Increased extracellular glutamate evoked by 1-methyl-4-phenylpyridinium [MPP(+)] in the rat striatum is not essential for dopaminergic neurotoxicity and is not derived from released glutathione

A number of studies have implicated the interactions of the excitatory amino acid L-glutamate (Glu) with its ionotropic and metabotropic receptors as important components of the mechanism underlying the dopaminergic neurotoxicity of 1-methyl-4-phenylpyridinium [MPP(+)]. Furthermore, microdialysis experiments have demonstrated that perfusion of relatively high concentrations of MPP(+) into the rat striatum evoke a delayed, massive release of Glu. Interestingly, perfusion of MPP(+) also mediates a similar release of glutathione (GSH). Together, these observations raise the possibility that the rise of extracellular Glu mediated by MPP(+) may be the result of hydrolysis of released GSH by gamma-glutamyl transpeptidase (gamma-GT). In the present investigation it is demonstrated that perfusions of solutions of 0.7 and 1.3 mM MPP(+) dissolved in artificial cerebrospinal fluid into the rat striatum evoke neurotoxic damage to dopaminergic terminals, assessed by both a two-day test/challenge procedure and tyrosine hydroxylase immunoreactivity, but without the release of Glu. Perfusions of 2.5 mM MPP(+) cause more extensive dopaminergic neurotoxicity and a dose-dependent release of Glu. However, neither this release of Glu nor MPP(+)-induced dopaminergic neurotoxicity are blocked by the irreversible gamma-GT inhibitor acivicin. Together, these observations indicate that a rise of extracellular levels of Glu is not essential for the dopaminergic neurotoxicity of MPP(+). Furthermore, the rise of extracellular Glu caused by perfusion of 2.5 mM MPP(+) is not the result of the gamma-GT-mediated hydrolysis of released GSH. It is possible that the rise of extracellular levels of Glu, L-aspartate, L-glycine and L-taurine evoked by perfusions of 2.5 mM MPP(+) into the rat striatum may reflect, at least in part, the release of these amino acids from astrocytes.

Flux conversion and evidence of relaxation in a high-beta plasma formed by high-speed injection into a mirror confinement structure

High-beta plasmoids can survive the violent dynamics of supersonic reflection off mirror structures, producing a stable high-beta field-reversed configuration (FRC). This shows both the robustness of FRCs and their tendency to assume a preferred plasma state, possibly conforming to a relaxation principle. The key observations are (1) approximate preservation of the magnetic helicity, (2) substantial conversion from toroidal to poloidal magnetic flux, (3) substantial toroidal flow, and (4) a high-beta quiescent final state. These results are from the Translation, Confinement, and Sustainment experiment where a disorganized plasmoid is injected at super-Alfvenic speed into a confinement chamber. After successive reflections from end mirrors, the plasmoid settled into a near-FRC state with high beta and low toroidal magnetic field. The flux conversion and helicity preservation are inferred by an interpretive model.

Tobacco use among high school athletes and nonatieletes: results of the 1997 youth risk behavior survey

In the United States today, the use of tobacco has become an entrenched part of teenage culture. The present study used the 1997 Youth Risk Behavior Survey (YRBS), which collected data from a nationally representative sample of 16,262 students in public and private high schools, to compare the tobacco use patterns of athletes and nonathletes. The independent variable, athletic participation, differentiated between moderately involved (1 or 2 teams) and highly involved (3 or more teams) athletes. Frequency of cigarette and cigar smoking and smokeless tobacco use served as the operational measure of tobacco use. Age, race/ethnicity, parental education, and residence were controlled. Logistic regression was used to calculate odds ratios for female and male athletes and nonathletes for each of the tobacco use variables. It was found that both male and female athletes were less likely to have ever smoked regularly, the effect being stronger for more highly involved athletes of both genders. Cigar smoking was unrelated to athlete status. Both female and male athletes were more likely to have used smokeless tobacco, the effect being stronger for more highly involved athletes of both genders. The findings are discussed in terms of access to health information, performance considerations, social status factors, the salience of an athletic identity, and the influence of the athletic subculture on its members.

