Advances in light system engineering across the phototrophic spectrum

Current work in photosynthetic engineering is progressing along the lines of cyanobacterial, microalgal, and plant research. These are interconnected through the fundamental mechanisms of photosynthesis and advances in one field can often be leveraged to improve another. It is worthwhile for researchers specializing in one or more of these systems to be aware of the work being done across the entire research space as parallel advances of techniques and experimental approaches can often be applied across the field of photosynthesis research. This review focuses on research published in recent years related to the light reactions of photosynthesis in cyanobacteria, eukaryotic algae, and plants. Highlighted are attempts to improve photosynthetic efficiency, and subsequent biomass production. Also discussed are studies on cross-field heterologous expression, and related work on augmented and novel light capture systems. This is reviewed in the context of translatability in research across diverse photosynthetic organisms.

Proximate biomass characterization of the high productivity marine microalga Picochlorum celeri TG2

Microalgae are compelling renewable resources with applications including biofuels, bioplastics, nutrient supplements, and cosmetic products. Picochlorum celeri is an alga with high industrial interest due to exemplary outdoor areal biomass productivities in seawater. Detailed proximate analysis is needed in multiple environmental conditions to understand the dynamic biomass compositions of P. celeri, and how these compositions might be leveraged in biotechnological applications. In this study, biomass characterization of P. celeri was performed under nutrient-replete, nitrogen-restricted, and hyper-saline conditions. Nutrient-replete cultivation of P. celeri resulted in protein-rich biomass (∼50% ash-free dry weight) with smaller carbohydrate (∼12% ash-free dry weight) and lipid (∼11% ash-free dry weight) partitions. Gradual nitrogen depletion elicited a shift from proteins to carbohydrates (∼50% ash-free dry weight, day 3) as cells transitioned into the production of storage metabolites. Importantly, dilutions in nitrogen-restricted 40 parts per million (1.43 mM nitrogen) media generated high-carbohydrate (∼50% ash-free dry weight) biomass without substantially compromising biomass productivity (36 g ash-free dry weight m-2 day-1) despite decreased chlorophyll (∼2% ash-free dry weight) content. This strategy for increasing carbohydrate content allowed for the targeted production of polysaccharides, which could potentially be utilized to produce fuels, oligosaccharides, and bioplastics. Cultivation at 2X sea salts resulted in a shift towards carbohydrates from protein, with significantly increased levels of the amino acid proline, which putatively acts as an osmolyte. A detailed understanding of the biomass composition of P. celeri in nutrient-replete, nitrogen-restricted, and hyper saline conditions informs how this strain can be useful in the production of biotechnological products.

Can machine learning augment clinician adjudication of events in cardiovascular trials? A case study of major adverse cardiovascular events (MACE) across CVRM trials

Background and introduction

Accurate identification of clinical outcome events is critical to obtaining reliable results in cardiovascular outcomes trials (CVOTs). Current processes for event adjudication are expensive and hampered by delays. As part of a larger project to more reliably identify outcomes, we evaluated the use of machine learning to automate event adjudication using data from the SOCRATES trial (NCT01994720), a large randomized trial comparing ticagrelor and aspirin in reducing risk of major cardiovascular events after acute ischemic stroke or transient ischemic attack (TIA).

Purpose

We studied whether machine learning algorithms could replicate the outcome of the expert adjudication process for clinical events of ischemic stroke and TIA. Could classification models be trained on historical CVOT data and demonstrate performance comparable to human adjudicators?

Methods

Using data from the SOCRATES trial, multiple machine learning algorithms were tested using grid search and cross validation. Models tested included Support Vector Machines, Random Forest and XGBoost. Performance was assessed on a validation subset of the adjudication data not used for training or testing in model development. Metrics used to evaluate model performance were Receiver Operating Characteristic (ROC), Matthews Correlation Coefficient, Precision and Recall. The contribution of features, attributes of data used by the algorithm as it is trained to classify an event, that contributed to a classification were examined using both Mutual Information and Recursive Feature Elimination.

Results

Classification models were trained on historical CVOT data using adjudicator consensus decision as the ground truth. Best performance was observed on models trained to classify ischemic stroke (ROC 0.95) and TIA (ROC 0.97). Top ranked features that contributed to classification of Ischemic Stroke or TIA corresponded to site investigator decision or variables used to define the event in the trial charter, such as duration of symptoms. Model performance was comparable across the different machine learning algorithms tested with XGBoost demonstrating the best ROC on the validation set for correctly classifying both stroke and TIA.

