Event-related potentials (ERPs) to hemifield presentations of emotional stimuli: differences between depressed patients and healthy adults in P3 amplitude and asymmetry

Depression may involve dysfunction of right parietotemporal cortex, a region activated during perception of affective stimuli. To further test this hypothesis, event-related brain potentials (ERPs) were measured in a paradigm previously shown to produce ERP asymmetries to affective stimuli over parietal sites in healthy adults. Pictures of patients with dermatological diseases showing disordered or healed facial areas before (negative) or after (neutral) surgical treatment were briefly exposed for 250 ms to either the left or right hemifield. ERPs of 30 unmedicated, unipolar depressed patients and 16 healthy adults, all right-handed, were recorded from 30 electrodes. A principal components analysis extracted factors which closely corresponded to distinctive ERP components previously reported for this task (N1, N2, early P3, late P3, slow wave). Significant effects of emotional content, i.e. enhanced amplitudes to negative than neutral stimuli, were found for early and late P3. Control subjects showed significant hemispheric asymmetries of emotional processing for late P3 (peak latency 460 ms), with the largest emotional content effects over the right parietal region. In striking contrast to control subjects, depressed patients did not show an increase in late P3 for negative compared to neutral stimuli over either hemisphere and had smaller late P3 amplitude than control subjects. Patients did, however, show larger early P3 (peak latency 330 ms) to negative than neutral stimuli. Results suggest intact early discrimination but abnormal late appraisal of affective content in depression, which may arise from selective inhibition of right parietal regions integral for perceiving and evaluating emotional stimuli.

Attachment of primary neonatal rat astrocytes to vitronectin is mediated by integrins alphavbeta5 and alpha8beta1: modulation by the type 1 plasminogen activator inhibitor

Vitronectin is expressed in a cell-specific manner in the developing brain and concentrated in the brain during disease processes, such as germinal matrix hemorrhage and infarction, in which there is breakdown of the blood-brain barrier. In this study, we identified the integrin receptors that mediate attachment of primary neonatal rat astrocytes to vitronectin. Using fluorescent activated cell sorter and immunoprecipitation analyses, we established that the vitronectin receptor integrins alphavbeta5 and alpha8beta1, but not alphavbeta3, are expressed on neonatal rat astrocytes. Attachment of the neonatal astrocytes to vitronectin was inhibited (85%) in an additive manner by neutralizing anti-alphavbeta5 and anti-beta1 antibodies. Attachment to vitronectin was also inhibited in a dose-dependent manner by the type I plasminogen activator inhibitor (PAI-1), a serine protease inhibitor. Our data demonstrate that unstimulated primary neonatal rat astrocytes attach to vitronectin, utilizing integrins alphavbeta5 and alpha8beta1, and that this attachment is regulated by PAI-1.

Diffusional characteristics of freeze/thawed poly(vinyl alcohol) hydrogels: applications to protein controlled release from multilaminate devices

The incorporation of a model protein, bovine serum albumin (BSA), into poly(vinyl alcohol) (PVA) hydrogel films during the freezing and thawing process and its subsequent release behavior were investigated. The effect of the number of freezing and thawing cycles as well as the stability of BSA were examined. BSA release profiles were not significantly different from gels prepared after 3 or 5 cycles. However, the rate and overall amount of PVA dissolution were considerably higher for gels prepared after 3 cycles. These observations were then applied to the development of novel, freeze/thawed PVA laminates. Laminates containing gel layers prepared after 3 or 5 cycles were successfully prepared with good stability over a 6 month swelling period. These structures, containing distinct layers of very specific properties, could be used to achieve zero-order release behavior.

