Dissociating the Impact of Memorability on Electrophysiological Correlates of Memory Encoding Success.

Despite its unlimited capacity, not all visual information we encounter is encoded into visual long-term memory. Traditionally, variability in encoding success has been ascribed to variability in the types and efficacy of an individual's cognitive processes during encoding. Accordingly, past studies have identified several neural correlates of variability in encoding success, namely, frontal positivity, occipital alpha amplitude, and frontal theta amplitude, by contrasting the electrophysiological signals recorded during successful and failed encoding processes (i.e., subsequent memory). However, recent research demonstrated individuals remember and forget consistent sets of stimuli, thereby elucidating stimulus-intrinsic factors (i.e., memorability) that determine the ease of memory encoding independent of individual-specific variability in encoding processes. The existence of memorability raises the possibility that canonical EEG correlates of subsequent memory may reflect variability in stimulus-intrinsic factors rather than individual-specific encoding processes. To test this, we recorded the EEG correlates of subsequent memory while participants encoded 600 images of real-world objects and assessed the unique contribution of individual-specific and stimulus-intrinsic factors on each EEG correlate. Here, we found that frontal theta amplitude and occipital alpha amplitude were only influenced by individual-specific encoding success, whereas frontal positivity was influenced by stimulus-intrinsic and individual-specific encoding success. Overall, our results offer novel interpretations of canonical EEG correlates of subsequent memory by demonstrating a dissociable impact of stimulus-intrinsic and individual-specific factors of memory encoding success.

Cdh13 and AdipoQ gene knockout alter instrumental and Pavlovian drug conditioning.

Genome-wide association studies in humans have suggested that variants of the cadherin-13 (CDH13) gene are associated with substance use disorder, subjective response to amphetamine, and attention deficit hyperactivity disorder. To examine the role of the Cdh13 and its peptide ligand adiponectin (AdipoQ) in addiction-related behaviors, we assessed Cdh13 knockout (KO) rats and AdipoQ KO mice using intravenous cocaine self-administration and conditioned place preference (CPP) paradigms. During intravenous cocaine self-administration, male Cdh13 heterozygous (+/-) and KO (-/-) rats showed increased cue-induced reinstatement compared with wild-type (WT) rats when presented with a cocaine-paired stimulus, whereas female Cdh13 rats showed no differences across genotype. Cdh13 -/- rats showed higher responding for a saccharin reinforcer and learned the choice reaction time (RT) task more slowly than WTs. However, we found no differences between Cdh13 -/- and +/+ rats in responding for sensory reinforcement, number of premature responses in the RT task, tendency to approach a Pavlovian food cue, CPP and locomotor activation to cocaine (10 or 20 mg/kg). In AdipoQ -/- mice, there was a significant increase in CPP to methamphetamine (1 mg/kg) but not to a range of d-amphetamine doses (0.5, 1, 2 and 4 mg/kg). Taken together, these data suggest that Cdh13 and AdipoQ regulate sensitivity to psychomotor stimulants and palatable rewards without producing major changes in other behaviors. In humans, these two genes may regulate sensitivity to natural and drug rewards, thus influencing susceptibility to the conditioned drug effects and relapse.

Live birth of a bear cub following nonsurgical embryo collection.

In the near future, 6 of 8 bear species will face extinction mainly because of loss of their natural habitat. This loss of habitat will ultimately require some of these bears to be maintained in zoos and wildlife preserves in the hope of conserving genetic diversity. If the giant panda is representative of other bear species, reproductive performance will be inhibited in such an environment. In this study, we used the nonendangered American black bear (Ursus americanus) as the model for developing appropriate embryo transfer procedures. The donor bear mated numerous times between late May and early June. In late July we anesthetized her and used a series of telescoping sheaths to gain access to the uterus Then we passed a catheter through the largest sheath, inflated the balloon, and, using a 20-mL syringe, repeatedly infused into and then aspirated from the uterus PBS + BSA. We emptied the syringe into Petri dishes and observed 2 embryos. We rinsed the embryos, placed them in human tubal fluid + HSA + HEPES and then held them at 35 degrees C for 5 h. The recipient mated during mid-June; in late July we anesthetized her and, with the aid of laparoscopy, transferred an embryo into the cranial portion of the uterine horn ipsilateral to the ovary containing a CL. The recipient delivered 2 cubs in January. Necropsy results indicated that the neonates lived for 6 to 8 wk before succumbing to flooding in the den. The DNA from hair samples belonging to the neonates indicated that the male cub belonged to the donor, the female cub to the recipient. The delayed implantation mechanism in bears probably allowed for the successful development of the embryo in the presence of a substantial asynchrony between the donor and the recipient (13 d). We conclude that embryo transfer is possible in the American black bear and can lead to the birth of live cubs.