Conclusions

Our results indicate that machine learning may augment or even replace clinician adjudication in clinical trials, with potential to gain efficiencies, speed up clinical development, and retain reliability. Our current models demonstrate good performance at binary classification of ischemic stroke and TIA within a single CVOT with high consistency and accuracy between automated and clinician adjudication. Further work will focus on harmonizing features between multiple historical clinical trials and training models to classify several different endpoint events across trials. Our aim is to utilize these clinical trial datasets to optimize the delivery of CVOTs in further cardiovascular drug development.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): AstraZenca Plc

SAT0189 SAMPLE SIZES AND RECRUITMENT RATES ARE DECREASING WHILE PLACEBO RESPONSE RATES ARE INCREASING IN CLINICAL TRIALS FOR SYSTEMIC LUPUS ERYTHEMATOSUS - A MANDATE FOR NEW STRATEGIES

Background:

Randomized controlled trials in Systemic Lupus (SLE) have shown disappointing results for decades. Key challenges may include the heterogenous population coupled with high placebo response rates.

Objectives:

To evaluate trends in SLE study metrics over time and explore associations between primary endpoint failure and response in placebo/standard of care arms.

Methods:

Data from Phase II or III trials which enrolled ≥ 100 patients with SLE and reported SRI-4 and/or BICLA responses after a minimum of 24 weeks were included in the analysis. Sample size, recruitment rates, regional patient distributions, and results in placebo arms (at 24-36 weeks or 48-52 weeks) were examined according to the start date of each study in order to determine trends over time. Placebo group SRI-4 response rates in studies that met their primary endpoint were compared with those that did not.

Results:

Twenty-seven (14 phase II and 13 phase III) studies met the search criteria. Eleven of them met their primary endpoints. The study start dates ranged from Dec 2006 to Jan 2017. Mean/median total subject numbers were 461/349. Mean/median placebo subjects’ age at baseline were 39.9/39.2 and SLEDAI: 10.6/10.6. Mean/median placebo SRI-4 responses at Week 24-36 were 47.2%/45.8% and 42.8%/43% at Week 48-52. For BICLA, the rates were 40.3%/37.2% at Week 24-36 and 33.2%/33.5% at Week 48-52.

As expected, lower placebo response was found in trials that met primary endpoints vs studies that did not (p=0.005). Total subject numbers and recruitment rates decreased over time while placebo SRI-4 response rates increased overall (Figure). However, there has been a greater range of placebo responses in more recent trials. Similar trends were observed in BICLA responses at Week 24-36 and 48-52, and in a corticosteroid reduction endpoint (percent of patients with reduction in steroid dose by ≥25% and to ≤7.5 mg/day prednisone/equivalent) at Week 48-52. Enrollment of patients from North America decreased while proportions of Eastern Europeans increased over time (Figure).

Conclusion:

High placebo response rates pose a continuing challenge in SLE studies and are associated with primary endpoint failures.

Clinical trial metrics have been changing over time, with declining size and recruitment rates, possibly due to competition from increasing numbers of studies.

These trends should be considered while designing and conducting future trials. Attention to site training and data quality may be particularly important to control high placebo rates, especially as trial sizes decrease.

Figure.

Disclosure of Interests:

Ewa Olech Grant/research support from: BMS, Consultant of: Abbvie, Amgen, Remegen, Employee of: IQVIA, Speakers bureau: Abbvie, Amgen, Merck, Pfizer, UCB, Eduard van Rijen Employee of: IQVIA, Faizi Hussain Employee of: IQVIA, Gregory Dennis Employee of: IQVIA, Ali Ashrafzadeh Employee of: IQVIA, Joan T Merrill Grant/research support from: Xencor, Bristol Myers Squibb, Glaxo Smith Kline, Consultant of: Xencor, Abbvie, UCB, Glaxo Smith Kline, EMD Serono, Astellas, Remegen, Celgene/Bristol Myers Squibb, Exagen, Astra Zeneca, Amgen, Jannsen, Servier, ILTOO, Daitchi Sankyo, Lilly, Paid instructor for: Abbvie, Bristol Myers Squibb

Burden of corticosteroid use in patients with systemic lupus erythematosus: results from a Delphi panel