Microbial utilization of the neurotoxin domoic acid: blue mussels (Mytilus edulis) and soft shell clams (Mya arenaria) as sources of the microorganisms

The neurotoxin domoic acid is produced in quantity by the diatom Pseudo-nitzschia multiseries and is released to the environment directly and indirectly via food chains. Presumably there is a mechanism for the biodegradation and disposal of domoic acid and as bacteria are logical candidates for such an activity, a search for bacteria competent to carry out biodegradation of domoic acid was initiated. Extensive trials with a wide variety of bacteria isolated mainly from muds and waters taken from the marine environment showed that the ability to grow on or degrade domoic acid was rare; in fact, domoic acid was inhibitory to resting cells or growing cultures of most of these bacteria. In contrast, using enrichment techniques, it was possible to isolate from molluscan species that eliminate domoic acid readily, i.e., blue mussels (Mytilus edulis) and soft-shell clams (Mya arenaria), bacteria that exhibited growth with and biodegradation of domoic acid when supplemented with low concentrations of growth factors. The species that retain domoic acid for lengthy periods, such as sea scallops (Placopecten magellanicus) and red mussels (Modiolus modiolus), only occasionally yielded bacteria with this capability. The differences may be a result of the mechanisms used by the different shellfish in dealing with domoic acid, i.e., freely available in the blue mussels and soft-shell clams but likely sequestered in the digestive glands of sea scallops and red mussels and thus, largely unavailable for bacterial utilization. The results show that Mytilus edulis and Mya arenaria, almost uniquely, are prime and reliable sources of domoic acid utilizing bacteria. These findings suggest a strong possibility that autochthonous bacteria may be significant factors in the elimination of the neurotoxin in these two species of shellfish.

Large-scale preparation of the delta10 form of staphylokinase by in vitro processing of recombinant staphylokinase with purified human plasminogen

The authors have developed a rapid and convenient method for purification of a low molecular weight form (delta 10) of the bacterial plasminogen activator, staphylokinase. Recombinant staphylokinase is expressed in Escherichia coli, with an amino terminal extension that facilitated purification by immobilized metal-affinity chromatography. Purified staphylokinase is treated with human plasminogen, and the resulting truncated form is purified using a combination of immobilized metal affinity chromatography and hydrophobic interaction chromatography. Purified protein is characterized by amino terminal sequencing and in vitro plasminogen activation assay.

Receptor binding of an apolipoprotein E-rich subfraction of high density lipoprotein to rat and human brain membranes

During nerve cell degeneration, cholesterol released from the degrading cells is conserved through the formation of a cholesterol-apolipoprotein (apo) E complex which is subsequently taken up by regenerating nerve cells. The aim of the present project was to identify the physiologically relevant lipoprotein receptor for this lipoprotein complex which has remained elusive. HDL was separated into apo E-rich and apo E-poor subfractions and labelled with [14C]-sucrose. Labelled apo E-rich HDL bound to rat brain membranes in a time- and ligand concentration-dependent manner and was a saturable process. Essentially no binding occurred with [14C]-apo E-poor HDL or with free apo E. Binding was partially inhibited by low density lipoprotein (LDL) and by alpha 2-macroglobulin. These results provide new evidence that native apoE-rich HDL particles resembling those present in the brain bind to rat brain membranes and that the binding may be due, at least in part, to the LDL receptor and to the LDL-receptor related protein. Evidence was also provided for the presence of a receptor which binds [14C]-sucrose human apoE-rich HDL in human brain. Characterisation of the receptor which mediates the uptake of cholesterol from HDL-like complexes by brain cells is important in understanding the role of apoE in the central nervous system and of the alterations which occur in disorders such as Alzheimer's disease.

Brain ERPs of depressed patients to complex tones in an oddball task: relation of reduced P3 asymmetry to physical anhedonia

Event-related potentials to binaural complex tones were recorded from 40 depressed outpatients and 22 normal control participants at 30 electrode sites. Patients did not differ from control participants in N1 or P3 amplitude but showed greater N2. N2 was greater over right than over the left hemisphere at lateral sites in patients and control participants. A P3 asymmetry was found for control participants and patients with low scores on a physical anhedonia scale, but not for patients with high anhedonia scores. Topographic (local Laplacian) maps corresponding to P3 showed greater radial current flow over right than over left central regions in control participants. Patients with high anhedonia did not show this asymmetry, whereas patients with low anhedonia showed an intermediate asymmetry. These findings support the hypothesis that anhedonic depression is associated with dysfunction of right hemisphere mechanisms mediating the processing of complex pitch information.

