine these possibilities, we studied 11 patients (ages 51-82 years) with unilateral central pain and with reproducible cerebral evoked vertex potentials in response to cutaneous stimulation of the normal side with pulses from an infra-red CO2 laser. All patients had normal tactile and kinesthetic sensation; one had slightly decreased vibratory sense bilaterally. All showed, from the unaffected (asymptomatic) side, laser evoked potentials (LEPs) with negative (N) components ranging from 208 to 280 msec peak latency (av: 240 +/- 6 SE msec) and peak amplitudes of 1-7 microV (av: 2.9 +/- 0.5 SE microV), followed, in all but 1 patient, by positive (P) potentials ranging from 288 to 370 msec peak latency (av: 319 +/- 7.7 SE msec) with peak amplitudes of 1-7 microV (2.8 +/- 0.5 SE microV). Laser stimulation of the affected (symptomatic) side in 5 patients evoked LEPs with N-P interpeak amplitudes that were within 20% of those evoked from the normal side. All but one of these patients had thresholds for warm, heat pain, and deep pain that were normal in comparison with the unaffected side. The excepted patient had the largest N-P interpeak amplitude asymmetry (18.5%) of this group. Ratings of laser pulse intensity were either symmetrical (n = 2) or increased on the affected side (n = 3) in these patients. In contrast, laser stimulation of the affected side failed to evoke either N or P potentials in 6 patients, all of whom had lateralized increased thresholds for warm, heat pain, or deep pain, or reduced ratings of laser pulse sensation. Although 1 patient had increased ratings of laser pulse sensation, the amplitude of the LEP was always reduced on the side of increased pain or heat threshold in these CPS patients (Fisher exact test: P = 0.015). These results reflect primarily a deficit in spinothalamic tract function and do not suggest excessive CNS responses to synchronous activation of cutaneous heat nociceptors in patients with CPS.

Effect of medial bulboreticular and raphe nuclear lesions on the excitation and modulation of supraspinal nocifensive behaviors in the cat.

Six cats were trained to eat while partially restrained and while thermal pulse stimuli (43-60 degrees C, 5 s duration) were delivered to the upper hindlimbs. Food and stimulus delivery were under programmed electronic control. The probability and latency of 3 natural, unlearned nocifensive behaviors were electronically registered: interruption of eating or of exploring for food, hindlimb movement and vocalization. Preoperatively, all cats showed significant increases in the probability of two or more behaviors as stimulus temperature increased. Each cat also showed a significant food-induced suppression of one or more of these behaviors. Thermocoagulation lesions limited to the giganto- and magnocellular fields of the medial medullary reticular formation (4 cats) produced a decrease in nocifensive responsiveness. Larger lesions within the same area but with extension into the postpyramidal raphe nuclei, resulted in increased nocifensive responsiveness (2 cats). No lesion affected response latency or the food-induced modulation of nocifensive behavior. The results support the hypothesis that supraspinally organized nocifensive responses are: (1) tonically facilitated by neural activity originating in or passing through the medial bulboreticular formation; (2) tonically suppressed by midline raphe spinal neurons; and (3) phasically modulated by suprabulbar neural mechanisms that are related to changes in behavioral state.

Differential effects of chronic partial myelotomies on monoamine levels in cat spinal cord.

The concentrations of 5-hydroxytryptamine (5-HT), norepinephrine (NE) and dopamine (DA) were measured in samples of lumbar and cervical spinal cords from 6 cats with chronic (over 2 months) lesions of the thoracic spinal cord and from 7 unoperated cats. Lesions confined to the dorsal thoracic spinal cord significantly lowered lumbar concentrations of NE, but not 5-HT, compared with control lumbar or matched paired cervical samples. Both NE and 5-HT were significantly reduced by dorsal or ventral lesions that involved tissue ventral to the central canal. Only the largest lesion could be shown to reduce lumbar DA concentration.

The effect of systemic cocaine on the responses to noxious stimuli and spontaneous activity of medial bulboreticular projection neurons.

The effect of antinociceptive doses of cocaine (25 mg/kg, i.p.) on unit responses to noxious somatic stimuli and spontaneous activity of antidromically identified projection neurons in the medial medullary reticular formation (MRF) was studied in the rat. Thirty-three antidromically activated neurons were recorded from the medullary raphe, gigantocellular, or paragigantocellular nuclei in an acute anaesthetized preparation; 25 cells projected to the spinal cord and 8 neurons had rostral projections through the medial forebrain bundle (n = 4) or the medial thalamus (n = 4). After cocaine administration, 24 (73%) of these cells showed immediate (less than 5 min) and prolonged (45-70 min) increases in their level of spontaneous activity. Associated with this increased interstimulus activity, 21 of 29 (72%) neurons responsive to noxious somatic stimulation reduced their responsiveness, relative to prestimulus activity, after cocaine administration. In 5 animals tested, the cocaine-induced changes in spontaneous activity and changes in evoked responsiveness were unaffected by naloxone (1 mg/kg, i.p.) but partially reversed within 5 min of the administration of chlorpromazine (3 mg/kg, i.p.). There were no obvious differences in neuronal response characteristics or the effect of cocaine that correlated with anatomical location or direction of axonal projection. Similar results were obtained while recording from 14 somatically responsive units in chronic, unrestrained, lightly anesthetized or awake rats. These findings provide direct evidence that cocaine, in doses that are antinociceptive for the rat, affects both unit responses to noxious stimuli and the spontaneous activity of caudally and rostrally projecting bulboreticular neurons over a time course that parallels the behavioral antinociception. The observation that unit responses to somatic stimuli were reduced while spontaneous activity was unchanged or increased in most cells suggests that cocaine antinociception may be due to the activation of sensory inhibitory mechanisms mediated by the MRF.