Challenges in pain management at the end of life

Effective pain management in the terminally ill patient requires an understanding of pain control strategies. Ongoing assessment of pain is crucial and can be accomplished using various forms and scales. It is also important to determine if the pain is nociceptive (somatic or visceral pain) or neuropathic (continuous dysesthesias or chronic lancinating or paroxysmal pain). Nociceptive pain can usually be controlled with nonsteroidal antiinflammatory drugs or corticosteroids, whereas neuropathic pain responds to tricyclic antidepressants or anticonvulsants. Relief of breakthrough pain requires the administration of an immediate-release analgesic medication. If a significant amount of medication for breakthrough pain is already being given, the baseline dose of sustained-release analgesic medication should be increased. If pain does not respond to one analgesic medication, physicians should use an equianalgesic dose chart when changing the medication or route of administration. Opioid rotation can be used if pain can no longer be controlled on a specific regimen. The impact of unresolved psychosocial or spiritual issues on pain management may need to be addressed.

Responses and afferent pathways of superficial and deeper c(1)-c(2) spinal cells to intrapericardial algogenic chemicals in rats

Electrical stimulation of vagal afferents or cardiopulmonary sympathetic afferent fibers excites C(1)--C(2) spinal neurons. The purposes of this study were to compare the responses of superficial (depth <0.35 mm) and deeper C(1)--C(2) spinal neurons to noxious chemical stimulation of cardiac afferents and determine the relative contribution of vagal and sympathetic afferent pathways for transmission of noxious cardiac afferent input to C(1)--C(2) neurons. Extracellular potentials of single C(1)--C(2) neurons were recorded in pentobarbital anesthetized and paralyzed male rats. A catheter was placed in the pericardial sac to administer a mixture of algogenic chemicals (0.2 ml) that contained adenosine (10(-3) M), bradykinin, histamine, serotonin, and prostaglandin E(2) (10(-5) M each). Intrapericardial chemicals changed the activity of 20/106 (19%) C(1)--C(2) spinal neurons in the superficial laminae, whereas 76/147 (52%) deeper neurons responded to cardiac noxious input (P < 0.01). Of 96 neurons responsive to cardiac inputs, 48 (50%) were excited (E), 41 (43%) were inhibited (I), and 7 were excited/inhibited (E-I) by intrapericardial chemicals. E or I neurons responsive to intrapericardial chemicals were subdivided into two groups: short-lasting (SL) and long-lasting (LL) response patterns. In superficial gray matter, excitatory responses to cardiac inputs were more likely to be LL-E than SL-E neurons. Mechanical stimulation of the somatic field from the head, neck, and shoulder areas excited 85 of 95 (89%) C(1)--C(2) spinal neurons that responded to intrapericardial chemicals; 31 neurons were classified as wide dynamic range, 49 were high threshold, 5 responded only to joint movement, and no neuron was classified as low threshold. For superficial neurons, 53% had small somatic fields and 21% had bilateral fields. In contrast, 31% of the deeper neurons had small somatic fields and 46% had bilateral fields. Ipsilateral cervical vagotomy interrupted cardiac noxious input to 8/30 (6 E, 2 I) neurons; sequential transection of the contralateral cervical vagus nerve (bilateral vagotomy) eliminated the responses to intrapericardial chemicals in 4/22 (3 E, 1 I) neurons. Spinal transection at C(6)--C(7) segments to interrupt effects of sympathetic afferent input abolished responses to cardiac input in 10/10 (7 E, 3 I) neurons that still responded after bilateral vagotomy. Results of this study support the concept that C(1)-C(2) superficial and deeper spinal neurons play a role in integrating cardiac noxious inputs that travel in both the cervical vagal and/or thoracic sympathetic afferent nerves.