Development of oral hygiene self-efficacy and outcome expectancy questionnaires

In order to measure social cognitive constructs in the oral hygiene domain, questionnaires containing self-efficacy and outcome expectation items were developed. Items were generated to measure personal beliefs in brushing and flossing ability under a variety of circumstances, and expected outcomes from performing oral hygiene behaviors that might be positive, negative, primary and secondary. In the first study, factor scales were developed on the basis of the responses from 90 subjects awaiting dental treatment. Principal components analyses with varimax rotation revealed two self-efficacy and four outcome expectations dimensions that explained 73% and 51% of the variance, respectively. A second study that utilized 103 government employees was conducted to evaluate the psychometric properties of the questionnaires. All scales demonstrated good internal consistency and test-retest stability. Correlations with extra test measures provided preliminary evidence for the validity of the instruments.

Preliminary crystallographic study on a low molecular weight form of bacterial plasminogen activator staphylokinase

Staphylokinase, a 17 kDa protein, produced by certain strains of Staphylococcus aureus functions as a fibrin-specific plasminogen activator. During its interaction with plasminogen, staphylokinase is converted into a low molecular weight form by loss of ten amino-terminal residues. This low molecular weight form of recombinant staphylokinase has been crystallized using the hanging-drop vapor-diffusion technique with polyethylene glycol 4000 as precipitant. Crystals belong to the orthorhombic space group C222(1) with unit-cell dimensions a = 43.78, b = 59.86 and c = 103.25 A and one molecule in the asymmetric unit. These crystals diffract to about 2.4 A resolution.

Regional brain asymmetries in major depression with or without an anxiety disorder: a quantitative electroencephalographic study

Studies of brain activity in affective disorders need to distinguish between effects of depression and anxiety because of the substantial comorbidity of these disorders. Based on a model of asymmetric hemispheric activity in depression and anxiety, it was predicted that anxious and nonanxious depressed patients would differ on electroencephalographic (EEG) measures of parietotemporal activity. Resting EEG (eyes closed and eyes open) was recorded from 44 unmedicated outpatients having a unipolar major depressive disorder (19 with and 25 without an anxiety disorder), and 26 normal controls using 30 scalp electrodes (13 homologous pairs over the two hemispheres and four midline sites). As predicted, depressed patients with an anxiety disorder differed from those without an anxiety disorder in alpha asymmetry. Nonanxious depressed patients showed an alpha asymmetry indicative of less activation over right than left posterior sites, whereas anxious depressed patients showed evidence of greater activation over right than left anterior and posterior sites. The findings are discussed in terms of a model in which specific symptom features of depression and anxiety are related to different patterns of regional brain activity.

Growth inhibition of cultured fibroblasts by extracts from human dermis

In incised wounds and deep partial thickness burns the resident fibroblasts in the dermis remain inactive. The fibroblasts responsible for repair at the dermal level come from the subdermal layer. The hypothesis is that the inactivity of the dermal fibroblasts is due to an inhibitory substance in the dermis. To test this hypothesis extracts were made of normal dermis and of mature scar tissue and these extracts were applied to fibroblasts growing in monolayer culture. Both extracts and cells were obtained from human tissue. It was shown that extracts, particularly the extract made with citric acid/citrate buffer, pH 3.5, caused inhibition of fibroblast growth. Present evidence suggests that the active principle may be a proteoglycan.

