Label-Free In Situ Chemical Characterization of Amyloid Plaques in Human Brain Tissues

The accumulation of amyloid plaques and increased brain redox burdens are neuropathological hallmarks of Alzheimer's disease. Altered metabolism of essential biometals is another feature of Alzheimer's, with amyloid plaques representing sites of disturbed metal homeostasis. Despite these observations, metal-targeting disease treatments have not been therapeutically effective to date. A better understanding of amyloid plaque composition and the role of the metals associated with them is critical. To establish this knowledge, the ability to resolve chemical variations at nanometer length scales relevant to biology is essential. Here, we present a methodology for the label-free, nanoscale chemical characterization of amyloid plaques within human Alzheimer's disease tissue using synchrotron X-ray spectromicroscopy. Our approach exploits a C-H carbon absorption feature, consistent with the presence of lipids, to visualize amyloid plaques selectively against the tissue background, allowing chemical analysis to be performed without the addition of amyloid dyes that alter the native sample chemistry. Using this approach, we show that amyloid plaques contain elevated levels of calcium, carbonates, and iron compared to the surrounding brain tissue. Chemical analysis of iron within plaques revealed the presence of chemically reduced, low-oxidation-state phases, including ferromagnetic metallic iron. The zero-oxidation state of ferromagnetic iron determines its high chemical reactivity and so may contribute to the redox burden in the Alzheimer's brain and thus drive neurodegeneration. Ferromagnetic metallic iron has no established physiological function in the brain and may represent a target for therapies designed to lower redox burdens in Alzheimer's disease. Additionally, ferromagnetic metallic iron has magnetic properties that are distinct from the iron oxide forms predominant in tissue, which might be exploitable for the in vivo detection of amyloid pathologies using magnetically sensitive imaging. We anticipate that this label-free X-ray imaging approach will provide further insights into the chemical composition of amyloid plaques, facilitating better understanding of how plaques influence the course of Alzheimer's disease.

Optical Microscopy Using the Faraday Effect Reveals in Situ Magnetization Dynamics of Magnetic Nanoparticles in Biological Samples

The study of exogenous and endogenous nanoscale magnetic material in biology is important for developing biomedical nanotechnology as well as for understanding fundamental biological processes such as iron metabolism and biomineralization. Here, we exploit the magneto-optical Faraday effect to probe intracellular magnetic properties and perform magnetic imaging, revealing the location-specific magnetization dynamics of exogenous magnetic nanoparticles within cells. The opportunities enabled by this method are shown in the context of magnetic hyperthermia; an effect where local heating is generated in magnetic nanoparticles exposed to high-frequency AC magnetic fields. Magnetic hyperthermia has the potential to be used as a cellular-level thermotherapy for cancer, as well as for other biomedical applications that target heat-sensitive cellular function. However, previous experiments have suggested that the cellular environment modifies the magnetization dynamics of nanoparticles, thus dramatically altering their heating efficiency. By combining magneto-optical and fluorescence measurements, we demonstrate a form of biological microscopy that we used here to study the magnetization dynamics of nanoparticles in situ, in both histological samples and living cancer cells. Correlative magnetic and fluorescence imaging identified aggregated magnetic nanoparticles colocalized with cellular lysosomes. Nanoparticles aggregated within these lysosomes displayed reduced AC magnetic coercivity compared to the same particles measured in an aqueous suspension or aggregated in other areas of the cells. Such measurements reveal the power of this approach, enabling investigations of how cellular location, nanoparticle aggregation, and interparticle magnetic interactions affect the magnetization dynamics and consequently the heating response of nanoparticles in the biological milieu.

