On the Respective Roles of Nitric Oxide and Carbon Monoxide in Long-Term Potentiation in the Hippocampus

Perfusion of hippocampal slices with an inhibitor of nitric oxide (NO) synthase-blocked induction of long-term potentiation (LTP) produced by a one-train tetanus and significantly reduced LTP by a two-train tetanus, but only slightly reduced LTP by a four-train tetanus. Inhibitors of heme oxygenase, the synthetic enzyme for carbon monoxide (CO), significantly reduced LTP by either a two-train or four-train tetanus. These results suggest that NO and CO are both involved in LTP but may play somewhat different roles. One possibility is that NO serves a phasic, signaling role, whereas CO provides tonic, background stimulation. Another possibility is that NO and CO are phasically activated under somewhat different circumstances, perhaps involving different receptors and second messengers. Because NO is known to be activated by stimulation of NMDA receptors during tetanus, we investigated the possibility that CO might be activated by stimulation of metabotropic glutamate receptors (mGluRs). Consistent with this idea, long-lasting potentiation by the mGluR agonist tACPD was blocked by inhibitors of heme oxygenase but not NO synthase. Potentiation by tACPD was also blocked by inhibitors of soluble guanylyl cyclase (a target of both NO and CO) or cGMP-dependent protein kinase, and guanylyl cyclase was activated by tACPD in hippocampal slices. However, biochemical assays indicate that whereas heme oxygenase is constitutively active in hippocampus, it does not appear to be stimulated by either tetanus or tACPD. These results are most consistent with the possibility that constitutive (tonic) rather than stimulated (phasic) heme oxygenase activity is necessary for potentiation by tetanus or tACPD, and suggest that mGluR activation stimulates guanylyl cyclase phasically through some other pathway.     

Women, AIDS, and Theatre: Representations and Resistances

The plays written about AIDS in the past dozen years form a radical canon establishing gay men as the locus for public attention. These plays have been all but silent in their representation of women with AIDS. This article examines the marginalized women in early plays such as The Normal Heart and As Is, and the women more central to later plays such as The Baltimore Waltz, Before It Hits Home, and Patient A. It foregrounds some of the most problematic issues surrounding the AIDS virus: the perception of women as vectors of disease for men and unborn children, the insistent representation of women as mothers and caregivers, and the denial of patterns of abuse, sexual exploitation, and poverty which contribute to the marginalization of woman and people of color.     

Billing and Record-Keeping for Familial Cancer Risk Counseling: A National Survey

We surveyed 111 genetic counselors providing cancer risk counseling (CRC) in order to document their billing and record-keeping practices. Of the 75 respondents, billing was generally done under the supervising physician with a wide variation in charges. Follow-up telephone interviews with 28 counselors who charge patients revealed that billing was usually done using the CPT codes for consultations, and the ICD-9 diagnostic codes for cancer (if applicable), a medical complaint, or a family history of cancer code. Most counselors exclude some clinical information from the patient's medical record. In consultation notes, 81% of counselors document a discussion of genetic testing, but only 37% document the patient's actual testing decision, and only 19% document test results. In anticipation of increased referrals for CRC, data are needed on the components of a CRC visit, the amount of time required to provide CRC, patient outcomes measures, and charges and reimbursement. The feasibility and advisability of keeping results separate from the patient's medical record also needs to be addressed.     

The Black-Sheep Effect: How Positive and Negative Advertisements Affect Voters' Perceptions of the Sponsor of the Advertisement1

Participants read a positive or negative (mock) political advertisement that was sponsored by either an in-group (subject and sponsor were members of the same political party) or an out-group (subject and sponsor were members of different political parties) member. The results found support for a black-sheep effect. An in-group sponsor of a positive advertisement was evaluated more positively than any out-group member, regardless of advertisement type, or an in-group member who sponsored a negative advertisement. However, an in-group sponsor of a negative advertisement was evaluated more negatively than either an in-group sponsor of a positive advertisement. or an out-group sponsor. regardless of advertisement type. The results are discussed in terms of social identity theory.     