Backbone dynamics of the calcium-signaling protein apo-S100B as determined by 15N NMR relaxation

Backbone dynamics of homodimeric apo-S100B were studied by (15)N nuclear magnetic resonance relaxation at 9.4 and 14.1 T. Longitudinal relaxation (T(1)), transverse relaxation (T(2)), and the (15)N-[(1)H] NOE were measured for 80 of 91 backbone amide groups. Internal motional parameters were determined from the relaxation data using the model-free formalism while accounting for diffusion anisotropy. Rotational diffusion of the symmetric homodimer has moderate but statistically significant prolate axial anisotropy (D( parallel)/D( perpendicular) = 1.15 +/- 0.02), a global correlation time of tau(m) = 7.80 +/- 0.03 ns, and a unique axis in the plane normal to the molecular symmetry axis. Of 29 residues at the dimer interface (helices 1 and 4), only one has measurable internal motion (Q71), and the order parameters of the remaining 28 were the highest in the protein (S(2) = 0.80 to 0.91). Order parameters in the typical EF hand calcium-binding loop (S(2) = 0.73 to 0.87) were slightly lower than in the pseudo-EF hand (S(2) = 0.75 to 0.89), and effective internal correlation times, tau(e), distinct from global tumbling, were detected in the calcium-binding loops. Helix 3, which undergoes a large, calcium-induced conformational change necessary for target-protein binding, does not show evidence of interchanging between the apo and Ca(2+)-bound orientations in the absence of calcium but has rapid motion in several residues throughout the helix (S(2) = 0.78 to 0.88; 10 < or = tau(e) < or = 30 ps). The lowest order parameters were found in the C-terminal tail (S(2) = 0.62 to 0.83). Large values for chemical exchange also occur in this loop and in regions nearby in space to the highly mobile C-terminal loop, consistent with exchange broadening effects observed.

Spinal taurine levels are increased 7 and 30 days following methylprednisolone treatment of spinal cord injury in rats

The amino acid taurine serves many functions in the nervous system serving as inhibitory neurotransmitter/neuromodulator, neurotrophin, antioxidant, and osmolyte. Taurine levels are increased following brain injury and glucocorticoid administration. Thus, the purpose of this study was to examine spinal taurine concentrations following spinal cord injury (SCI) and methylprednisolone (MP) treatment of SCI. A total of 44 adult male Sprague-Dawley rats were divided into control and lesion groups. Control rats received a T6 vertebral laminectomy while lesioned rats received a laminectomy followed by complete spinal transection. Half of the animals in each group received MP intravenously following sham-operation or SCI. Rats survived for 7 or 30 days and concentrations of taurine in spinal gray and white matter, in spinal segments both near and distant from the injury epicenter, were resolved by HPLC analysis. Taurine levels were increased 7 and 30 days following transection in spinal segments immediately adjacent to the lesion and were further elevated by MP treatment. No increases were seen in far rostral/caudal segments, and MP treatment alone had no effect on spinal taurine levels. These findings demonstrate that spinal injury results in increased taurine concentrations in spinal segments undergoing the greatest degree of cellular reactivity and tissue reorganization and that MP therapy potentiates these increases. These findings are significant in that they further characterize the effects of acute MP therapy in spinal tissue. Since taurine is thought to be involved in neuroprotection and/or regeneration following injury, the potentiation of taurine levels by MP treatment may relate to its therapeutic properties.

Glutamine synthetase activities in spinal white and gray matter 7 days following spinal cord injury in rats

The glial enzyme glutamine synthetase (GS) is critical for central nervous system catabolism of glutamate and glutamine production. Upregulation of GS is a hallmark of reactive astrocytosis, although such induction following spinal cord injury (SCI) has not been reported. This study's purpose was to determine if GS activity is increased following SCI. Experimental rats received a complete spinal transection at the T5 segment and control rats received a laminectomy only. GS activities were determined using an enzymatic microassay. Glutamine levels were resolved in semi-adjacent sections. At 7 days following SCI, GS activity increased an average of 170-190% in white matter and 15-25% in gray matter immediately adjacent to the transection, and 70-90% in white matter and 40-45% in gray matter from cervical and lumbar enlargements. Correlative increases in glutamine were observed also. These findings further characterize the astrocytic response to SCI, which may contribute to altered glutamine metabolism in injured spinal tissue.