Incidental Colonic Masses and Cytomegalovirus (CMV) Infection in a Treatment- Naïve Chronic Lymphocytic Leukemia Patient without GI symptoms

Introduction/Objective

Gastrointestinal (GI) involvement by leukemia ranges from 5.7 to 13 % with very few published reports describing infiltration of the GI tract by chronic lymphocytic leukemia (CLL). GI bleeding, abdominal pain, and obstruction have been described as presenting symptoms of GI involvement. Yet, discrete lesions are rare. Infection is a common complication in patients with CLL. In untreated patients, these infections are typically by encapsulated bacteria involving the respiratory tract and associated with hypogammaglobulinemia. Viral infections often happen after therapy. This report presents a patient with a history of treatment- naïve CLL and HSV who presented for colostomy reversal and was incidentally found to have two partially obstructing colonic masses, as well as cytomegalovirus (CMV) infection.

Methods/Case Report

This is a 78-years-old female with treatment-naïve CLL and past medical history of hypertension, atrial fibrillation, diverting colostomy secondary to chronic perineal HSV-2 ulcer and recent perirectal abscess. She presented for colostomy reversal in the absence of any reported GI symptoms at that time. Labs showed leukocytosis; WBCs count of 25 K/MM3, anemia and neutropenia. Endoscopic studies incidentally discovered two partially obstructing masses in the ascending and transverse colon that were biopsied. A right hemicolectomy and colostomy closure were followed, and the patient was discharged on valganciclovir.

Results (if a Case Study enter NA)

Histopathological examination demonstrated mucosal ulceration with viral cytopathic changes and positive CMV IHC stain. In addition, a dense atypical, small sized lymphoid cell infiltrate with no sheets of large cells or confluent necrosis were identified. Flowcytometry and IHC stains showed aberrant CD5+ B cells with CD23 co-expression consistent with the patient’s history of CLL.

Conclusion

The case describes the unique presentation of a patient with treatment- naïve CLL without any GI symptoms, yet was incidentally found to have colonic involvement by CLL forming discrete colonic masses as well as CMV and HSV infections. Since she is untreated, her infections (HSV and CMV) are likely secondary to being immunocompromised by CLL and neutropenia. In conclusion, although rare, GI involvement by CLL should be considered in treatment naïve CLL patient’s and concomitant infections should be evaluated.

Biogenic metallic elements in the human brain?

The chemistry of copper and iron plays a critical role in normal brain function. A variety of enzymes and proteins containing positively charged Cu+, Cu2+, Fe2+, and Fe3+ control key processes, catalyzing oxidative metabolism and neurotransmitter and neuropeptide production. Here, we report the discovery of elemental (zero-oxidation state) metallic Cu0 accompanying ferromagnetic elemental Fe0 in the human brain. These nanoscale biometal deposits were identified within amyloid plaque cores isolated from Alzheimer's disease subjects, using synchrotron x-ray spectromicroscopy. The surfaces of nanodeposits of metallic copper and iron are highly reactive, with distinctly different chemical and magnetic properties from their predominant oxide counterparts. The discovery of metals in their elemental form in the brain raises new questions regarding their generation and their role in neurochemistry, neurobiology, and the etiology of neurodegenerative disease.

Nanoscale chemical speciation of β-amyloid/iron aggregates using soft X-ray spectromicroscopy

Nanoscale resolution X-ray spectromicroscopy shows the co-incubation of β-amyloid (Aβ) and iron(iii) to result in aggregate structures displaying nanoscale heterogeneity in Aβ and iron chemistry, including the formation of potentially cytotoxic Fe⁰.

Analysis of neuronal iron deposits in Parkinson's disease brain tissue by synchrotron x-ray spectromicroscopy

BACKGROUND

Neuromelanin-pigmented neurons, which are highly susceptible to neurodegeneration in the Parkinson's disease substantia nigra, harbour elevated iron levels in the diseased state. Whilst it is widely believed that neuronal iron is stored in an inert, ferric form, perturbations to normal metal homeostasis could potentially generate more reactive forms of iron capable of stimulating toxicity and cell death. However, non-disruptive analysis of brain metals is inherently challenging, since use of stains or chemical fixatives, for example, can significantly influence metal ion distributions and/or concentrations in tissues.

