The psychological refractory period effect following callosotomy: uncoupling of lateralized response codes

A callosotomy patient was tested in 2 dual-task experiments requiring successive speeded responses to lateralized stimuli. The patient showed a robust psychological refractory period (PRP) effect. Three aspects of the data indicate that, unlike for the control participants, the PRP effect for the split-brain patient should not be attributed to a response selection bottleneck. First, the patient did not show an increase in reaction time (RT) when the 2 tasks required responses from a common output system compared with when different output systems were used. Second, inconsistent stimulus-response mappings for the 2 tasks increased RTs for the control participants but had minimal effect on the performance of the split-brain patient. Third, the consistency manipulation was underadditive with stimulus onset asynchrony but was additive or overadditive for the normal participants. These results suggest that the persistent PRP effect following callosotomy should be attributed to a bottleneck associated with response initiation, a strategy adopted to comply with the task demands, or a combination of these factors.

The psychological refractory period effect following callosotomy: uncoupling of lateralized response codes

A callosotomy patient was tested in 2 dual-task experiments requiring successive speeded responses to lateralized stimuli. The patient showed a robust psychological refractory period (PRP) effect. Three aspects of the data indicate that, unlike for the control participants, the PRP effect for the split-brain patient should not be attributed to a response selection bottleneck. First, the patient did not show an increase in reaction time (RT) when the 2 tasks required responses from a common output system compared with when different output systems were used. Second, inconsistent stimulus-response mappings for the 2 tasks increased RTs for the control participants but had minimal effect on the performance of the split-brain patient. Third, the consistency manipulation was underadditive with stimulus onset asynchrony but was additive or overadditive for the normal participants. These results suggest that the persistent PRP effect following callosotomy should be attributed to a bottleneck associated with response initiation, a strategy adopted to comply with the task demands, or a combination of these factors.

Dependence by any other name smells just as sweet: reply to van der Velde and van der Heijden (1997)

The hypothesis that people selectively attend to entire objects predicts that all attributes of an object will be reported either very accurately (if the object was attended) or very inaccurately (if it was unattended). Hence, reports of object attributes should show positive dependence. M. Monheit and J. Johnston (1994) have confirmed this prediction. F. van der Velde and A. H. C. van der Heijden (1997), however, have argued that dependence in the overall data is spurious. They advocate a model that partitions the data into 2 subsets, 1 for perception trials and 1 for guessing trials, each of which separately exhibits independence. Here, the authors argue that this treatment of guessing is misguided because, in effect, guesses are discarded rather than treated as failures of perception. The Monheit and Johnston analysis, on the other hand, is fundamentally sound and demonstrates precisely the kind of dependence predicted by the spatial attention hypothesis.

Perceptual repetition blindness effects

Repetition blindness (RB) may reveal a new limitation on human perceptual processing. Recently, however, researchers have attributed RB to postperceptual processes. The standard rapid serial visual presentation (RSVP) paradigm used in most RB studies is open to such objections. The "single-frame" paradigm introduced by J. C. Johnston and B. L. Hale (1984) allowed investigation of RB with minimal memory demands. Participants made a judgment about whether 1 masked target word was the same or different than a posttarget probe. Confidence ratings permitted use of signal detection methods. In the critical condition for RB, a precue of the posttarget word was provided prior to the target stimulus so that the required judgment amounted to whether the target did or did not repeat the precue word. In control treatments, the precue was an unrelated word or a dummy. Results showed that perceptual sensitivity was significantly reduced in the RB condition relative to baseline control conditions. The data showed that RB can be obtained under conditions in which memory problems are minimal and perceptual sensitivity is assessed independently of biases. RB therefore can be a perceptual phenomenon.

Laparoscopic cholecystectomy in the geriatric population

OBJECTIVE

To assess effectiveness and conversion rates of inpatient laparoscopic cholecystectomy in older people living in the community.

SETTING AND SUBJECTS

All acute care hospitals providing cholecystectomy in a single state. Medicare patients who underwent inpatient cholecystectomy in fiscal year 1994 in Arkansas.