Enhanced confinement and stability of a field-reversed configuration with rotating magnetic field current drive

A new experiment has been constructed to study the sustainment of a field-reversed configuration (FRC) with a rotating magnetic field (RMF). FRCs were formed with cold, unmagnetized ions and thus without a kinetic ion component that was believed to provide stability to internal tilt modes. No destructive instabilities were observed for the RMF FRC. Only peripheral radial penetration of the RMF was observed. The radially inward flow arising from axial screening currents at the FRC edge reduced convective and conductive losses to the measurement limit of the diagnostics.

The geriatric patient: a systematic approach to maintaining health

The number of persons 65 years of age and older continues to increase dramatically in the United States. Comprehensive health maintenance screening of this population is becoming an important task for primary care physicians. As outlined by the U.S. Preventive Services Task Force, assessment categories unique to elderly patients include sensory perception and injury prevention. Geriatric patients are at higher risk of falling for a number of reasons, including postural hypotension, balance or gait impairment, polypharmacy (more than three prescription medications) and use of sedative-hypnotic medications. Interventional areas that are common to other age groups but have special implications for older patients include immunizations, diet and exercise, and sexuality. Cognitive ability and mental health issues should also be evaluated within the context of the individual patient's social situation-not by screening all patients but by being alert to the occurrence of any change in mental function. Using an organized approach to the varied aspects of geriatric health, primary care physicians can improve the care that they provide for their older patients.

Characterization of myosin V binding to brain vesicles

Myosin II and V are important for the generation and segregation of subcellular compartments. We observed that vesicular myosin II and V were associated with the protein scaffolding of a common subset of vesicles by density sedimentation, electron microscopy, and immunofluorescence. Solubilization of either myosin II or V was caused by polyphosphates with the following efficacy at 10 mM: for myosin II ATP-Mg(2+) = ATP = AMP-PNP (5'-adenylyl imidodiphosphate) > pyrophosphate = tripolyphosphate > tetrapolyphosphate = ADP > cAMP = Mg(2+); and for myosin V pyrophosphate = tripolyphosphate > ATP-Mg(2+) = ATP = AMP-PNP > ADP = tetrapolyphosphate > cAMP = Mg(2+). Consequently, we suggest solubilization was not an effect of phosphorylation, hydrolysis, or disassociation of myosin from actin filaments. Scatchard analysis of myosin V binding to stripped dense vesicles showed saturable binding with a K(m) of 10 nM. Analysis of native vesicles indicates that these sites are fully occupied. Together, these data show there are over 100 myosin Vs/vesicle (100-nm radius). We propose that polyphosphate anions bind to myosin II and V and induce a conformational change that disrupts binding to a receptor.

Update on the prevention and treatment of sexually transmitted diseases

The Centers for Disease Control and Prevention updated its guidelines for the treatment of sexually transmitted diseases. The guidelines include the following information: recommendations for hepatitis A immunization and expanded indications for hepatitis B vaccination; updated diagnostic criteria for pelvic inflammatory disease and parenteral treatment regimens; information on two additional antiviral agents for the treatment of genital herpes; a recommendation for use of a single 1-g dose of azithromycin (Zithromax) to treat urethritis and chlamydial cervicitis; information on the use of quinolones in the treatment of gonococcal infections; information on podofilox and imiquimod, which are both patient-applied medications, in the treatment of noncervical human papillomavirus infection; updated guidelines for the prevention and detection of congenital syphilis; and information on how to prevent the spread of sexually transmitted diseases by educating patients about the importance of changing their sexual behaviors. To have a significant impact on the current rate of transmission of sexually transmitted diseases, family physicians should develop a plan to integrate the guidelines into their practices.

Chemical activation of cervical cell bodies: effects on responses to colorectal distension in lumbosacral spinal cord of rats