Changes in dental knowledge and self-efficacy scores following interventions to change oral hygiene behavior

One hundred twenty-three male veterans were randomly assigned to control, education, and psychological groups to improve oral hygiene behavior. The educational group received four 40-min sessions designed to increase knowledge of the causes and prevention of dental disease. The psychological intervention also consisted of four 40-min sessions. However, a psychologist provided the intervention using a Stage of Change intervention. The control group received pre- and post-testing only. There were no significant changes in dental knowledge for the control group while the increases in dental knowledge in the educational and psychological groups were similar and statistically significant. Pre-Post change scores for flossing self-efficacy scores showed significant changes for all groups. The magnitude of changes was similar when the control and educational groups were compared. In contrast, the psychological intervention group demonstrated significantly greater flossing self-efficacy changes when compared to either the control or the educational groups. These results suggest that increases in self-efficacy may be an important component of interventions designed to change health behavior and may serve a role in evaluating and comparing the efficacy of these interventions.

Autism: is there a biological cause?

1. Autism is the term used to describe certain characteristics observed in some children, including a preference for aloneness, and sameness. 2. The condition was thought for some time to be caused by a psychological disturbance resulting from a combination of stress and poor parental upbringing. 3. Recently emerging data suggests the symptoms are related to a cognitive deficit associated with a biological cause. 4. As research progresses, it is hoped it will become possible to improve the quality of life for people suffering from or looking after those with, autism.

Approximate phase conjugation with a retroreflecting array in microscopy

Some experiments on image recovery in microscopy are described. The aperture stop of a microscope objective is partially obscured, and a retroreflecting array is used as an approximate phase conjugator to return the beam through the unobstructed part of the aperture. An application is made to the measurement of the absolute reflectance of small samples by use of a variant of Strong's method.

Diagnosis and treatment of phobia

A phobia is an excessive fear or dread of a situation or object which is out of keeping with the danger it may actually present. Phobias can be classified into 'simple phobias', 'social phobias' and agoraphobia. A number of psychological theories have been put forward to account for both the onset and maintenance of a phobia. The case of a social phobia is presented together with a cognitive behavioural intervention package.

The cognitive model and treatment of depression

1. Research indicates that depression is best treated using a combination of drugs and psychological interventions. 2. The Beck psychological model of depression has led to a specific treatment formulation. 3. Beck sees the dysfunctional cognitions which arise in how person sees him- or herself, the world, the future, as contributory to the illness. 4. Research using both qualitative and quantitative analysis has shown cognitive therapy to be an effective form of treatment for depression.

Reliability of filter-strip sampling of gingival crevicular fluid for volume determination using the Periotron

This study explored gingival cervicular fluid (GCF) volumes as measured by the Periotron in an attempt to find a more objective measure of gingival inflammation that could be used in dental compliance studies. The first step in this process was to assess the reliability of the method of collecting and determining GCF volumes as described by the manufacturer. Collections of GCF from both the buccal and lingual surfaces of 6 teeth from 18 subjects with good to moderate plaque accumulation was accomplished. At a later time these same surfaces were retested for a comparison with the initial value for reliability determination. We found that only 23% of the tooth surface pairs varied by less than 20% and 57% of these pairs differed by at least 50%. These values were similar for both good and moderate plaque accumulation subjects. In these subjects, reliability measurements at individual tooth surfaces did not approach acceptable levels of reliability. However, when the GCF values from the 12 tooth surfaces were averaged for each subject, differences between the two measurements improved markedly. Sixty-one percent of these subject pairs differed by less than 20%. Therefore, the average GCF value from subjects with good to moderate plaque accumulations may be compared with reasonable accuracy.