METHODS

A random sample comprising 449 of 2182 geriatric patients who underwent inpatient cholecystectomy in fiscal year 1994, stratified by hospital bed size, had charts reviewed for type of cholecystectomy performed, occurrence of conversion from a laparoscopic to an open cholecystectomy, surgical complications, and need for transfusion.

RESULTS

Eighty-two percent of nonincidental cholecystectomies were initially laparoscopic. Total conversion rate for all inpatient laparoscopic cases was 20%. Forty-two percent of this group suffered acute cholecystitis with male patients exhibiting a higher rate of acute cholecystitis than female patients. Conversion rates for elective cholecystectomy for both sexes was between 13 and 14%. Conversion rate to an open procedures was 28% for patients with acute disease, with male patients again having a higher rate than female patients (40% vs 19%, P < .001). Surgical complications and intraoperative transfusions were rare. Conversion rates did not vary between large and small hospitals or among different age groups within the older population.

CONCLUSIONS

Inpatient laparoscopic cholecystectomy is common in older people both for acute and chronic gallbladder conditions. Conversion rates ranged from 13% for elective cholecystectomy to 28% for acute disease. These rates are higher than published literature, which focuses on younger populations undergoing elective procedures. Audit committees need to be aware of this higher conversion rate in older people when assessing surgical proficiency.

Both codon context and leader length contribute to efficient expression of two overlapping open reading frames of a cucumber necrosis virus bifunctional subgenomic mRNA

The importance of codon context and leader length in the translational regulation of p20 and p21 from the bifunctional 0.9-kb subgenomic mRNA cucumber necrosis virus was investigated. Nucleotide substitutions introduced into the -3 and +4 positions of the p21 AUG codon (where the A of the AUG is +1) verified that purines in these positions are favored and demonstrated the similar contribution of the -3 and +4 positions to the efficiency of initiation codon selection in plants. The effect of nucleotide substitutions in the +5 position, most clearly demonstrated when pyrimidines occupy the -3 and +4 positions, also provided direct insight into the influence of the +5 position in plants. The codon context of the upstream p21 initiation codon affected expression from the downstream p20 AUG codon. In addition, an increase in the length of the subgenomic mRNA leader decreased expression from the downstream p20 initiation site. These latter observations are in accordance with the "Kozak rules" for accession of internal AUG codons by leaky ribosomal scanning and provide the first example of an effect of leader length on the efficiency of translation initiation in a plant (viral) mRNA.

Perceptual repetition blindness effects

Repetition blindness (RB) may reveal a new limitation on human perceptual processing. Recently, however, researchers have attributed RB to postperceptual processes. The standard rapid serial visual presentation (RSVP) paradigm used in most RB studies is open to such objections. The "single-frame" paradigm introduced by J. C. Johnston and B. L. Hale (1984) allowed investigation of RB with minimal memory demands. Participants made a judgment about whether 1 masked target word was the same or different than a posttarget probe. Confidence ratings permitted use of signal detection methods. In the critical condition for RB, a precue of the posttarget word was provided prior to the target stimulus so that the required judgment amounted to whether the target did or did not repeat the precue word. In control treatments, the precue was an unrelated word or a dummy. Results showed that perceptual sensitivity was significantly reduced in the RB condition relative to baseline control conditions. The data showed that RB can be obtained under conditions in which memory problems are minimal and perceptual sensitivity is assessed independently of biases. RB therefore can be a perceptual phenomenon.

