Learning in Parkinson's disease: eyeblink conditioning, declarative learning, and procedural learning

OBJECTIVE

To assess the degree of learning ability in Parkinson's disease.

METHODS

Three different learning tasks: eyeblink classical conditioning with delay and trace paradigms, the California verbal learning test (CVLT), and a serial reaction time task (SRTT) were studied in patients with Parkinson's disease and normal (control) subjects.

RESULTS

In the eyeblink conditioning tasks, both patients and normal subjects showed significant learning effects without between group differences. In the CVLT, patients remembered significantly fewer words than normal subjects in both short term and long term cued recall tasks. In the SRTT, normal subjects had significantly reduced response time and error rates across blocks of repeated sequence trials, whereas patients had significantly reduced error, but not response time rates.

CONCLUSION

Impairment of nigrostriatal pathways selectively affects performance in complex learning tasks that are competitive and require alertness such as the SRTT, but not in simple learning procedures such as eyeblink conditioning.

Concept formation and concept shifting in frontal lesion and Parkinson's disease patients assessed with the California Card Sorting Test

Concept formation and shifting abilities of 17 frontal lesion (FL) and 8 Parkinson's disease (PD) patients were assessed with the California Card Sorting Test. FL patients demonstrated a significantly greater number of perseverative responses and deficits in strategy planning, strategy initiation, and concept formation and did not benefit from abstract cues in comparison with their matched normal control (NC) participants. PD patients also demonstrated an increased number of perseverative responses under selected conditions in comparison with their matched NCs, but their ability to explain their sorts, to extract and express the sorting principles, and to sort with the help of abstract and concrete cues depended on their general cognitive status.

Risk factors for sleep-disordered breathing in children. Associations with obesity, race, and respiratory problems

This study examined risk factors for sleep-disordered breathing (SDB) in children and adolescents; specifically, quantifying risk associated with obesity, race, and upper and lower respiratory problems. Subjects were participants in a genetic-epidemiologic study of SDB and included 399 children and adolescents 2 to 18 yr of age, recruited as members of families with a member (a proband) with known sleep apnea (31 index families) or as members of neighborhood control families (30 families). SDB was assessed with home overnight multichannel monitoring and SDB was defined based on an apneahypopnea index >/= 10 (moderately affected) or < 5 (unaffected). SDB of moderate level was significantly associated with obesity (odds ratio, 4.59; 95% confidence interval [CI], 1.58 to 13.33) and African-American race (odds ratio, 3.49; 95% CI, 1.56 to 8.32) but not with sex or age. After adjusting for obesity, proband sampling, race and familial clustering, sinus problems and persistent wheeze each independently (of the other) predicted SDB. These data suggest the importance of upper and lower respiratory problems and obesity as risk factors for SDB in children and adolescents. Increased risk in African Americans appears to be independent of the effects of obesity or respiratory problems.

Discourse deficits following right hemisphere damage in deaf signers

Previous findings have demonstrated that hemispheric organization in deaf users of American Sign Language (ASL) parallels that of the hearing population, with the left hemisphere showing dominance for grammatical linguistic functions and the right hemisphere showing specialization for non-linguistic spatial functions. The present study addresses two further questions: first, do extra-grammatical discourse functions in deaf signers show the same right-hemisphere dominance observed for discourse functions in hearing subjects; and second, do discourse functions in ASL that employ spatial relations depend upon more general intact spatial cognitive abilities? We report findings from two right-hemisphere damaged deaf signers, both of whom show disruption of discourse functions in absence of any disruption of grammatical functions. The exact nature of the disruption differs for the two subjects, however. Subject AR shows difficulty in maintaining topical coherence, while SJ shows difficulty in employing spatial discourse devices. Further, the two subjects are equally impaired on non-linguistic spatial tasks, indicating that spared spatial discourse functions can occur even when more general spatial cognition is disrupted. We conclude that, as in the hearing population, discourse functions involve the right hemisphere; that distinct discourse functions can be dissociated from one another in ASL; and that brain organization for linguistic spatial devices is driven by its functional role in language processing, rather than by its surface, spatial characteristics.