AIMS

The aim of this study was to apply synchrotron soft x-ray spectromicroscopy to the characterisation of iron deposits and their local environment within neuromelanin-containing neurons of Parkinson's disease substantia nigra.

METHODS

Soft x-ray spectromicroscopy was applied in the form of Scanning Transmission X-ray Microscopy (STXM) to analyse resin-embedded tissue, without requirement for chemically disruptive processing or staining. Measurements were performed at the oxygen and iron K-edges in order to characterise both organic and inorganic components of anatomical tissue using a single label-free method.

RESULTS

STXM revealed evidence for mixed oxidation states of neuronal iron deposits associated with neuromelanin clusters in Parkinson's disease substantia nigra. The excellent sensitivity, specificity and spatial resolution of these STXM measurements showed that the iron oxidation state varies across sub-micron length scales.

CONCLUSIONS

The label-free STXM approach is highly suited to characterising the distributions of both inorganic and organic components of anatomical tissue, and provides a proof-of-concept for investigating trace metal speciation within Parkinson's disease neuromelanin-containing neurons.

Label-Free Nanoimaging of Neuromelanin in the Brain by Soft X-ray Spectromicroscopy

A hallmark of Parkinson's disease is the death of neuromelanin-pigmented neurons, but the role of neuromelanin is unclear. The in situ characterization of neuromelanin remains dependent on detectable pigmentation, rather than direct quantification of neuromelanin. We show that direct, label-free nanoscale visualization of neuromelanin and associated metal ions in human brain tissue can be achieved using synchrotron scanning transmission x-ray microscopy (STXM), through a characteristic feature in the neuromelanin x-ray absorption spectrum at 287.4 eV that is also present in iron-free and iron-laden synthetic neuromelanin. This is confirmed in consecutive brain sections by correlating STXM neuromelanin imaging with silver nitrate-stained neuromelanin. Analysis suggests that the 1s-σ* (C-S) transition in benzothiazine groups accounts for this feature. This method illustrates the wider potential of STXM as a label-free spectromicroscopy technique applicable to both organic and inorganic materials.

Iron stored in ferritin is chemically reduced in the presence of aggregating Aβ(1-42)

Atypical low-oxidation-state iron phases in Alzheimer's disease (AD) pathology are implicated in disease pathogenesis, as they may promote elevated redox activity and convey toxicity. However, the origin of low-oxidation-state iron and the pathways responsible for its formation and evolution remain unresolved. Here we investigate the interaction of the AD peptide β-amyloid (Aβ) with the iron storage protein ferritin, to establish whether interactions between these two species are a potential source of low-oxidation-state iron in AD. Using X-ray spectromicroscopy and electron microscopy we found that the co-aggregation of Aβ and ferritin resulted in the conversion of ferritin's inert ferric core into more reactive low-oxidation-states. Such findings strongly implicate Aβ in the altered iron handling and increased oxidative stress observed in AD pathogenesis. These amyloid-associated iron phases have biomarker potential to assist with disease diagnosis and staging, and may act as targets for therapies designed to lower oxidative stress in AD tissue.

Metal Ion Binding to the Amyloid β Monomer Studied by Native Top-Down FTICR Mass Spectrometry