Deletion analysis of the promoter for the cucumber necrosis virus 0.9-kb subgenomic RNA

Sequences comprising the core promoter for the cucumber necrosis virus (CNV) 0.9-kb subgenomic RNA have been determined using deletion analysis and site-directed mutagenesis. The deletion studies indicate that the promoter lies within a region located 20 nucleotides upstream and 6 nucleotides downstream and including the subgenomic start site. Sequences further upstream or downstream of the core promoter do not appear to strongly affect promoter activity or viral RNA accumulation. Results of site-directed mutagenesis studies indicate that nucleotides immediately surrounding the subgenomic start site regulate promoter activity. Comparison of sequences within the CNV promoter region with the corresponding region of other tombusviruses shows that the tombusvirus promoter shares a region of near complete identity in 14 of the 26 core promoter nucleotides. Little similarity exists between the CNV 0.9-kb subgenomic RNA promoter and the region surrounding the transcription initiation site for the CNV 2.1-kb subgenomic RNA. Likewise, limited similarity occurs with the 5' region of CNV genomic RNA. Sequences similar to the ICR2-like motifs found in the promoters of several alphavirus-like (supergroup III) plant and animal viruses are not apparent. This study represents the first analysis of a subgenomic promoter from a member of supergroup II of positive-strand RNA viruses.

Mutational analysis of the cucumber necrosis virus coat protein gene

A series of frameshift, deletion, and inversion mutations were made in the coat protein (CP) gene of the icosahedral cucumber necrosis tombusvirus (CNV) to investigate the role of the CP protruding (P) domain in the production of virus particles and, also, to investigate the basis for the accumulation of CP deletion derivatives previously reported in plants inoculated with PD(-), a P-domainless CNV CP mutant. P-domainless coat protein subunit could be detected in extracts of CP mutant-infected plants; however, virus-like particles could not, suggesting that the P domain is essential for tombusvirus particle assembly and/or stability. In addition, each of the P-domain mutants analyzed invariably produced coat protein deletion derivatives in infected plants whereas shell domain mutants rarely produced deletion derivatives. Finally, P-domain inversion and deletion mutants accumulated deletion derivatives very rapidly in comparison to P-domain frameshift mutants. Protoplast studies show that PD(-) RNA inoculum does not undergo further deletion in infected protoplasts, suggesting that PD(-) CP deletion derivatives preferentially accumulate in plants because they have a greater capacity for cell-to-cell movement.

Spatial attention to arrays of multidimensional objects

Encoding briefly displayed arrays of multidimensional objects appears to require selective attention, but this hypothesis is challenged by M. J. Nissen's (1985) finding that properties of an object are reported independently. Selective attention to some objects but not others should produce positive dependence. Theoretical analysis shows that deviations from independence would have been difficult to observe in Nissen's data because of high guessing rates and small sample sizes. Four new experiments showing strong positive dependence in property reports are described. Deviations from independence were highly significant for most Ss. Quantitative modeling shows that selective attention to subsets of objects would produce about the amount of dependence obtained. Rather than challenging attention theories, the amount of dependence in encoding multidimensional objects is consistent with selective attention to either objects or locations.

Spatial attention to arrays of multidimensional objects

Encoding briefly displayed arrays of multidimensional objects appears to require selective attention, but this hypothesis is challenged by M. J. Nissen's (1985) finding that properties of an object are reported independently. Selective attention to some objects but not others should produce positive dependence. Theoretical analysis shows that deviations from independence would have been difficult to observe in Nissen's data because of high guessing rates and small sample sizes. Four new experiments showing strong positive dependence in property reports are described. Deviations from independence were highly significant for most Ss. Quantitative modeling shows that selective attention to subsets of objects would produce about the amount of dependence obtained. Rather than challenging attention theories, the amount of dependence in encoding multidimensional objects is consistent with selective attention to either objects or locations.

Frequency and recognition of angiotensin-converting enzyme inhibitor-associated angioneurotic edema

OBJECTIVE

To evaluate the frequency of association of angiotensin-converting enzyme (ACE) inhibitor therapy with angioneurotic edema and the frequency of correct diagnosis by treating physicians.

DESIGN

Retrospective population-based chart review.

SETTING

Medicare patients identified with 1991 and 1992 MEDPRO data set.