Corticosteroid-related adverse events (AEs) are commonly reported in systemic lupus erythematosus (SLE), but are often under-represented in claims data. The most common corticosteroid-related AEs are not necessarily the most costly. The present study aimed to examine corticosteroid-related AE rates and identify the associated cost consequences in patients with SLE from the perspective of rheumatologists treating SLE in the United States (US). A modified Delphi process and RAND Appropriateness Method was used to estimate corticosteroid-related AEs and costs based on data from SLE-treating US rheumatologists and estimates from alternative sources. The panel (n=10) participated in two web-based questionnaires, covering disease severity, corticosteroid use, corticosteroid-related AEs, and resource utilization associated with treatment of the AEs. Eight members of the panel then participated in a guided discussion by interactive teleconference, in which the costs associated with specific corticosteroid-related AEs were also discussed. Consensus was achieved in the teleconference when a single response category (consensus values from 1 to 4 [4=strongly agree, 1=strongly disagree]) accounted for ≥80% of responses. Thirteen consensus statements were developed following two Delphi rounds. Costs were estimated for eight corticosteroid-associated AEs from the panel of rheumatologists. In the patients with SLE treated by these physicians, 41.5% were considered to have mild disease, 36.5% moderate disease, and 22.0% severe disease. The number of specialist visits, corticosteroid use, and corticosteroid dose increased with disease severity. The estimated rates of all AEs (except for cataracts) were at least doubled in patients receiving corticosteroid doses>20 mg/day compared with ≤20 mg/day. The highest estimated mean total costs of an event (for the required treatment duration for one patient) were for avascular necrosis ($14,460) and serious infection ($11,660). The costs of more common AEs, such as osteoporosis, obesity, diabetes, and fractures, ranged from $1190 to $8220. Ten rheumatologists concluded that as disease severity increases, corticosteroid doses increased. Greater utilization of resources is needed to manage patients and corticosteroid-related AEs.

Toughening effect of strain-induced crystallites in natural rubber

We study fracture propagation in stretched natural rubber sheets. Experimental results in specimens stretched less than 3.8 times show a monotonic increase in the crack speed with stretch and can be explained by a numerical model based on neo-Hookean theory and Kelvin dissipation. In specimens stretched more than 3.8 times, strain-induced crystallites act as reinforcing and toughening fillers and significantly increase fracture resistance, like nanostructures in other polymeric or biological materials. Consequently, as we increase the amount of stretch, fractures travel slower and slower, and eventually halt altogether.

A column capacity study of single, serial, and parallel linked rod monolithic high performance liquid chromatography columns

The loading capacity of rod monolithic C18 columns was found to be sensitive to the injection volume, but essentially insensitive to the mass loading for a separation of oligostyrenes. When rod monoliths were coupled in series the injection volume loading increased, as too did the resolution of the oligomers, but at the expense of separation time. The volume load capacity of these serially connected monoliths was, however, not directly proportional to the number of columns connected. The volume load capacity was, however, directly proportional to the number of columns when the monoliths were connected in parallel and the flow stream split between each of the monolithic channels. When the number of monoliths in each channel equaled the number of monoliths that were connected in a single channel serial system the peak capacity and retention time was equivalent for both systems, but the volume load capacity of the parallel system was twice that of the serial connection each time the number of channels doubled. The results of this study indicate that parallel connection of rod monolithic columns may be useful for preparative scale and multidimensional separations where it is important that the volume load capacity is high.

Genomic structure of mouse PIR-A6, an activating member of the paired immunoglobulin-like receptor gene family

The gene for one of the activating members of the paired Ig-like receptor family, Pira6, was isolated from a genomic library and sequenced. The first of 9 exons in the approximately 8.2 kb Pira6 gene encodes the 5' untranslated region, the translation initiation site, and approximately half of the signal sequence. The second exon encodes the rest of the signal sequence, exons 3-8 each encode a single Ig-like extracellular domain, and exon 9 encodes the transmembrane region, cytoplasmic tail and 3' UTR with four polyadenylation signals and six mRNA instability sequences. A soluble form of PIR-A6 may be generated by alternative splicing. The exonic sequences account for approximately 42% of the Pira6 gene and approximately 34% for the single inhibitory Pirb gene, thus defining Pira and Pirb as genes with relatively short intronic sequences. Extensive sequence homology was found between Pira6 and Pirb from approximately 2 kb upstream of the ATG initiation site to the beginning of intron 8. The Pir genes appear to be distributed in three regions of the proximal end of chromosome 7 based on the present data and an analysis of currently available mouse genomic sequence databases. One region contains a single Pir gene which is almost identical to Pira6, and the other two contain multiple Pir genes in opposite transcriptional orientations. Potential binding sites for hemopoiesis-specific and ubiquitous transcription factors were identified upstream of the Pira6 transcription start sites that reside within the initiator consensus sequence motif. These results provide important clues to the coordinate regulation observed for PIR-A and PIR-B expression during hematopoiesis.