Native top-down mass spectrometry is a fast, robust biophysical technique that can provide molecular-scale information on the interaction between proteins or peptides and ligands, including metal cations. Here we have analyzed complexes of the full-length amyloid β (1-42) monomer with a range of (patho)physiologically relevant metal cations using native Fourier transform ion cyclotron resonance mass spectrometry and three different fragmentation methods-collision-induced dissociation, electron capture dissociation, and infrared multiphoton dissociation-all yielding consistent results. Amyloid β is of particular interest as its oligomerization and aggregation are major events in the etiology of Alzheimer's disease, and it is known that interactions between the peptide and bioavailable metal cations have the potential to significantly damage neurons. Those metals which exhibited the strongest binding to the peptide (Cu²⁺, Co²⁺, Ni²⁺) all shared a very similar binding region containing two of the histidine residues near the N-terminus (His6, His13). Notably, Fe³⁺ bound to the peptide only when stabilized toward hydrolysis, aggregation, and precipitation by a chelating ligand, binding in the region between Ser8 and Gly25. We also identified two additional binding regions near the flexible, hydrophobic C-terminus, where other metals (Mg²⁺, Ca²⁺, Mn²⁺, Na⁺, and K⁺) bound more weakly-one centered on Leu34, and one on Gly38. Unexpectedly, collisional activation of the complex formed between the peptide and [Co^III(NH₃)₆]³⁺ induced gas-phase reduction of the metal to Co^II, allowing the peptide to fragment via radical-based dissociation pathways. This work demonstrates how native mass spectrometry can provide new insights into the interactions between amyloid β and metal cations.

Nanoscale synchrotron X-ray speciation of iron and calcium compounds in amyloid plaque cores from Alzheimer's disease subjects

Altered metabolism of biometals in the brain is a key feature of Alzheimer's disease, and biometal interactions with amyloid-β are linked to amyloid plaque formation. Iron-rich aggregates, including evidence for the mixed-valence iron oxide magnetite, are associated with amyloid plaques. To test the hypothesis that increased chemical reduction of iron, as observed in vitro in the presence of aggregating amyloid-β, may occur at sites of amyloid plaque formation in the human brain, the nanoscale distribution and physicochemical states of biometals, particularly iron, were characterised in isolated amyloid plaque cores from human Alzheimer's disease cases using synchrotron X-ray spectromicroscopy. In situ X-ray magnetic circular dichroism revealed the presence of magnetite: a finding supported by ptychographic observation of an iron oxide crystal with the morphology of biogenic magnetite. The exceptional sensitivity and specificity of X-ray spectromicroscopy, combining chemical and magnetic probes, allowed enhanced differentiation of the iron oxides phases present. This facilitated the discovery and speciation of ferrous-rich phases and lower oxidation state phases resembling zero-valent iron as well as magnetite. Sequestered calcium was discovered in two distinct mineral forms suggesting a dynamic process of amyloid plaque calcification in vivo. The range of iron oxidation states present and the direct observation of biogenic magnetite provide unparalleled support for the hypothesis that chemical reduction of iron arises in conjunction with the formation of amyloid plaques. These new findings raise challenging questions about the relative impacts of amyloid-β aggregation, plaque formation, and disrupted metal homeostasis on the oxidative burden observed in Alzheimer's disease.

Self-Awareness and “Introspective” Private Speech in 6-Year-Old Children

It has been suggested recently that self-awareness is cognitively mediated by inner speech and that this hypothesis could be tested by using the private speech paradigm. This paper describes a study in which the creation of a state of self-awareness was attempted in children to test the viability of a research strategy based on private speech and used to explore the hypothesis of a link between self-awareness and inner speech, and to test directly this hypothesis by comparing the incidence of private speech in self-aware and control conditions. 32 children were asked to evaluate the attractiveness of pictures when in front of a mirror (a widely used self-focusing stimulus) and with no mirror. Reliably more favorable ratings of the images were predicted presuming intensification of affects in self-awareness. Private speech was recorded, with the prediction of a more important incidence of “introspective” self-verbalizations (for example, “Wow! I really like this picture!”) in the self-aware condition. None of these outcomes were obtained. Results are discussed in terms of previous attempts to manipulate self-awareness in children. It is suggested that the private speech paradigm does not appear to be a promising strategy when inner speech and self-awareness are considered.