RESULTS

51 patients were identified from the MEDPRO data sets. Twenty-four patients (47%) had ACE inhibitor-associated angioneurotic edema of whom 17 (71% of the subgroup) had the medication stopped. Twenty-nine percent of the affected patients were discharged still taking an ACE inhibitor. Twenty-six patients (51% of the total population) had non-ACE inhibitor-associated angioneurotic edema and one patient had an uncertain history.

CONCLUSION

ACE inhibitor therapy is the number one cause of angioneurotic edema in our hospitalized patient population. Recognition of the association of this drug with the condition was not recognized in 29% of cases and the offending agent was continued upon discharge from the hospital.

Idiopathic eosinophilic esophagitis

A retrospective review was performed of 13 patients with the diagnosis of idiopathic eosinophilic esophagitis (IEE) occurring alone or in conjunction with idiopathic eosinophilic gastroenteritis (IEG) to identify clinical, radiographic, endoscopic, manometric, and therapeutic similarities. All patients presented with esophageal symptoms, predominantly dysphagia. An allergic disorder was present in 10 (77%) patients, and peripheral eosinophilia was present in 12 (92%) patients. Clinical investigation disclosed esophageal strictures in 10 patients, motility disorders in three, ulcerations in two, a cervical web in one, and a mucosal ring in one as the cause of esophageal symptoms. A proximal esophageal stricture was the single most common esophageal abnormality demonstrated. IEE should be included in the differential diagnosis of dysphagia and should be suggested in a patient with an allergic disorder, peripheral eosinophilia, and concurrent abdominal symptoms, especially in conjunction with IEG. Prompt diagnosis is extremely important since treatment with steroids produces rapid clinical remission in most patients.

The role of spatial attention in visual word processing

Subjects made lexical decisions on a target letter string presented above or below fixation. In Experiments 1 and 2, target location was cued 100 ms in advance of target onset. Responses were faster on validly than on invalidly cued trials. In Experiment 3, the target was sometimes accompanied by irrelevant stimuli on the other side of fixation; in such cases, responses were slowed (a spatial filtering effect). Both cuing and filtering effects on response time were additive with effects of word frequency and lexical status (words vs. nonwords). These findings are difficult to reconcile with claims that spatial attention is less involved in processing familiar words than in unfamiliar words and nonwords. The results can be reconciled with a late-selection locus of spatial attention only with difficulty, but are easily explained by early-selection models.

Involuntary covert orienting is contingent on attentional control settings

Four experiments tested a new hypothesis that involuntary attention shifts are contingent on the relationship between the properties of the eliciting event and the properties required for task performance. In a variant of the spatial cuing paradigm, the relation between cue property and the property useful in locating the target was systematically manipulated. In Experiment 1, invalid abrupt-onset precues produced costs for targets characterized by an abrupt onset but not for targets characterized by a discontinuity in color. In Experiment 2, invalid color precues produced greater costs for color targets than for abrupt-onset targets. Experiment 3 provided converging evidence for this pattern. Experiment 4 investigated the boundary conditions and time course for attention shifts elicited by color discontinuities. The results of these experiments suggest that attention capture is contingent on attentional control settings induced by task demands.

Involuntary attentional capture by abrupt onsets

The extent to which brief abrupt-onset visual stimuli involuntarily capture spatial attention was examined in five experiments. The paradigm used was intended to maximize the opportunity and incentive for subjects to ignore abrupt-onset distractor stimuli in nontarget locations. Subjects made a speeded two-choice response to a target letter appearing in one of four boxes. An abrupt-onset visual stimulus, easily discriminable from the target, was flashed briefly prior to the presentation of a target. In separate blocks, the flash stimulus marked the box in which the target would subsequently appear (SAME), a different box (DIFF), fixation (CENTER), or all four boxes (ALL). Prior to each block, subjects were informed of the flash-target relationship. In all five experiments, response time was elevated in the DIFF, CENTER, and ALL conditions. The interference effect was larger for the DIFF condition and persisted for longer flash-target SOAs. These results suggest that, under appropriate conditions, spatial attention can be involuntarily drawn to abrupt-onset events despite the intention of subjects' to ignore them.