Concept formation and concept shifting in frontal lesion and Parkinson's disease patients assessed with the California Card Sorting Test

Concept formation and shifting abilities of 17 frontal lesion (FL) and 8 Parkinson's disease (PD) patients were assessed with the California Card Sorting Test. FL patients demonstrated a significantly greater number of perseverative responses and deficits in strategy planning, strategy initiation, and concept formation and did not benefit from abstract cues in comparison with their matched normal control (NC) participants. PD patients also demonstrated an increased number of perseverative responses under selected conditions in comparison with their matched NCs, but their ability to explain their sorts, to extract and express the sorting principles, and to sort with the help of abstract and concrete cues depended on their general cognitive status.

Characterization of recombinant human cathepsin B expressed at high levels in baculovirus

The lysosomal cysteine protease cathepsin B has been studied intensely for many years because of its unique characteristics and its potential involvement in disease states. A reproducible, high yield expression system for active recombinant protein is key to biochemical and biophysical studies as well as rational drug design. Although several microbial and mammalian expression systems for recombinant human cathepsin B have been described, these have been limited by low or variable yields. Further, in some of these systems hyper-glycosylation of the enzyme near the active site affects its activity. We describe a baculovirus expression system and purification scheme that solve all of these problems. Yields of active, protected enzyme were reproducibly in excess of 25 mg/L. Since this protein was not hyper-glycosylated, it had greater activity than cathepsin B produced in yeast systems as indicated by a threefold increase in Kcat. In addition, the biophysical properties of the baculovirus-expressed cathepsin B, as measured by dynamic light scattering, were more amenable to crystallographic study since the data indicated proteins of more uniform size. Therefore, this system for the production of recombinant human cathepsin B constitutes a major improvement in both quantity and quality over those previously reported. Further, we demonstrate that the manner of expression and purification of this enzyme has profound effects on its kinetic and physical parameters.

The effect of intrathecal and epidural narcotic analgesia on the length of labor

A number of studies have shown conflicting results on the effect of epidural (EPI) analgesia on the length of labor. Combined spinal-epidural (CSE) and intrathecal analgesia (ITA) techniques have been used to provide pain relief for parturients, but currently there are few studies comparing EPI, CSE, and ITA techniques and their effect on the length of labor. Intrathecal opioids provide immediate pain relief for the parturient without autonomic, sensory, or motor blockade. The purpose of this retrospective study is to identify the effects of ITA on the length of labor compared with other regional anesthesia techniques. A total of 213 uncomplicated obstetric charts were reviewed in a 70-bed Air Force hospital that provided EPI, CSE, and ITA for obstetrical patients. The study consisted of the following four groups: (1) CSE (n = 76), (2) EPI(n = 41), (3) ITA (n = 49), and (4) no regional analgesia (NR) (n = 47). The results showed that the length of first-stage labor was statistically significantly less for those who received ITA compared with those who received CSE, EPI, and NR (P < .001). Second-stage labor was statistically significantly shorter for the NR group compared with the CSE and EPI groups (P < .01). No statistically significant difference was found between the length of second stage for ITA and NR groups. ITA analgesia shortened the first stage significantly in both primipara and multipara patients (P < .01). These results imply that the use of intrathecal opioids in the obstetrical patient does not prolong labor and seems to shorten the first stage of labor in both the primipara and multipara patients.

Regulation of the extracellular ligand binding activity of integrins

Integrins are a large heterodimeric family of cell surface adhesion receptors that bind extracellular matrix and cell surface ligands. The extracellular ligand binding activity of integrins is a dynamic and highly regulated event involving the induction of conformational changes within the integrin structure. The adhesive properties of integrins can be controlled by altering the activation state of the integrin, either through conformational change or receptor clustering, using mechanisms that are regulated by intracellular proteins. In this review, we will discuss what is currently known about integrin structure and the ligand binding sites present within the receptor. In addition, the mechanisms by which the ligand binding event is regulated through conformational change will be addressed, and the potential role of intracellular cytoplasmic proteins will be discussed.