Fc epsilon receptor type I gamma chain replaces the deficient T cell receptor zeta chain in T cells of patients with systemic lupus erythematosus

OBJECTIVE

T cells from the majority of patients with systemic lupus erythematosus (SLE) express significantly lower levels of T cell receptor zeta chain, a critical signaling molecule. However, TCR/CD3 triggering of SLE T cells shows increased phosphorylation of downstream signaling intermediates and increased [Ca2+]i response, suggesting the presence of alternative signaling mechanisms. We investigated whether Fcepsilon receptor type I gamma chain (FcepsilonRIgamma) could substitute for TCR zeta chain and contribute to T cell signaling in SLE.

METHODS

T cells were purified from the peripheral blood of 21 patients with SLE and 5 healthy volunteers. The expression of FcepsilonRIgamma was investigated using immunoblotting, reverse transcriptase-polymerase chain reaction, and flow cytometry methods. Involvement of the FcepsilonRIgamma in T cell signaling was studied by immunoprecipitation and/or immunoblotting after TCR/CD3 stimulation.

RESULTS

Western blotting and densitometric analysis showed that the expression of FcepsilonRIgamma in SLE T cells was 4.3-fold higher than in normal T cells (P < 0.001). Flow cytometric analyses of T lymphocyte subsets revealed that the proportions of FcepsilonRIgamma+,CD3+, FcepsilonRIgamma+,CD4+, and FcepsilonRIgamma+, CD8+ cells were significantly greater in SLE patients than in healthy controls (P < 0.001). Immunoprecipitation of SLE T cell lysates with an anti-FcepsilonRIgamma antibody showed that FcepsilonRIgamma associates with the tyrosine kinase Syk and the CD3epsilon chain, suggesting that FcepsilonRIgamma is functionally involved in TCR signaling.

CONCLUSION

These results demonstrate that the FcepsilonRIgamma chain is expressed at high levels in a large proportion of SLE T cells. The increased expression of FcepsilonRIgamma chain in SLE T cells may account in part for the aberrant antigen receptor-initiated signaling and contribute to the diverse cellular abnormalities found in this disease.

T cell signaling abnormalities in systemic lupus erythematosus are associated with increased mutations/polymorphisms and splice variants of T cell receptor zeta chain messenger RNA

OBJECTIVE

T cells from patients with systemic lupus erythematosus (SLE) display antigen receptor-mediated signaling aberrations associated with defective T cell receptor (TCR) zeta chain protein and messenger RNA (mRNA) expression. This study was undertaken to explore the possibility that coding-region mutations/polymorphisms of the TCR zeta chain could account for its decreased expression and altered signaling in SLE T cells.

METHODS

TCR zeta chain mRNA from 48 SLE patients, 18 disease controls, and 21 healthy volunteers was reverse transcribed, amplified by polymerase chain reaction, and cloned, and complementary DNA (cDNA) was sequenced. DNA sequences from multiple clones were analyzed for silent single-nucleotide polymorphisms, mutations, and splice variations, to promote the identification of heterozygosity.

RESULTS

DNA sequence analysis revealed several widely distributed missense mutations and silent polymorphisms in the coding region of the TCR zeta chain, which were more frequent in SLE patients than in patients with other rheumatic diseases or healthy controls (P < 0.0001). Several of the missense mutations were located in the 3 immunoreceptor tyrosine activation motifs or the GTP binding domain, and this could lead to functional alterations in the TCR zeta chain. A splice variant of the TCR zeta chain with a codon CAG (glutamine) insertion between exons IV and V was found in half of the SLE and control samples. Two larger spliced isoforms of the TCR zeta chain, with an insertion of 145 bases and 93 bases between exons I and II, were found only in SLE T cells. We also identified various alternatively spliced forms of the TCR zeta chain resulting from the deletion of individual exons II, VI, or VII, or a combined deletion of exons V and VI; VI and VII; II, III, and IV; or V, VI, and VII in SLE T cells. The frequency of the deletion splice variants was significantly higher in SLE than in control samples (P = 0.004). These variations were observed in cDNA and may not reflect the status of the genomic DNA.

CONCLUSION

These findings demonstrate that heterogeneous mutations/polymorphisms and alternative splicing of TCR zeta chain cDNA are more frequent in SLE T cells than in T cells from non-SLE subjects and may underlie the molecular basis of known T cell signaling abnormalities in this disease.