We have shown that stimulation of cardiopulmonary sympathetic afferent fibers activates relays in upper cervical segments to suppress activity of lumbosacral spinal cells. The purpose of this study was to determine if chemical excitation (glutamate) of upper cervical cell bodies changes the spontaneous activity and evoked responses of lumbosacral spinal cells to colorectal distension (CRD). Extracellular potentials were recorded in pentobarbital-anesthetized male rats. CRD (80 mmHg) was produced by inflating a balloon inserted in the descending colon and rectum. A total of 135 cells in the lumbosacral segments (L(6)-S(2)) were activated by CRD. Seventy-five percent (95/126) of tested cells received convergent somatic input from the scrotum, perianal region, hindlimb, and tail; 99/135 (73%) cells were excited or excited/inhibited by CRD; and 36 (27%) cells were inhibited or inhibited/excited by CRD. A glutamate (1 M) pledget placed on the surface of C(1)-C(2) segments decreased spontaneous activity and excitatory CRD responses of 33/56 cells and increased spontaneous activity of 13/19 cells inhibited by CRD. Glutamate applied to C(6)-C(7) segments decreased activity of 10/18 cells excited by CRD, and 9 of these also were inhibited by glutamate at C(1)-C(2) segments. Glutamate at C(6)-C(7) increased activity of 4/6 cells inhibited by CRD and excited by glutamate at C(1)-C(2) segments. After transection at rostral C(1) segment, glutamate at C(1)-C(2) still reduced excitatory responses of 7/10 cells. Further, inhibitory effects of C(6)-C(7) glutamate on excitatory responses to CRD still occurred after rostral C(1) transection but were abolished after a rostral C(6) transection in 4/4 cells. These data showed that C(1)-C(2) cells activated with glutamate primarily produced inhibition of evoked responses to visceral stimulation of lumbosacral spinal cells. Inhibition resulting from activation of cells in C(6)-C(7) segments required connections in the upper cervical segments. These results provide evidence that upper cervical cells integrate information that modulates activity of distant spinal neurons responding to visceral input.

Nerve growth factor-induced stimulation of dorsal root ganglion/spinal cord co-grafts in oculo: enhanced survival and growth of CGRP-immunoreactive sensory neurons

Intraocular co-grafts of rat fetal spinal cord and dorsal root ganglia were used to examine the enhanced survival, growth, and differentiation of sensory neurons by nerve growth factor. E14 lumbar spinal segments were implanted into the anterior eye chamber of capsaicin-pretreated rats. Two weeks later, an E14 dorsal root ganglion was implanted beside the spinal cord graft. Nerve growth factor or vehicle was injected weekly for 4 weeks into the anterior eye chamber. Co-grafts were examined weekly and, at 6 weeks, processed for calcitonin gene-related peptide (CGRP) immunofluorescence. No differences in overall size were determined for the grafts. Co-grafts treated with nerve growth factor contained many more CGRP neurons (19.4 cells/20 microm) that were significantly larger (mean 764 microm2) than neurons from control co-grafts (8.6 cells/20 microm; mean 373 microm2). In co-grafts treated with nerve growth factor, CGRP-immunoreactive fibers were extensive in the dorsal root ganglion, adjacent iris, and spinal cord compared to control co-grafts. A few CGRP-positive motoneurons were observed in the spinal cord, but no differences in number or size of motoneurons were found. The current report demonstrates that spinal cord and dorsal root ganglia can be co-grafted in oculo for long periods of time. Many dorsal root ganglion neurons survive and send peripheral processes into the iris and central processes into the spinal cord under the influence of exogenous nerve growth factor. The intraocular graft paradigm can be of use to further examine the role of neurotrophic factors in regulating or modulating dorsal root ganglion and spinal cord neurons.

Outpatient detoxification of the addicted or alcoholic patient

Outpatient detoxification of patients with alcohol or other drug addiction is being increasingly undertaken. This type of management is appropriate for patients in stage I or stage II of withdrawal who have no significant comorbid conditions and have a support person willing to monitor their progress. Adequate dosages of appropriate substitute medications are important for successful detoxification. In addition, comorbid psychiatric, personality and medical disorders must be managed, and social and environmental concerns need to be addressed. By providing supportive, nonjudgmental, yet assertive care, the family physician can facilitate the best possible chance for a patient's successful recovery.

High school athletic participation, sexual behavior and adolescent pregnancy: a regional study

PURPOSE

To determine whether high school athletic participation among adolescents in Western New York was associated with reduced rates of sexual behavior and pregnancy involvement.