Predictors of weaning after 6 weeks of mechanical ventilation.

STUDY OBJECTIVE: To identify variables associated with weaning outcome in long-term ventilator-dependent patients. Using those variables, to construct models to predict weaning success and to test the accuracy of those models. DESIGN: Retrospective medical record review. SETTING: Regional weaning center (RWC). PATIENTS: An initial group of 421 and a subsequent group of 170 consecutive patients referred for attempted weaning after 6 weeks of mechanical ventilation. MEASUREMENTS AND RESULTS: Data obtained on admission to our facility were analyzed for correlation with weaning outcome. In the initial patient group, selected variables which correlated with weaning success were alveolar-arterial oxygen pressure difference (P[A-a]O2), BUN, BUN/creatinine ratio (each with p < or = 0.001), and female gender (p = 0.04). We used these variables in logistic regression models to predict weaning success in this population. We then tested the models in the 170-patient validation group using both standard and receiver operating characteristic (ROC) curve analysis. The ROC analysis indicated 59% accuracy using P(A-a)O2 alone and 68% accuracy using all previously mentioned variables. We used data from all 565 patients with known outcome and omitted BUN/creatinine ratio to fashion a simple scoring system to predict weaning success with 70% accuracy using P(A-a)O2, BUN, and Gender--the A+B+G score. CONCLUSION: In patients suffering prolonged mechanical ventilation, models incorporating simple measurements allowed construction of a score to predict weaning success at our RWC.

Weaning from prolonged mechanical ventilation. The experience at a regional weaning center.

STUDY OBJECTIVE: The aim of this study was to describe the facility, patient population, outcome of treatment, and survival of patients transferred to a regional weaning center (RWC) after prolonged mechanical ventilation in the ICU setting. DESIGN: Retrospective record review. SETTING: Regional weaning center. PATIENTS: Four hundred twenty-one consecutive ventilator dependent patients were transferred from ICU care for attempted weaning over a 36-month period. MEASUREMENT AND RESULTS: Acute catastrophic surgical, traumatic, or septic illness resulted in ventilator dependency with much greater frequency than decompensated COPD. Of the 421 patients, 116 died and 287 survived with outcome known at discharge. Of the 287 who survived, 212 were freed from ventilator support. Patients who weaned were ventilator-dependent for 46.9 +/- 2.9 days before transfer to the RWC. Almost half of those weaned were discharged to their homes. Survival at 6 months and 1 year after discharge was 44 percent and 28 percent respectively, and it was greater for those at home than for those discharged to an extended care facility (ECF). The RWC care was approximately $1,500 per patient day less costly than ICU care, and $208 per patient day less costly than noninvasive respiratory care unit care. CONCLUSIONS: Selected patients who become ventilator dependent for prolonged periods in the ICU may be transferred to an RWC with the expectation of successful weaning in a majority of cases.

Carotid endarterectomy: a ten-year analysis of outcome and cost of treatment.

Between 1978 and 1988, 215 patients with an average age of 67 years, underwent 246 carotid endarterectomies. Two hundred ten (85.4%) patients were symptomatic, and 36 (14.6%) were asymptomatic. Six patients (2.4%) had a postoperative stroke, and all had immediate reoperation. One of these patients died (30 day mortality rate, 0.4% for the series), and two (0.8%) recovered completely, whereas three (1.2%) had a mild permanent neurologic deficit. Two patients (0.8%) had nonfatal myocardial infarction. Mean follow-up of 42.2 months (range, 1 to 126 months) was achieved. At 5 and 8 years actuarial survival rates of 82% and 66% and stroke-free survival rates of 67% and 37% were observed. Actuarial stroke free rates of 90% at 5 and 8 years were noted. By introducing and observing guidelines that required preoperative study of most clearly defined classes of patients before admission for surgical treatment, the average length of stay for carotid endarterectomy was lowered from 9.5 days in the first 5 years of the study to 5.8 days in the second 5 years (p = 0.001). Average hospital charges, expressed in constant dollars, decreased from $3113 in the first 5 years to $2620 in the second 5 years (p = 0.02) despite an 88% inflationary increase in medical consumer price index. This experience shows that the length of hospitalization of patients with carotid endarterectomy can be reduced and the cost of admission lowered without untoward effect on perioperative morbidity and mortality rates.

Topical aminocaproic acid significantly reduces the incidence of secondary hemorrhage in traumatic hyphema in the rabbit model.