Polymorphisms/mutations of TCR-zeta-chain promoter and 3' untranslated region and selective expression of TCR zeta-chain with an alternatively spliced 3' untranslated region in patients with systemic lupus erythematosus

A vast majority of systemic lupus erythematosus (SLE) patients display decreased expression of TCR zeta-chain mRNA, a critical signaling molecule implicated in the selection of the TCR repertoire and in the prevention of autoimmunity. To identify the molecular mechanisms involved in the downregulation of TCR zeta-chain transcripts in SLE T cells, we investigated the possibility of polymorphisms/mutations in the promoter and the 3' untranslated region. PCR, cloning and sequence analysis of the promoter region from the genomic DNA showed significantly higher number of polymorphisms in SLE T cells compared to non-SLE control subjects (P = 0.044). Promoter sequence was also analysed from granulocytes to delineate the possibility of somatic mutations in activated SLE T cells. Promoter polymorphisms were significantly higher in granulocytes of SLE patients compared to non-SLE controls (P = 0.048), suggesting that these polymorphisms were of genomic origin. Nucleotide analysis of the promoter sequence revealed a -76T insertion compared to the published sequence, in all of the SLE samples and controls. RT-PCR analysis of the TCR zeta-chain 3' untranslated region showed a 344 bp product in addition to the expected 906 bp product. Cloning and sequence analysis of the 344 bp product indicated that it is an alternatively spliced form with both splicing donor and acceptor sites, resulting in deletion of nucleotides 672-1233 of TCR zeta-chain mRNA. Unlike the nomal TCR zeta-chain, the expression of TCR zeta-chain with the alternatively spliced 344 bp 3' untranslated region was higher in SLE T cells compared to non-SLE controls. The number of mutations/polymorphisms in the 906 bp TCR zeta-chain 3' untranslated region were significantly higher in SLE T cells compared to non-SLE subjects (P = 0.032). Frequent mutations/polymorphisms and aberrant splicing of the downstream 3' untranslated region may affect the stability and/or transport of TCR zeta-chain mRNA, leading to its downregulation in SLE T cells.

Paired Ig-like receptor homologs in birds and mammals share a common ancestor with mammalian Fc receptors

Paired Ig-like receptors (PIR) that can reciprocally modulate cellular activation have been described in mammals. In the present study, we searched expressed sequence tag databases for PIR relatives to identify chicken expressed sequence tags predictive of approximately 25% amino acid identity to mouse PIR. Rapid amplification of cDNA ends (RACE)-PCR extension of expressed sequence-tag sequences using chicken splenic cDNA as a template yielded two distinct cDNAs, the sequence analysis of which predicted protein products with related extracellular Ig-like domains. Chicken Ig-like receptor (CHIR)-A was characterized by its transmembrane segment with a positively charged histidine residue and short cytoplasmic tail, thereby identifying CHIR-A as a candidate-activating receptor. Conversely, CHIR-B was characterized by its nonpolar transmembrane segment and cytoplasmic tail with two immunoreceptor tyrosine-based inhibitory motifs, indicating that it may serve as an inhibitory receptor. The use of CHIR amino acid sequences in a search for other PIR relatives led to the recognition of mammalian Fc receptors as distantly related genes. Comparative analyses based on amino acid sequences and three-dimensional protein structures provided molecular evidence for common ancestry of the PIR and Fc receptor gene families.

New variant Creutzfeldt-Jakob disease: three case reports from Leicestershire

Since a report in 1996 of 10 cases of Creutzfeldt-Jakob disease (CJD) with onset in a younger than usual age, a pattern of the disease has emerged. This includes early neuropsychiatric features and sensory symptoms and neurological signs such as ataxia and involuntary movements later in the course of the disease. Three patients with varied clinical presentations and disease course seen at a single neurology unit are described. The first patient was characterised by cognitive and psychiatric symptoms together with neurological signs. The second patient presented with unusual behavioural disturbance and episodes of collapse. The third patient exhibited striking psychomotor retardation and had abnormal CSF and MRI findings. All patients succumbed in a state of akinetic mutism and myoclonus. All three patients had the methionine/methionine genotype at codon 129 of the PrP gene and in two of the three patients a tonsil biopsy was performed with positive results. These two patients also tested positive for the 14.3.3. protein in the CSF. Whereas late features of the disease seem very similar in all cases, the initial presentation was variable and underlines the uncertainty of the range of the clinical phenotype. Successful diagnosis demands a high index of clinical suspicion.