METHODS

A secondary analysis of data from the Family and Adolescent Study, a longitudinal study of a random sample of adolescents (ages 13-16 years) from 699 families living in households in Western New York. A general population sample was obtained with characteristics closely matching the census distributions in the area. Interview and survey methods provided data on athletic participation, frequency of sexual relations during the past year, and risk for pregnancy. Bivariate correlations were used to examine relationships among athletic participation, demographic and control variables, and measures of sexual behavior and pregnancy rates. Next, path analyses were done in order to test for hypothesized relationships between athletic participation, sexual behavior, and pregnancy involvement while controlling for age, race, income, family cohesion, and non-athletic forms of extracurricular activity. Variables that were significantly associated with sexual behavior and/or pregnancy involvement were presented for both sexes within the resulting multivariate models.

RESULTS

Lower income and higher rates of sexual activity were associated with higher rates of pregnancy involvement for both sexes. Family cohesion was associated with lower sexual activity rates for both sexes. For girls, athletic participation was directly related to reduced frequency of sexual behavior and, indirectly, to pregnancy risk. Male athletes did not exhibit lower rates of sexual behavior and involvement with pregnancy than male non-athletes. Boys who participated in the arts, however, did report lower rates of sexual behavior and, indirectly, less involvement with pregnancy.

CONCLUSIONS

Female adolescents who participated in sports were less likely than their non-athletic peers to engage in sexual activity and/or report a pregnancy. Among male adolescents, athletic participation was unrelated to sexual behavior and pregnancy involvement. Teen pregnancy prevention efforts for girls should consider utilizing sport as a strategic tool.

Sports, sexual behavior, contraceptive use, and pregnancy among female and male high school students: testing cultural resource theory

In this paper, we examine the relationships among athletic participation and sexual behavior, contraceptive use, and pregnancy in female and male high school students. Analyses of covariance and multiple analyses of covariance were performed on a nationally representative sample of 8,979 high school students (the 1995 Youth Risk Behavior Survey). After controlling for race and ethnicity, age, and mother’s education, girls who participated in sports had lower rates of sexual experience, fewer sex partners, later age of first intercourse, higher rates of contraceptive use, and lower rates of past pregnancy than girls who did not participate. Male high school athletes reported higher rates of sexual experience and more partners than nonathletes, but—like their female counterparts—were also more likely to have used birth control during their most recent intercourse. Cultural resource theory suggests that athletic participation may reduce girls’ adherence to conventional cultural scripts while providing them with additional social and personal resources on which to draw in the sexual bargaining process. Sports provides boys with similar resources while strengthening their commitment to traditional masculine scripts.

[The role of intra- and extracellular calcium sources in the rhythmic inotropic regulation of isometric contractions in the chick embryo myocardium]

Isometric contractions and force-frequency relationships (FFR) were assessed in isolated ventricular preparations of 3- and 4-day chick embryos (EM) and posthatched (PH) chicks. Pacing protocols for the FFR assessment were applied in normal buffer, buffer with 50% and 25% of normal Na+ concentration, and in buffer with ryanodine. PH myocardium showed greater peak force and more prominent FFR than EM. 50% low Na+ superfusion induced positive inotropic effect and increase in the FFR in PH and EM. 25% low Na+ superfusion induced negative inotropic effect and suppressed FFR more prominent in EM. Ryanodine more suppressed FFR in PH myocardium. The observed age-dependent differences substantiate the fact that Na-Ca exchange plays a leading role in the FFR regulation in early embryonic myocardium and sarcoplasmic reticulum plays a leading role in PH myocardium.

Propriospinal neurons in the C1-C2 spinal segments project to the L5-S1 segments of the rat spinal cord

Physiological studies indicate that neurons in the upper cervical spinal cord have descending projections to the lumbosacral spinal cord and mediate inhibition of dorsal horn neurons activated from afferent input. In the present study, retrograde tracing techniques were used to examine the distribution of propriospinal neurons in C1-C2 spinal segments that project to lumbosacral spinal segments. Fluorogold or horseradish peroxidase were injected unilaterally or bilaterally into the L5-S1 spinal segments. After 2-4 days, rats were perfused with fixative and C1-C2 spinal segments were processed for retrograde labeling. Numerous neurons were found in the C1-C2 segments. In unilaterally and bilaterally injected rats, retrogradely labeled neurons were located on both the ipsilateral and contralateral sides. Retrogradely labeled neurons were located in the following locations: lateral cervical and spinal nuclei, nucleus proprius, ventral horn and the central gray region (area X). These studies demonstrate a descending projection from C1-C2 segments to the lower lumbar and sacral spinal cord. We hypothesize that many of these C1-C2 propriospinal neurons are important in modulating responses of spinal neurons at lower segmental levels to various peripheral stimuli.