The presence of biofilm structures in atherosclerotic plaques of arteries from legs amputated as a complication of diabetic foot ulcers

OBJECTIVE

Atherosclerosis, rather than microcirculatory impairment caused by endothelial cell dysfunction, is the main driver of circulatory compromise in patients with diabetic limbs. The presence of atherosclerotic plaque at the trifurcation is a significant contributor to amputation of diabetic legs. The presence of bacteria and other microorganisms in atherosclerotic plaque has long been known, however, the cause of chronic inflammation and the role of bacteria/viruses in atherosclerosis have not been studied in detail. The objective of this study was to clarify the cause of the chronic inflammation within atherosclerotic plaques, and determine if any bacteria and/or viruses are involved in the inflammatory pathway.

METHOD

This study uses fluorescence microscopy and fluorescence in-situ hybridisation (FISH) to identify components of biofilm in atherosclerotic arteries. These tools are also used to identify individual bacteria, and determine the architectural spatial location within the atherosclerotic plaque where the bacteria can be found.

RESULTS

The results indicate that the presence of biofilms in grossly involved arteries may be an important factor in chronic inflammatory pathways of atherosclerotic progression, in the amputated limbs of patients with diabetic foot ulcers and vascular disease.

CONCLUSION

While the presence of bacterial biofilm structures in atherosclerotic plaque does not prove that biofilm is the proximate cause of atherosclerosis, it could contribute to the persistent inflammation associated with it. Second, the synergistic relationship between the atherosclerotic infection and the diabetic foot ulcer may ultimately contribute to higher amputation rates in diabetics.

DECLARATION OF INTEREST

RAW and RDW have equity interest in PathoGenius, a clinical laboratory using DNA to identify microbes.

Ferrous iron formation following the co-aggregation of ferric iron and the Alzheimer's disease peptide β-amyloid (1-42)

For decades, a link between increased levels of iron and areas of Alzheimer's disease (AD) pathology has been recognized, including AD lesions comprised of the peptide β-amyloid (Aβ). Despite many observations of this association, the relationship between Aβ and iron is poorly understood. Using X-ray microspectroscopy, X-ray absorption spectroscopy, electron microscopy and spectrophotometric iron(II) quantification techniques, we examine the interaction between Aβ(1–42) and synthetic iron(III), reminiscent of ferric iron stores in the brain. We report Aβ to be capable of accumulating iron(III) within amyloid aggregates, with this process resulting in Aβ-mediated reduction of iron(III) to a redox-active iron(II) phase. Additionally, we show that the presence of aluminium increases the reductive capacity of Aβ, enabling the redox cycling of the iron. These results demonstrate the ability of Aβ to accumulate iron, offering an explanation for previously observed local increases in iron concentration associated with AD lesions. Furthermore, the ability of iron to form redox-active iron phases from ferric precursors provides an origin both for the redox-active iron previously witnessed in AD tissue, and the increased levels of oxidative stress characteristic of AD. These interactions between Aβ and iron deliver valuable insights into the process of AD progression, which may ultimately provide targets for disease therapies.

Evidence of redox-active iron formation following aggregation of ferrihydrite and the Alzheimer's disease peptide β-amyloid

Recent work has demonstrated increased levels of redox-active iron biominerals in Alzheimer's disease (AD) tissue. However, the origin, nature, and role of iron in AD pathology remains unclear. Using X-ray absorption, X-ray microspectroscopy, and electron microscopy techniques, we examined interactions between the AD peptide β-amyloid (Aβ) and ferrihydrite, which is the ferric form taken when iron is stored in humans. We report that Aβ is capable of reducing ferrihydrite to a pure iron(II) mineral where antiferromagnetically ordered Fe(2+) cations occupy two nonequivalent crystal symmetry sites. Examination of these iron(II) phases following air exposure revealed a material consistent with the iron(II)-rich mineral magnetite. These results demonstrate the capability of Aβ to induce the redox-active biominerals reported in AD tissue from natural iron precursors. Such interactions between Aβ and ferrihydrite shed light upon the processes of AD pathogenesis, while providing potential targets for future therapies.