Characterization of paired Ig-like receptors in rats

To explore the phylogenetic history of the murine paired Ig-like receptors of activating (PIR-A) and inhibitory (PIR-B) types, we isolated PIR homologues from a rat splenocyte cDNA library. The rat (ra) PIR-A and raPIR-B cDNA sequences predict transmembrane proteins with six highly conserved extracellular Ig-like domains and distinctive membrane proximal, transmembrane, and cytoplasmic regions. The raPIR-B cytoplasmic region contains prototypic inhibitory motifs, whereas raPIR-A features a charged transmembrane region and a short cytoplasmic tail. Southern blot analysis predicts the presence of multiple Pira genes and a single Pirb gene in the rat genome. Although raPIR-A and raPIR-B are coordinately expressed by myeloid cells, analysis of mRNA detected unpaired expression of raPIR-A by B cells and raPIR-B by NK cells. Collectively, these findings indicate that the structural hallmarks of the Pir gene family are conserved in rats and mice, yet suggest divergence of PIR regulatory elements during rodent speciation.

Abnormal NF-kappa B activity in T lymphocytes from patients with systemic lupus erythematosus is associated with decreased p65-RelA protein expression

Numerous cellular and biochemical abnormalities in immune regulation have been described in patients with systemic lupus erythematosus (SLE), including surface Ag receptor-initiated signaling events and lymphokine production. Because NF-kappa B contributes to the transcription of numerous inflammatory genes and has been shown to be a molecular target of antiinflammatory drugs, we sought to characterize the functional role of the NF-kappa B protein complex in lupus T cells. Freshly isolated T cells from lupus patients, rheumatoid arthritis (RA) patients, and normal individuals were activated physiologically via the TCR with anti-CD3 and anti-CD28 Abs to assess proximal membrane signaling, and with PMA and a calcium ionophore (A23187) to bypass membrane-mediated signaling events. We measured the NF-kappa B binding activity in nuclear extracts by gel shift analysis. When compared with normal cells, the activation of NF-kappa B activity in SLE patients was significantly decreased in SLE, but not in RA, patients. NF-kappa B binding activity was absent in several SLE patients who were not receiving any medication, including corticosteroids. Also, NF-kappa B activity remained absent in follow-up studies. In supershift experiments using specific Abs, we showed that, in the group of SLE patients who displayed undetectable NF-kappa B activity, p65 complexes were not formed. Finally, immunoblot analysis of nuclear extracts showed decreased or absent p65 protein levels. As p65 complexes are transcriptionally active in comparison to the p50 homodimer, this novel finding may provide insight on the origin of abnormal cytokine or other gene transcription in SLE patients.

Visual organization test performance in an African American population with acute unilateral cerebral lesions

Controversy abounds as to whether the Hooper Visual Organization Test (VOT) is a measure of hemisphere-specific, region-specific, or non-specific brain damage. The present study examines this issue in a group of African Americans with acute unilateral brain damage and non-brain-injured controls. Consistent with the idea that the VOT is a measure of "organic" cerebral pathology, non-brain damaged controls earned significantly higher VOT scores than brain-damaged patients. While other studies have noted that the VOT is primarily sensitive to damage in the right parietal region of the brain, the present study shows that VOT performance is especially vulnerable to acute lesions in the right anterior quadrant of the brain. This latter finding supports the idea that VOT performance is differentially sensitive to regional cerebral pathology, but challenges the region specific claim of poorer VOT performance among patients with right posterior cerebral damage.

Unilateral brain lesions and performance on Russell's version of the Wechsler Memory Scale in an African American population

Studies of patients with unilateral lesions report hemisphere-specific and locus-specific impairments on Russell's (1975) Revision of the Wechsler Memory Scale (RWMS). In the current investigation "race-homogeneous" and "race-comparative" paradigms provide the context in which the generalizability of RWMS findings are examined in a population of African Americans with unilateral lesions. The performances of brain-damaged patients were impaired relative to normal controls on five of the six RWMS measures. However, patients with left and right hemisphere damage in our sample did not differ systematically on RWMS subtests. Likewise, among patients with lesions confined to one of the quadrants in the brain, there were no quadrant group differences in performance on RWMS subtests. But, right posteriors were impaired relative to controls on immediate and delayed VR subtests. The relative merits of the race-comparative and race-homogeneous paradigms are considered in the context of these findings.