Paralytic shellfish poison (saxitoxin family) bioassays: automated endpoint determination and standardization of the in vitro tissue culture bioassay, and comparison with the standard mouse bioassay

Mouse neuroblastoma cells swell and eventually lyse upon exposure to veratridine, which, when added together with ouabain, enhances sodium ion influx. In the presence of saxitoxin (STX), which blocks sodium channels, the action of the other two compounds is inhibited and the cells remain morphologically normal. A tissue culture bioassay using mouse neuroblastoma cells, developed by Kogure and colleagues, takes advantage of these principles; in this bioassay, the fraction of the cells protected from the actions of ouabain and veratridine is in direct proportion to the concentration of STX and its analogues. We have modified this bioassay, improving its convenience and speed by eliminating the need to count individual cells to determine the saxitoxin equivalents, and instead have employed a microplate reader for automated determinations of absorbances of crystal violet from stained neuroblastoma cells. When these changes and other minor technical modifications were tested in the tissue culture bioassay systematically, we found the lower detection limit to be around 10 ng STX equivalents (eq) per ml of extract ( = 2.0 micrograms STX eq/100 g shellfish tissue). Our version of the tissue culture bioassay was compared with the standard mouse bioassay using 10 acid extracts of dinoflagellates (Alexandrium excavata and A. fundyense) and 47 AOAC extracts of shellfish tissues. The tissue culture bioassay provided results virtually identical to those obtained with the mouse bioassay (r > 0.96), and moreover, was considerably more sensitive. The results gained from high performance liquid chromatographic (HPLC) analysis of 12 of the same extracts were less consistent when compared with the results from both bioassay methods. The automated tissue culture (neuroblastoma cell) bioassay may be a valid alternative to live animal testing for paralytic shellfish poisoning.

Pharmacist work activity before and after pharmacy department computerization

The effects of a dedicated computer system on pharmacists' daily activities at a 363-bed hospital were studied. A one-group pretest-posttest design was used. Twenty-four pharmacists recorded activity frequency and time for seven consecutive days several months before and after a pharmacy computer system was implemented. The computer system could be used for printing unit dose fill lists and i.v. labels, entering data, and printing patient profiles. An admissions, discharge, and transfer interface between the hospital system and the pharmacy system was also operational. The data were organized into 28 activities for analysis. For seven activities that were considered directly affected by computerization, a net 0.1-minute increase in the average time was found. Four of those seven showed an increase in average time (a total of 1.86 minutes): (1) calculating the composition of total parenteral nutrient or i.v. solution, (2) compounding large-volume i.v. solution, (3) profiling orders, and (4) checking the work of pharmacy technicians. The other three showed a decrease in average time (a total of 1.76 minutes): (1) preparing syringe or small-volume i.v. solution, (2) monitoring drug profiles, and (3) dispensing unit dose medications. However, with all 28 activities considered, a 1.03-minute decrease occurred in the average time per activity. Installation of a dedicated pharmacy computer decreased the amount of time pharmacists spent performing 28 activities by an average of 1.03 minutes per activity but increased the amount of time spent on activities directly affected by the computer by an average of 0.1 minute per activity.

Modulation of locomotor patterns and spasticity with clonidine in spinal cord injured patients

This double blind cross-over study, involving 9 chronic spinal cord injured (SCI) patients (6 paraplegic and 3 paretic), was a first attempt to investigate the effects of the noradrenergic agonist, clonidine, on the modulation of the locomotor pattern and spasticity in patients with spinal cord lesions. Electromyographic (EMG), footswitch and video recordings were made as the patients walked on a treadmill with the support of an overhead harness if needed. Overground locomotion was also assessed in the paretic patients. All 3 spastic paretic patients had kinematic deviations and abnormal EMG recruitment profiles during the premedication or placebo sessions. With clonidine therapy one patient demonstrated a marked improvement in locomotor function. This patient progressed from non-ambulation to limited independent ambulation as the extent of coactivation in antagonist muscles decreased. The other 2 paretics who presented limited spasticity showed minimal changes while on clonidine. In the paraplegic patients, clonidine did not elicit locomotor activity, although there were marked reductions in stretch reactions and clonus during assisted locomotion. They remained incapable of locomotion, either during the control period or during the clonidine therapy. These results indicate that clonidine may be a potentially useful medication for both locomotion and certain manifestations of spasticity in SCI patients but further investigation is warranted.