Manual versus mechanical compression for femoral artery hemostasis after cardiac catheterization

BACKGROUND: Most cardiac catheterizations are performed via femoral artery access. Reported rates of both peripheral vascular complications and success rates for the use of manual and mechanical compression techniques to achieve femoral artery hemostasis after cardiac catheterization vary. OBJECTIVE: To determine is use of a mechanical clamp is as effective as standard manual pressure for femoral artery hemostasis after cardiac catheterization. METHODS: Subjects consisted of 720 patients from 2 community hospitals who had elective diagnostic cardiac catheterization via the femoral artery. The control group (n=343) received manual compression for hemostasis; the study group (n=377) received mechanical compression. Standard protocols were used for the 2 compression techniques. Pressure was applied for a minimum of 10 minutes for 5F and 6F sheaths and catheters and for a minimum of 15 minutes for 7F and 8F sheaths and catheters. Prospective data were collected and analyzed for each patients, including sheath or catheter size, blood pressure, height, weight, age, time from administration of local anesthetic to successful cannulation of the femoral artery, anticoagulation status, total compression time, physician performing the catheterization procedure, nurse or technician who obtained hemostasis, and complications. In follow-up, patients were asked site-specific and functional status questions 1 to 2 days after the catheterization procedure and again 3 days after the catheterization procedure. RESULTS: Data were analyzed by using frequency distributions, measures of central tendency, and measures of variability. Only 1 difference between the 2 groups was significant: manual compression time was 14.93 +/- minutes, whereas mechanical compression time was 17.13 +/- minutes. CONCLUSION: Mechanical compression is as effective as manual compression for femoral artery hemostasis after cardiac catheterization.

Normal postexercise facilitation and depression of motor evoked potentials in postpolio patients

We studied the effects of exercise on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation in healthy subjects and postpolio patients. Subjects performed repeated sets of isometric exercise until the muscle fatigued. In both groups, the mean MEP amplitude immediately after each exercise set was approximately twice that of the baseline amplitude, indicating similar postexercise facilitation, and after fatigue was approximately half that of the baseline amplitude, indicating similar postexercise depression. We conclude that the intracortical component of central fatigue is normal in postpolio patients.

Manual versus mechanical compression for femoral artery hemostasis after cardiac catheterization

BACKGROUND

Most cardiac catheterizations are performed via femoral artery access. Reported rates of both peripheral vascular complications and success rates for the use of manual and mechanical compression techniques to achieve femoral artery hemostasis after cardiac catheterization vary.

OBJECTIVE

To determine is use of a mechanical clamp is as effective as standard manual pressure for femoral artery hemostasis after cardiac catheterization.

METHODS

Subjects consisted of 720 patients from 2 community hospitals who had elective diagnostic cardiac catheterization via the femoral artery. The control group (n=343) received manual compression for hemostasis; the study group (n=377) received mechanical compression. Standard protocols were used for the 2 compression techniques. Pressure was applied for a minimum of 10 minutes for 5F and 6F sheaths and catheters and for a minimum of 15 minutes for 7F and 8F sheaths and catheters. Prospective data were collected and analyzed for each patients, including sheath or catheter size, blood pressure, height, weight, age, time from administration of local anesthetic to successful cannulation of the femoral artery, anticoagulation status, total compression time, physician performing the catheterization procedure, nurse or technician who obtained hemostasis, and complications. In follow-up, patients were asked site-specific and functional status questions 1 to 2 days after the catheterization procedure and again 3 days after the catheterization procedure.

RESULTS

Data were analyzed by using frequency distributions, measures of central tendency, and measures of variability. Only 1 difference between the 2 groups was significant: manual compression time was 14.93 +/- minutes, whereas mechanical compression time was 17.13 +/- minutes.