B cells from patients with systemic lupus erythematosus display abnormal antigen receptor-mediated early signal transduction events

To understand the molecular mechanisms that are responsible for the B cell overactivity that is observed in patients with SLE, we have conducted experiments in which the surface immunoglobulin (sIg)-mediated early cell signaling events were studied. The anti-sIgM-mediated free intracytoplasmic calcium ([Ca2+]i) responses were significantly higher in SLE B cells compared with responses of normal individuals and to those of patients with other systemic autoimmune rheumatic diseases. The anti-IgD mAb induced [Ca2+]i responses were also higher in lupus B cells than in controls. The magnitude of anti-sIgM-mediated Ca2+ release from intracellular stores was also increased in B cells from SLE patients compared with normal controls. The amount of inositol phosphate metabolites produced upon crosslinking of sIgM was slightly higher in patients with lupus than in normal controls, although the difference was not statistically significant. In contrast, the degree of anti-sIgM-induced protein tyrosine phosphorylation was obviously increased in lupus patients. Our study demonstrates clearly for the first time that SLE B cells exhibit aberrant early signal transduction events, including augmented calcium responses after crosslinking of the B cell receptor and increased antigen-receptor-mediated phosphorylation of protein tyrosine residues. Because the above abnormalities did not correlate with disease activity or treatment status, we propose that they may have pathogenic significance.

The relationship between hepatic copper content and morphologic changes in the liver of West Highland White Terriers

Liver tissue from 17 West Highland White Terriers (WHWTs) with cirrhosis, subacute bridging necrosis, hepatitis, or massive necrosis were examined for the presence, composition, and distribution of inflammatory foci. Copper analysis was performed on the specimens. The foci of inflammation and necrosis composed a significant part of the lesion in 15 of the samples. The foci were of two types. One, characteristic of idiopathic chronic active hepatitis, consisted of one or two apoptotic hepatocytes attended by lymphocytes and plasma cells. These foci were found primarily in the vicinity of the portal tracts, not associated with centrolobular copper-laden hepatocytes. The other type of focus was characteristic of copper toxicosis. These foci were larger and composed of debris-filled macrophages, lymphocytes, plasma cells, and scattered neutrophils, and on occasion apoptotic hepatocytes were found at the periphery. These foci were always found around the central vein among the copper-laden hepatocytes. Such foci were found only in dogs with copper concentration > 2,000 parts/million on a dry weight basis. These morphologic studies show that clinical liver disease in WHWTs is caused by more than one etiologic agent. Among 17 WHWTs with clinical liver disease, two had copper toxicosis, five had idiopathic chronic active hepatitis, and 10 had hepatic disease of undetermined type.

Nurses' knowledge of pressure ulcer management in elderly people

The nursing management of pressure ulcers has not been extensively reported in the Hong Kong context. This article reports the results of a survey of 34 Hong Kong registered nurses to determine their knowledge and practices in preventing and treating pressure ulcers in the elderly. The findings indicate that, overall, the nurses had a sound knowledge of the prevention and treatment of pressure ulcers, but that there were inconsistencies in their practices. This situation could be improved if standardized systems for assessing patients at risk of developing pressure ulcers and for grading (staging) these pressure ulcers were used.

Neuropsychological studies of blacks with cerebrovascular disorders: a preliminary investigation

Very few studies have been conducted that examine brain behavior functions in blacks and other ethnic minorities. Recognizing that measures of higher cortical functions have cultural, experiential, and organic determinants, the present investigation was designed to ascertain whether findings reported in neuropsychologic studies of white patients with lateralized cerebral lesions are applicable to groups of black patients with lesions in similar locations. Thirty-seven patients with left (n = 15) and right (n = 22) cerebrovascular lesions were administered the Michigan Neuropsychological Battery (MNB). This battery is comprised of a number of objective standardized measures of higher and lower-level cerebral functions. With one exception, the performance of patients in the brain-injured groups was not systematically different on tests of higher brain functions. As expected, tests of lower-level somatosensory and motor functions showed a pattern of greater impairment on the side of the body contralateral to the lesion. But, in contrast to neuropsychological studies of white patients, a pattern of laterality specific deficits on verbal IQ and performance IQ was not observed. Methodological and theoretical implications of these findings are discussed.