Effects of chronic iron deficiency anaemia on myoglobin content, enzyme activity, and capillary density in the human skeletal muscle

The influence of chronic iron deficiency anaemia on myoglobin content, maximal enzyme activities and capillarization in the human skeletal muscle was investigated. Muscle samples from musculus vastus lateralis were screened in an Indonesian population. The causes of iron deficiency were chronic intestinal bleeding or repeated pregnancy combined with low iron intake. The maximal activities of iron-dependent and non-iron-dependent glycolytic and oxidative enzymes as well as myoglobin showed similar values in the iron-deficient group and the matched control group. The activities of the oxidative enzymes in both the iron-deficient group and the controls were lower, however, compared even to untrained Swedish subjects. The capillary density was essentially within a normal range in both groups. It is concluded that chronic iron deficiency anaemia of a moderate or severe degree, with Hb concentrations of about 80-100 g.1(-1), does not cause an impaired biochemical function of the human skeletal muscle.

The NCI pediatric central institutional review board (PedCIRB) initiative: Progress and impact

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NCI has developed a central IRB (PedCIRB) to review NCI-sponsored pediatric clinical trials conducted by the Children's Oncology Group (COG). COG comprises ∼200 U.S. medical institutions and protocol activation traditionally requires separate protocol review by each local IRB (LIRB) and, subsequently, a review of each protocol amendment and significant adverse event. The PedCIRB model seeks to increase patient protection by improving the expertise of protocol reviewers and making their review available to all PedCIRB participating institutions. The PedCIRB consists of experts in pediatric oncology, pediatric medicine, nursing, pharmacy, bioethics, biostatistics, as well as patient advocates and childhood cancer survivors. The PedCIRB model also eliminates redundant reviews, reduces administrative burdens on local COG investigators and LIRBs, and can accelerate the pace of local protocol activation, thus increasing the availability of clinical trials to children with cancer. The PedCIRB conducts a full board protocol review that is available via a confidential website to participating LIRBs. LIRBs can choose to perform a facilitated review, using PedCIRB materials, that focuses on local concerns, rather than a full LIRB protocol review. If the LIRB accepts the PedCIRB review, the PedCIRB becomes the IRB of record for that protocol and takes responsibility for the review of subsequent protocol amendments, adverse events and continuing reviews. Since starting in November 2004, the PedCIRB has reviewed 59 protocols. Initial reviews resulted in 44 approvals pending modification and 15 protocols being tabled for further information. The time from protocol submission to final approval by the PedCIRB has ranged from 3 to 28 weeks with an average time of 16.9 weeks during year one and 12.7 weeks during year two of the project. As of November 2006, 117 of a possible 197 U.S. COG institutions (59%) have signed on to the PedCIRB initiative and 70% of the participating institutions have conducted facilitated reviews (total 750) for the 30 protocols available on the PedCIRB website. The PedCIRB's influence on protocol development and patient accrual timelines will be discussed.

No significant financial relationships to disclose.

Use of the Internet to optimize self-management of type 1 diabetes: preliminary experience with DiasNet

Six patients with type 1 diabetes participated in a pilot trial. Their median age was 36 years (range 29-61) and the median duration of diabetes was 10 years (range 3-29). They were asked to enter, from their home or work PC, blood glucose values, insulin doses and a food diary. From the data entered, a computer model generated a simulation of the blood glucose concentration for the data collection period. It could then suggest alternative insulin doses (or regimes), or meal sizes, to reduce the risk of hypo- and hyperglycaemia. During a six-month study, patients entered a median of five sets of data (range two to eight). Feedback from participants revealed that while the system was helpful, difficulties with data entry hindered its use. Information gained from this exercise is shaping further development of the system.

Depression, attention, and time estimation

Depression is known to affect several cognitive functions, but little is known about the effect of this neuropsychological disorder on timing tasks. In the present experiment, 15 depressed and 20 non-depressed participants, classified on the basis of the Beck Depression Inventory, were tested on attentional and on temporal processing tasks. On the Continuous Performance Test, depressed participants made more omissions, but not more erroneous responses, than non-depressed participants. As well, discrimination of relatively long intervals (1120 vs 1280 ms) was poorer for the depressed group, which was not the case for discrimination of brief durations (80 vs 120 ms, and 450 vs 550 ms). Finally, there was a significant difference between groups regarding the variability of 1- or 10-s interval productions made with continuous series of finger taps. The attentional requirements of long-interval processing seems to be a critical factor in depression-induced deficits of temporal processing.