The effect of systemic cocaine on spontaneous and nociceptively evoked activity of neurons in the medial and lateral thalamus.

In rats, analgesic doses of cocaine (25 mg/kg, i.p.) suppressed the responses of 20 of 22 medial and lateral thalamic neurons to reticular formation and somatic noxious stimuli. The responses of 7 of 8 lateral thalamic neurons to innocuous somatic stimuli were unaffected or enhanced. The suppression of thalamic responses to noxious stimuli may be part of the mechanism underlying cocaine analgesia.

The effect of systemic cocaine on spinal nociceptive reflex activity in the rat.

In the anesthetized rat, cocaine (25 mg/kg i.p.), enhanced the frequency potentiation of nociceptively evoked polysynaptic discharges but did not affect the polysynaptic reflex discharge to single nociceptive stimuli or the habituation of this reflex to repetitive pinch stimuli. The non-nociceptive, short-latency reflex discharge was suppressed for 10-15 min after cocaine administration. The neurogenic extravasation response to antidromic cutaneous C-fiber stimulation was unaffected by cocaine. These findings suggest that systemic cocaine, in doses analgesic for the rat, does not suppress spinal nociceptive reflexes.

Cocaine: evidence for supraspinal, dopamine-mediated, non-opiate analgesia.

Cocaine (25 mg/kg i.p.) produces analgesia in the rat within 5 min and for a duration of 90 min as determined by the formalin test or for 30 min as determined by the hot plate test. Cocaine analgesia is unaffected by doses of naloxone that are sufficient to attenuate morphine analgesia in both tests. Chlorpromazine (3 mg/kg i.p.), SCH 23390 (100 micrograms/kg i.p.; a D1 dopamine receptor antagonist), and eticlopride (75 micrograms/kg i.p.; a D2 dopamine receptor antagonist) each attenuate cocaine analgesia in both tests at doses that alone do not affect performance in either test. Measurements of blood pressure and heart rate indicate that cocaine analgesia is not due to the activation of baroreceptor reflex afferents. We conclude that cocaine is a supraspinally acting, dopamine-mediated, non-opiate analgesic in the rat.

Neurophysiological, pharmacological and behavioral evidence for medial thalamic mediation of cocaine-induced dopaminergic analgesia.

These studies examined the effects of cocaine on thalamic neurons that respond maximally either to noxious or to innocuous somatic stimulation. Cocaine attenuated high intensity electrically-evoked nociceptive responses of all 25 units studied in the parafascicular and central lateral nuclei of the medial thalamus. A dose of 1 mg/kg intravenously (i.v.) suppressed medial thalamic unit discharge evoked by both noxious somatic stimulation (49.4 +/- 8.7% of control response) and spinal cord stimulation (76.2 +/- 6.6% of control response). The effect of cocaine on unit responses to noxious somatic stimulation was dose-related in the range of 0.3-3.5 mg/kg i.v. and was attenuated by eticlopride, a D-2 selective dopamine receptor antagonist. Morphine also suppressed noxious somatic evoked responses of medial thalamic units in a dose-dependent manner. Units in the lateral (ventrobasal) thalamus (n = 4) that responded only to innocuous stimuli were not affected by cocaine at doses up to 3.5 mg/kg i.v. Ibotenic acid lesions in the parafascicular nucleus of the medial thalamus attenuated the analgesic effect of cocaine in the formalin test. These results suggest that both cocaine and the parafascicular nucleus interact with dopaminergic mechanisms that attenuate nociceptive spinal projections to the medial thalamus.

Spinal antinociception mediated by a cocaine-sensitive dopaminergic supraspinal mechanism.

The role of dopaminergic descending supraspinal processes in mediating the antinociceptive action of cocaine was studied in the rat using a combination of extracellular neuronal recording and behavioral techniques. Neurons in the superficial laminae (I-II) of the spinal dorsal horn with receptive fields on the tail were recorded in anesthetized rats using insulated metal microelectrodes. Stimulation of the receptive field with either high intensity transcutaneous electrical pulses or with an infrared CO2 laser beam produced a biphasic increase in dorsal horn unit discharge. Conduction velocity estimates indicated that the early discharge corresponded to activity in A delta whereas the late response corresponded to activity in C afferent fibers. Cumulative doses of cocaine (0.1-3.1 mg/kg i.v.) inhibited the late response to either electrical or laser stimulation in a dose-related manner. The early response to laser, but not electrical, stimulation was also suppressed by cocaine. Neurons in the spinal dorsal horn with receptive fields on the ipsilateral hindpaw were activated by natural noxious (pinch) or innocuous (tap) somatic stimulation. Cocaine selectively suppressed nociceptively evoked dorsal horn unit discharge. This antinociceptive effect was dose-related (0.3-3.1 mg/kg, i.v.) and antagonized by eticlopride (0.05-0.1 mg/kg, i.v.), a selective D2 dopamine receptor blocker. The same doses of cocaine failed to inhibit the responses of dorsal horn neurons to low threshold innocuous stimulation. Complete thoracic spinal cord transection eliminated the antinociceptive effect of cocaine on dorsal horn neurons and also eliminated the cocaine-induced attenuation of the tail-flick reflex.(ABSTRACT TRUNCATED AT 250 WORDS)