B-lymphocyte activation mediated by anti-immunoglobulin antibody in the absence of protein kinase C

B-cell activation induced by crosslinking of surface immunoglobulin is known to stimulate hydrolysis of phosphatidylinositol to diacylglycerol and inositol trisphosphate. We now provide evidence that alternative pathways of activation may also be recruited during such activation. We utilized depletion of protein kinase C activity to determine whether this enzyme is required under all conditions for anti-immunoglobulin-stimulated B-cell activation. Although anti-immunoglobulin does not induce B-cell proliferation in protein kinase C-depleted cells, it stimulates an earlier event in B-cell activation as reflected by its ability to enhance the expression of major histocompatibility complex-encoded class II molecules. Furthermore, the ribonucleoside 8-mercaptoguanosine restores the ability of anti-immunoglobulin to induce B-cell proliferation in protein kinase C-depleted cells. This restoration is also demonstrated by an enhancement of synthesis of a nuclear protein that we find is increased during B-cell mitogenesis. These results indicate that B-cell activation stimulated by anti-immunoglobulin may recruit pathways in addition to the one dependent on protein kinase C.

Glucocorticoids suppress calcium mobilization and phospholipid hydrolysis in anti-Ig antibody-stimulated B cells

Glucocorticoids have been shown to play a major role in influencing the activation of B lymphocytes. In view of our recent observation that dexamethasone exerts a marked suppressive effect on an early event in B cell activation that is stimulated by anti-Ig antibody, we investigated its activity on other stimuli that induce intracellular events similar to those produced by anti-Ig antibody. Because the intracellular events that occur after B cell stimulation with phorbol myristate acetate and the calcium ionophore A23187 appear to mimic those that occur after B cell stimulation with anti-Ig antibody, we studied whether the cellular responses elicited by these activation stimuli are affected in a similar fashion by dexamethasone. Whereas anti-Ig antibody-stimulated entry of G0 B cells to the G1 and S phase of the cell cycle was markedly suppressed by dexamethasone, phorbol myristate acetate/A23187 stimulation of these events was resistant to dexamethasone. Our finding that anti-Ig-induced cross-linking of B cell surface Ig, as measured by surface Ig capping, was not inhibited by dexamethasone suggested that corticosteroids inhibit anti-Ig-induced B cell proliferation at a step distal to membrane Ig cross-linking and proximal to phosphatidylinositol bisphosphate hydrolysis. This hypothesis is supported by experiments presented in this manuscript which demonstrate that dexamethasone inhibits anti-Ig-stimulated phosphatidylinositol bisphosphate hydrolysis. We also found that dexamethasone markedly inhibited anti-Ig antibody-stimulated increases in intracellular ionized calcium concentrations. This dexamethasone-mediated suppression is time-dependent as it is not seen when B cells are cultured with dexamethasone for less than 6 hr. Our data suggest that the immunomodulatory activity of glucocorticoids is exerted by binding to its nuclear receptor, thereby preventing the generation of second messengers required for cell activation after agonist-receptor interaction.

Glucocorticoids suppress calcium mobilization and phospholipid hydrolysis in anti-Ig antibody-stimulated B cells

Glucocorticoids have been shown to play a major role in influencing the activation of B lymphocytes. In view of our recent observation that dexamethasone exerts a marked suppressive effect on an early event in B cell activation that is stimulated by anti-Ig antibody, we investigated its activity on other stimuli that induce intracellular events similar to those produced by anti-Ig antibody. Because the intracellular events that occur after B cell stimulation with phorbol myristate acetate and the calcium ionophore A23187 appear to mimic those that occur after B cell stimulation with anti-Ig antibody, we studied whether the cellular responses elicited by these activation stimuli are affected in a similar fashion by dexamethasone. Whereas anti-Ig antibody-stimulated entry of G0 B cells to the G1 and S phase of the cell cycle was markedly suppressed by dexamethasone, phorbol myristate acetate/A23187 stimulation of these events was resistant to dexamethasone. Our finding that anti-Ig-induced cross-linking of B cell surface Ig, as measured by surface Ig capping, was not inhibited by dexamethasone suggested that corticosteroids inhibit anti-Ig-induced B cell proliferation at a step distal to membrane Ig cross-linking and proximal to phosphatidylinositol bisphosphate hydrolysis. This hypothesis is supported by experiments presented in this manuscript which demonstrate that dexamethasone inhibits anti-Ig-stimulated phosphatidylinositol bisphosphate hydrolysis. We also found that dexamethasone markedly inhibited anti-Ig antibody-stimulated increases in intracellular ionized calcium concentrations. This dexamethasone-mediated suppression is time-dependent as it is not seen when B cells are cultured with dexamethasone for less than 6 hr. Our data suggest that the immunomodulatory activity of glucocorticoids is exerted by binding to its nuclear receptor, thereby preventing the generation of second messengers required for cell activation after agonist-receptor interaction.