Fine motor dexterity is correlated to social functioning in schizophrenia

OBJECTIVE

To identify neuropsychological domains, including fine motor dexterity, that are related to social functioning in schizophrenia.

METHOD

Thirty-six DSM-IV schizophrenic subjects were assessed using the Purdue Pegboard test, the Modified Wisconsin Card Sorting test, the Tower of London, Schwartz' Reaction Time and Wechsler's Associate Learning and Digit Span tests. Social functioning was measured by the Social and Occupational Functional Assessment Scale.

RESULTS

Univariate regression analyses showed that the Purdue Pegboard, the Modified Card Sorting test, the Tower of London and Wechsler's Associate Learning subtest were significantly linked to social functioning. The best fitting multivariate model to explain social functioning included fine motor dexterity and executive functioning.

CONCLUSION

Various neuropsychological measures correlated to social functioning, the correlation involving fine motor dexterity being the strongest one. Future studies of the prediction of social functioning in schizophrenia should include fine motor dexterity.

A pilot neuropsychological study of Kraepelinian and non-Kraepelinian schizophrenia

OBJECTIVE

This is the first study to report a direct comparison of neuropsychological performance in Kraepelinian vs. non-Kraepelinian schizophrenia (SZ).

METHODS

17 Kraepelinian and 19 non-Kraepelinian subjects were assessed on a neuropsychological battery including the Purdue Pegboard, Schwartz' Reaction Time task, the Modified Card Sorting Test, the Wechsler's Associate Learning Test and the Digit Span.

RESULTS

Kraepelinian schizophrenia was characterized by more impaired performance on the Purdue Pegboard and the Card Sorting test. These differences remained significant when introducing, as covariates, the type of neuroleptic used, the use of anticholinergic medication, age and gender. Differences on the Reaction Time, the Associate Learning and the Digit Span tasks did not reach statistical significance.

CONCLUSIONS

These results suggest that Kraepelinian schizophrenia is characterized by impaired performance on fine motor dexterity and executive functioning. These results further add to the evidence for the validity of the distinction between Kraepelinian and non-Kraepelinian schizophrenia as a strategy to better understand the factors influencing severity and/or outcome in schizophrenia.

[Schizophrenia and performance on the Wisconsin Card Sorting Test (WCST): deficits and rehabilitation]

In recent years, there has been a sustained interest in the so-called "frontal hypothesis" of schizophrenia: the idea that clinical symptoms and cognitive deficits characteristic of schizophrenia might be explained by defective function of the frontal lobes. Several studies have attempted to test this hypothesis by examining the performance of schizophrenic subjects on the Wisconsin Card Sorting Test (WCST), a neuropsychological evaluation widely believed to reflect the functional capacity of frontal lobes. A typical finding is that schizophrenic patients demonstrate a tendency to perseverate in producing an inappropriate response in spite of negative feedback. This perseverative tendency resembles the perseveration often seen in patients with frontal brain damage. This article proposes a critical examination of the available evidence linking frontal deficits with schizophrenia via the WCST. As we will show, in most of these studies, only a relatively small number of the available measures on the WCST are made, and consequently many interesting cognitive capacities in schizophrenic subjects have not been adequately examined with this test. These "non-classical" measures will be described and critically examined with respect to their pertinence for further work on schizophrenic subjects. Of particular interest are the "failure to maintain set", which measures cognitive instability, "conceptual responses", which can indicate a certain conceptual capacity even in subjects who show perseveration, and "learning to learn", which can demonstrate a capacity to profit from experience on the test. A second objective will be to critically examine the evidence concerning the capacity of schizophrenic patients to improve their performance on the WCST. To the extent that performance on the WCST reflects the functional level of cognitive capacities important for everyday life, any capacity in schizophrenic patients to improve their performance could have important implications for therapeutic intervention and re-education.