Evidence for the persistence of visual guidance information

An earlier study from our laboratory provided initial support for the hypothesis that information facilitating visual guidance persists in the absence of retinal stimulation. The present study supports and extends this hypothesis with three experiments in which visually occluded subjects positioned a point of light at the location of a previously viewed target and also walked in the direction of a previously viewed path. In both tasks, performance was possible following occlusion, and in all cases, performance slowly and significantly decreased with longer durations of occlusion. This decay in performance was gradual and had a “half-life” of greater than 15 sec. Absolute performance was correlated across tasks. The effect of occlusion on absolute error in the localization performance was relatively stable within individuals over a 3-week period. The biological utility of guidance information persistence is discussed along with implications for space constancy, illusions of motion, and problems of disorientation.     

Transcultural hospital pastoral care

Transcultural hospital pastoral care's subjects, the immigrant and the refugee, are described. Differences and similarities are noted. Three difficulties—culture shock, prejudice, and ethnocentrism—are followed by principles of transcultural hospital pastoral care, the significance of hospitalization, and a case history.The Rev. David G. Hawkins, B.A., S.T.M., D. Rel., R.S.W., St. George's Anglican Church in Vancouver, is a chaplain at Vancouver General Hospital.     

Decision making under time pressure: An independent test of sequential sampling models

Choice probability and choice response time data from a risk-taking decision-making task were compared with predictions made by a sequential sampling model. The behavioral data, consistent with the model, showed that participants were less likely to take an action as risk levels increased, and that time pressure did not have a uniform effect on choice probability. Under time pressure, participants were more conservative at the lower risk levels but were more prone to take risks at the higher levels of risk. This crossover interaction reflected a reduction of the threshold within a single decision strategy rather than a switching of decision strategies. Response time data, as predicted by the model, showed that participants took more time to make decisions at the moderate risk levels and that time pressure reduced response time across all risk levels, but particularly at the those risk levels that took longer time with no pressure. Finally, response time data were used to rule out the hypothesis that time pressure effects could be explained by a fast-guess strategy.     

On the Respective Roles of Nitric Oxide and Carbon Monoxide in Long-Term Potentiation in the Hippocampus

Perfusion of hippocampal slices with an inhibitor nitric oxide (NO) synthase blocked induction of long-term potentiation (LTP) produced by a one-train tetanus and significantly reduced LTP by a two-train tetanus, but only slightly reduced LTP by a four-train tetanus. Inhibitors of heme oxygenase, the synthetic enzyme for carbon monoxide (CO), significantly reduced LTP by either a two-train or four-train tetanus. These results suggest that NO and CO are both involved in LTP but may play somewhat different roles. One possibility is that NO serves a phasic, signaling role, whereas CO provides tonic, background stimulation. Another possibility is that NO and CO are phasically activated under somewhat different circumstances, perhaps involving different receptors and second messengers. Because NO is known to be activated by stimulation of NMDA receptors during tetanus, we investigated the possibility that CO might be activated by stimulation of metabotropic glutamate receptors (mGluRs). Consistent with this idea, long-lasting potentiation by the mGluR agonist tACPD was blocked by inhibitors of heme oxygenase but not NO synthase. Potentiation by tACPD was also blocked by inhibitors of soluble guanylyl cyclase (a target of both NO and CO) or cGMP-dependent protein kinase, and guanylyl cyclase was activated by tACPD in hippocampal slices. However, biochemical assays indicate that whereas heme oxygenase is constitutively active in hippocampus, it does not appear to be stimulated by either tetanus or tACPD. These results are most consistent with the possibility that constitutive (tonic) rather than stimulated (phasic) heme oxygenase activity is necessary for potentiation by tetanus or tACPD, and suggest that mGluR activation stimulates guanylyl cyclase phasically through some other pathway.     

Landmark Discrimination Learning in the Dog

Allocentric spatial memory was studied in dogs of varying ages and sources using a landmark discrimination task. The primary goal of this study was to develop a protocol to test landmark discrimination learning in the dog. Using a modified version of a landmark test developed for use in monkeys, we successfully trained dogs to make a spatial discrimination on the basis of the position of a visual landmark relative to two identical discriminanda. Task performance decreased, however, as the distance between the landmark and the “discriminandum” was increased. A subgroup of these dogs was also tested on a delayed nonmatching to position spatial memory task (DNMP), which relies on egocentric spatial cues. These findings suggest that dogs can acquire both allocentric and egocentric spatial tasks. These data provide a useful tool for evaluating the ability of canines to use allocentric cues in spatial learning.