The role of spatial attention in visual word processing

Subjects made lexical decisions on a target letter string presented above or below fixation. In Experiments 1 and 2, target location was cued 100 ms in advance of target onset. Responses were faster on validly than on invalidly cued trials. In Experiment 3, the target was sometimes accompanied by irrelevant stimuli on the other side of fixation; in such cases, responses were slowed (a spatial filtering effect). Both cuing and filtering effects on response time were additive with effects of word frequency and lexical status (words vs. nonwords). These findings are difficult to reconcile with claims that spatial attention is less involved in processing familiar words than in unfamiliar words and nonwords. The results can be reconciled with a late-selection locus of spatial attention only with difficulty, but are easily explained by early-selection models.

Infectious transcripts from cloned cucumber necrosis virus cDNA: evidence for a bifunctional subgenomic mRNA

Highly infectious synthetic transcripts from full-length cucumber necrosis virus (CNV) cDNA clones have been prepared. Infections produced by these transcripts, by CNV RNA, and by mutated transcripts are compared. Inoculation with natural CNV RNA resulted in a mild systemic necrosis in Nicotiana clevelandii, whereas inoculation with synthetic CNV transcripts resulted in severe systemic necrosis. An abundant low molecular weight RNA species was associated with CNV RNA infections but was not detected in synthetic transcript infections. Differences in the symptoms and the RNA profiles produced by these two inoculums indicate that our laboratory strain of CNV contains defective interfering RNAs. Studies using mutant synthetic CNV transcripts which contain point substitutions in the AUG codons for two 3' terminal nested open reading frames encoding 21- and 20-kDa proteins are also described. Evidence is presented which suggests that both the 21- and 20-kDa proteins are produced during CNV infection, although only one subgenomic mRNA which can encode both of these proteins can be detected in infected plants. Together, these results indicate that the CNV 21- and 20-kDa proteins are expressed from a bifunctional subgenomic mRNA generated during CNV infection.

Close binding of identity and location in visual feature perception

The binding of identity and location information in disjunctive feature search was studied. Ss searched a heterogeneous display for a color or a form target, and reported both target identity and location. To avoid better than chance guessing of target identity (by choosing the target less likely to have been seen), the difficulty of the two targets was equalized adaptively; a mathematical model was used to quantify residual effects. A spatial layout was used that minimized postperceptual errors in reporting location. Results showed strong binding of identity and location perception. After correction for guessing, no perception of identity without location was found. A weak trend was found for accurate perception of target location without identity. We propose that activated features generate attention-calling "interrupt" signals, specifying only location; attention then retrieves the properties at that location.

Translation of cucumber necrosis virus RNA in vitro

The in vitro translation products directed by cucumber necrosis virus (CNV) RNA were analysed in both rabbit reticulocyte lysate and wheatgerm extract cell-free translation systems. In rabbit reticulocyte lysates, one major protein of approximate Mr 34.6K was produced. In wheatgerm extracts, four proteins of approximate Mr values 41.6K, 34.6K, 24K and 20K were produced. The genomic locations of the CNV in vitro translation products were determined using several experimental approaches including, first, hybrid-arrested translation using negative-sense RNA corresponding to selected regions of the CNV genome, second, in vitro translation of synthetic positive-sense CNV transcripts and third, in vitro translation of CNV virion RNA fractionated according to size. Together these experiments demonstrated that the protein of Mr 34.6K is derived from the 5'-proximal coding region, the 41.6K protein is derived from an internal coding region, and that at least one but probably both the 24K and 20K proteins are derived from the 3'-terminal coding region. In addition, immunoprecipitation of in vitro translation products using anti-CNV polyclonal serum demonstrated that the 41.6K protein is the coat protein. The templates for the expression of CNV cistrons were investigated by in vitro translation of sucrose gradient-fractionated CNV virion RNA as well as in vitro translation of positive-sense synthetic transcripts.