Systemically administered aminocaproic acid has been shown to reduce the incidence of secondary hemorrhage after traumatic hyphema. To date, no topical treatment has been shown to be effective in reducing the incidence of rebleeding in a double-masked study. Experimentally induced traumatic hyphemas in the rabbit model were treated with topical placebo gel (4% carboxypolymethylene gel only) or carboxypolymethylene gel with amino-caproic acid (treated group) in a double-masked fashion and were compared with untreated controls (control group). In both the control and placebo groups, there was a 33% rebleed rate. The treated eyes had a 10% rebleed rate that is statistically significant. The topically applied aminocaproic acid gel appears to be well tolerated locally without evidence of systemic toxicity. This study indicates that topical aminocaproic acid may be an effective alternative to systemic treatment to reduce the incidence of secondary hemorrhage in traumatic hyphema.

Transmission of bovine brucellosis from dam to offspring.

Transmission of bovine brucellosis from dam to offspring under natural circumstances was demonstrated in a 2 1/2-year study of an infected cow and her calf. The cow delivered a full-term heifer calf after her first gestation. The calf remained with its dam until 7 months of age, then was placed in isolation until bred. During her first gestation, the second-generation heifer became seropositive for Brucella abortus. She later gave birth to a calf with B abortus infection, as determined by isolation of B abortus biotype 1 from stomach contents, heart blood, lung, and spleen of the calf. The same organism was isolated from the placenta and milk of the dam.

Children's comprehension of grammatical structures in context.

Children from nursery school, kindergarten, and first grade were asked to select pictures which correctly represented the propositional content of six grammatical structures-active, passive, cleft-agent, cleft-patient, prepositional beneficiary, indirect object-presented under three context conditions-appropriate, inappropriate, isolation. In the appropriate-context condition the relationship between the target structure and its prior context sentence followed known discourse regularities about the allocation of given and new information, while in the inappropriate-context condition the relationship between the target structure and prior context violated these discourse regularities. Comprehension of two of the grammatical structures tested--the passive and the cleft-patient--was better under the appropriate-context treatment than under the inappropriate-context treatment, indicating that young children are in fact sensitive to discourse regularities about the allocation of given and new information.

Observations on the life cycle and prevalence of Eimeria leuckarti in horses in Montana.

Of 22 foals from 4 localities in southwestern Montana, 59% were found to be infected with Eimeria leuckarti. Oocysts collected from feces of 4 positive horses were sporulated and subsequently administered to a 5- to 6-month-old foal. The prepatent period was 31 days and the patent period was between 5 and 10 days.

Calf ligated intestinal segment test to detect enterotoxigenic Escherichia coli.

The ligated intestinal segment test in the young calf was utilized to establish the enterotoxigenicity of approximately 600 Escherichia coli isolates obtained from fecal specimens intestinal contents of calves with diarrheal disease. One hundred and fifty isolates were routinely tested in a single calf. There was little problem with false-positive reactions. False-negative reactions normally occurred only if the isolate was tested in the posterior 3 m of the small intestine. The ligated small intestine of the calf was distended by E. coli isolates of bovine, porcine, and human origin. Use of the calf ligated intestinal segment test is recommended to determine the enterotoxigenicity of E. coli isolates of bovine origin.

Nucleoside conformations. XVII. A PMR study of 2'-anhydronucleosides and comparison with X-ray data.

A series of 2'-cyclo-nucleosides (2,2'-O-anhydro-uridine, -N(3)-uridine and cytidine and 8,2'-S-anhydro-guanosine) have been studied by PMR in DMSO and D(2)O. As expected these compounds are quite rigid, but their solution conformation is considerably different from that observed in single crystal x-ray studies. While the pyrimidine cyclonucleosides in the crystal form show a C(4')-endo conformation (pseudorotational phase angle P=212 degrees to 233 degrees ), their solution conformation is C(1')-exo (P=130 degrees to 138 degrees ) and the cyclothioguanosine shows a closely similar one (P=112 degrees ). Exocyclic rotamer distribution is different in the various compounds.

Prevention of experimentally induced enteric colibacillosis in newborn calves.

Severe enteric colibacillosis, characterized by profuse watery diarrhea, dehydration, apathy, hypothermia, and inability to stand, was produced in seven of eight newborn, colostrum-fed calves from nonvaccinated dams after oral challenge of calves with 10(11) viable cells of Escherichia coli strain B44. Twenty-nine of 32 calves from dams vaccinated with various preparations of E. coli strain B44 were protected against severe enteric colibacillosis after oral challenge. Calves were protected if the dams received two subcutaneous vaccinations prior to calving. Calves also were protected if the dams were given a homologous vaccine of live or killed whole cells or a broth culture supernatant vaccine via the subcutaneous and intramammary routes 1 year earlier. Nineteen of the 29 protected calves had a transient diarrhea.