CONCLUSION

Mechanical compression is as effective as manual compression for femoral artery hemostasis after cardiac catheterization.

Schizophrenia Risk and Handedness: A Mixed Picture

Numerous previous studies have reported on handedness differences among schizophrenics, as well as in normal subjects who are high in ''schizotypal'' traits, and hence putatively at risk for schizophrenia. Results have varied, but there is evidence of a shift away from dextrality, especially consistent among schizotypal individuals. Using both a conventional three-category and Annett's seven-category classification of handedness, we re-examined the question in 681 general population subjects assessed for schizotypy. The three-category analysis confirmed previous findings of increased schizotypy in mixed-handers. However, the more fine-grained analysis showed that, although mild degrees of mixed handedness were indeed associated with increased schizotypy, this trend was reversed in the most mixed-handed subjects whose schizotypy scores did not differ significantly from right-handers. Independently of our work, this subgroup of mixed-handers are also reported to show superior intellectual function, especially on some spatial tasks. We concluded that previous studies of schizophrenia and schizotypy have failed to distinguish different reasons for shifts from dextrality. It is argued that the latter's association with schizophrenia might come about through exogenous, neurodevelopmental, influences, whereas some-possibly genetically basedforms of mixed handedness could reflect a variety of cerebral organisation that protects against, rather than enhances, the risk for mental disorder.

Analysis of ligand-induced and ligand-attenuated epitopes on the leukocyte integrin alpha4beta1: VCAM-1, mucosal addressin cell adhesion molecule-1, and fibronectin induce distinct conformational changes

The leukocyte integrin alpha4beta1 is a receptor for both cell surface ligands (VCAM-1 and mucosal addressin cell adhesion molecule-1 (MAdCAM-1)) and extracellular matrix components (fibronectin). Through regulated interactions with these molecules, alpha4beta1 mediates leukocyte migration from the vasculature at sites of inflammation. Regulation of integrin activity plays a key role in controlling leukocyte-adhesive events and appears to be partly determined by changes in integrin conformation. Several mAbs that recognize ligand-induced binding site epitopes on integrins have been characterized, and a subset of these mAbs are capable of stimulating integrin-ligand binding. Conversely, some mAbs recognize epitopes that are attenuated by ligand engagement and allosterically inhibit ligand binding. To gain insight into ligand-specific effects on integrin conformation, we have examined the ability of different ligands to modulate the binding of four distinct classes (A, B1, B2, and C) of anti-alpha4 Abs to alpha4beta1. VCAM-1 attenuated B (antifunctional) class epitopes via an allosteric mechanism and also allosterically inhibited the binding of the function-blocking anti-beta1 mAb 13. Additional alpha4beta1 ligands (fibronectin fragments, MAdCAM-1, and the CS1 peptide) also inhibited mAb 13-integrin binding; however, the epitopes of the class B anti-alpha4 mAbs were attenuated by the fibronectin fragments, but not by MAdCAM-1 or the CS1 peptide. Of the two anti-alpha4 class A mAbs examined, one recognized an epitope that was induced uniquely by VCAM-1. Taken together, these data suggest that overlapping but distinct binding mechanisms exist for different alpha4beta1 ligands and that distinct conformational changes are induced upon integrin engagement by different ligands.

A population-based study of abdominal wall defects in South Australia and Western Australia