Apposition of enkephalin- and neurotensin-immunoreactive neurons by serotonin-immunoreactive varicosities in the rat spinal cord

The descending serotonergic system provides a powerful inhibitory input to the dorsal horn of the spinal cord. Little is known about the chemical identity of the spinal neurons that the serotonergic system innervates, although spinal enkephalinergic neurons are likely candidates. This study investigated the apposition of serotonin-immunoreactive varicosities onto enkephalin- and neurotensin-immunoreactive neurons in the rat lumbosacral spinal cord. Using a double immunofluorescence technique, serotonin-immunoreactive varicosities were observed to abut the soma or proximal dendrites of [Met]enkephalin- and neurotensin-immunoreactive neurons. Nearly 75% of all [Met]enkephalin- and neurotensin-immunoreactive neurons were apposed by serotonin-immunoreactive varicosities in the marginal zone and dorsal gray commissure. In substantia gelatinosa, approximately half of the [Met]enkephalin- and neurotensin-immunoreactive neurons were juxtaposed by serotonin-immunoreactive varicosities. [Met]enkephalin-immunoreactive neurons also were bordered by serotonin-immunoreactive varicosities in the nucleus proprius (65%) and sacral parasympathetic nucleus (75%). The results of this study suggest that the descending serotonergic system mediates nociception via probable contacts with intrinsic enkephalin and neurotensin spinal systems. The mode of action of spinal serotonin on enkephalin and neurotensin neurons may be through "volume" transmission vs synaptic or "wiring" transmission.

Differential expression of alternative splice variants of beta-arrestin-1 and -2 in rat central nervous system and peripheral tissues

Members of arrestin/beta-arrestin protein family are thought to participate in agonist-mediated desensitization of G-protein-coupled receptors, including rhodopsin and beta2-adrenergic receptor. Unlike in human and cow, splice variants of this protein family in rat have not been studied extensively, and there has been no report on their existence at protein level. Hence, a previous report by others on the localization of both beta-arrestin-1 and -2 in a wide range of innervated rat tissues could imply their broad receptor specificity. In this report we show the presence of two alternatively spliced forms of beta-arrestin-1 in several rat tissues using both reverse transcription-polymerase chain reaction and Western immunoblot. Splicing of beta-arrestin-1 pre-mRNA appears to be subject to differential regulation between the rat CNS and peripheral tissues. In contrast, we detected no splice variants of beta-arrestin-2 in rat. A comparison of the genomic DNA sequences of bovine and rat beta-arrestin-2, where the splicing of bovine beta-arrestin-2 mRNA has been reported, revealed a high degree of homology in their organization of exons and introns as well as certain differences that might be responsible for the different processing of beta-arrestin-2 mRNA in the two species. Our two-dimensional isoelectric focusing gels using rat spinal cord and heart tissues demonstrate isoelectric heterogeneity of rat beta-arrestin-1, suggesting that beta-arrestin-1 is subject to post-translational modification unlike beta-arrestin-2.

Athletic participation and sexual behavior in adolescents: the different worlds of boys and girls

Using multivariate analysis of covariance to test hypotheses about the effects of sports and sexual behavior on a sample of 611 Western New York adolescents, this study concludes that athletic participation and gender interact to influence adolescent sexual outcomes. Female athletes report significantly lower rates of sexual activity than female nonathletes; male athletes report slightly (though not significantly) higher rates than male nonathletes. The gender-specific effect of sports on sexual behavior remains, net of the impacts of race, age, socioeconomic status, quality of family relations, and participation in other extracurricular activities. This paper introduces cultural resource theory to explain how athletic participation influences both traditional cultural scripts and exchange resources, which, in turn, condition the sexual bargaining process and its outcomes for adolescents.