The purpose of this study was to determine the prevalence, clinical characteristics, prenatal diagnosis and occurrence of other birth defects with abdominal wall defects in births and terminations of pregnancy in South Australia (SA) and Western Australia (WA) over the period 1980-90. Cases of gastroschisis, exomphalos, bladder exstrophy, cloacal exstrophy and body stalk anomaly were ascertained from the WA Birth Defects Registry (1980-90) and the SA Birth Defects Register (1986-90). The registers are comparable population-based data collections with information on livebirths and stillbirths of at least 400 g birthweight or 20 weeks' gestation, and terminations of pregnancy for fetal abnormality. The prevalence of gastroschisis was 1.65/10,000 births (59 cases) and of exomphalos 2.90/10,000 births (104 cases). There was no significant difference in prevalence of exomphalos or gastroschisis between SA and WA for the years 1986-90. However, if data from WA for the years 1980-85 were included, SA had a significantly higher prevalence of exomphalos (prevalence ratio 1.71, confidence interval [CI] 1.16-2.55), although not of gastroschisis (prevalence ratio 1.35, CI 0.79-2.32). Exomphalos was significantly more common in mothers < 20 years (odds ratio [OR] 2.45, CI 1.22-4.86) and in mothers of 40 years or older (OR 5.65, CI 1.69-16.77). Gastroschisis was more common in younger mothers (OR 8.76, CI 4.02-19.32). Both exomphalos and gastroschisis were associated with low birthweight, prematurity, intrauterine growth retardation and caesarean section. The reason for the higher prevalence of exomphalos in SA than WA was not clear, but may be related to differences in prenatal diagnosis. The association between maternal age < 20 years and exomphalos raises the possibility of common factors in the aetiology of gastroschisis and exomphalos.

An oligo-screening strategy to fill gaps found during shotgun sequencing projects

During the course of projects to sequence human and nematode cosmids we encountered great difficulties generating contiguous sequence in regions with repetitive DNA (Alu repeats in humans and tandem or inverted repeats in the nematode). We have developed a simple and efficient strategy to fill gaps. By screening M13, plasmid or phagemid libraries with oligonucleotides flanking the gap, clones are identified that contiguate the cosmid sequence. Our method has been integrated into the GAP4 sequence assembly program. The strategy reduces both time and costs in large scale sequencing projects.

Characters contributing to high yield in Currawong, an Australian winter wheat

This study investigated characters that contribute to high grain yield in the recently released Australian winter wheat, cv. Currawong. Currawong was released as a feed grade wheat for south-central New South Wales, with a 10% yield advantage over the highest yielding milling wheat with winter habit, Rosella. When expressed as a percentage of the grain yield of Rosella, Currawong was found to perform best at sites with low soil pH and high grain yield. These sites corresponded to the wetter eastern margin of the wheatbelt in south-central New South Wales. While part of the yield advantage of Currawong is due to its tolerance of soil acidity, there remains an ability to yield particularly well in environments conducive to high yield. In yield component studies that were conducted over 2 seasons at Temora, the yield advantage of Currawong appeared to be associated with its grainfilling characters. Currawong had a more rapid rate of grainfill, and/or a longer duration of grainfilling than other high-yielding winter wheats, leading to significantly heavier grain. From a plant breeding perspective, the high yield of Currawong is significant for demonstrating rapid genetic gain for yield in Australian winter wheats. The yield of Currawong also demonstrates the possibility of combining high grain yield with the Sr26 stem rust resistance. Characters that confer high yield in Currawong may be of limited benefit in environments where drought stress limits the duration of grainfilling in wheat.

What nurses should know about natural family planning

Two common natural family planning (NFP) methods are the ovulation method based on characteristics of cervical mucus and the symptothermal method based on changes in cervical mucus, basal body temperature, and the cervix. Both methods are effective when used correctly. Nurses should understand the principles of NFP and introduce these methods in discussions of family planning options. Interested clients should be referred to a certified NFP instructor for education and supervision.

The effect of five proofreading conditions on the spelling performance of college students with learning disabilities

This study investigated the effect of five proofreading conditions on the spelling performance of 12 college students with learning disabilities on a composition activity. The proofreading conditions investigated were handwriting with no additional assistance, handwriting with a conventional print dictionary, handwriting with a handheld spelling checker, word processing with no additional assistance, and word processing with an integrated spelling checker. A repeated measures ANOVA was used to analyze the results, with proofreading condition used as a within-participants factor. Except for handwriting alone, all of the techniques resulted in significant reductions in the number of spelling errors in the students' written work; however, none of the techniques enabled the students to produce compositions with a mean level of spelling accuracy comparable to that of their nondisabled peers.