The application of non-combinatorial chemistry to lead discovery

Non-combinatorial chemistry is a powerful technology for the synthesis of large numbers of compounds, with complete control over the properties of those compounds. We have developed a Library Creation, Registration and Automation system (LiCRA), which harnesses an efficient non-combinatorial chemistry design and synthesis engine, together with high-throughput automated purification. This LiCRA system also operates in a closed loop mode for hit-to-lead optimization, and contains an integrated IT system that controls and facilitates all aspects of the operation from design to registration. Quality has been our watchword, from the quality of compound design through to the quality of the products.

Prospective evaluation of an outpatient heart failure management program

BACKGROUND

Although considerable effort has been devoted to the follow-up of hospitalized patients, the effectiveness and process of heart failure outpatient management have not been well demonstrated.

METHODS AND RESULTS

All new patients referred to the program from April 1997 to September 1998 were followed and managed by comprehensive strategies including preemptive hospitalization. Quality of life (QOL) and patients' self-care adherence behaviors were measured at baseline, 3 months, and 6 months. Clinical outcomes were compared for the 6 months before and 6 months after referral. A total of 108 patients were recruited. Patients' self-care knowledge score was improved over time (difference score = 0.9, P <.01). The proportion of patients weighing themselves daily increased by 24% (P =.02). The proportion of patients with New York Heart Association (NYHA) class III to IV was 67.6% at baseline and 49.1% at 6 months (P =.01). Compared with 6 months before referral, the program intervention was accompanied by a 52% reduction in the risk of hospitalization for cardiovascular causes (56.1% v 27.2%, P <.001) and a 72% reduction in emergency room visits (53.6% v 14.5%, P <.01). The total hospital admissions for cardiovascular causes decreased by 59% from 94 to 39; the total emergency room visits decreased by 77% from 83 to 19. The patients' QOL was improved over time with a change score of 11.2 (P <.001) at 3 months and 10.7 (P <.001) at 6 months.

CONCLUSION

Our study shows the effectiveness of this heart failure outpatient management program.

Performance of patients with schizophrenia on the Wisconsin Card Sorting Test (WCST)

OBJECTIVE

To directly compare the performance of patients with schizophrenia and control subjects on the Wisconsin Card Sorting Test (WCST). Specifically, we sought to verify if there are significant differences on the "classical" WCST measurements (perseverative errors and number of categories), as well as on more rarely reported scores, and assess the extent to which patients with schizophrenia can improve their performance with card-by-card instructions and continuous verbal reinforcement.

DESIGN

Prospective cross-sectional study.

SETTING

Psychiatry department in a university-affiliated hospital.

PARTICIPANTS

30 patients with schizophrenia, diagnosed according to DSM-IV criteria, and 30 control subjects, matched to patients according to age and education.

INTERVENTION

The WCST was administered according to the criteria of Heaton, and a subgroup of the patients with schizophrenia was given a retest after an explanation of the WCST and verbal reinforcements.

RESULTS

Patients with schizophrenia succeeded on fewer categories (t = 23.3, p < 0.001), committed more perseverative errors (t = 15.6, p < 0.001), made more perseverative responses (t = 14.6, p < 0.001), needed more trials to succeed at the first category (t = 9.2, p < 0.003) and gave significantly lower conceptual level responses (t = 14.1, p < 0.001) than the controls. However, on retest, patients with schizophrenia committed significantly fewer perseverative errors (t = 5.1, p < 0.001) and showed higher conceptual level responses (t = -3.45, p < 0.003).

CONCLUSION

Consistent with a hypothesis of frontal dysfunction in schizophrenia, patients with schizophrenia tend to show a perseverative deficit; however, some are able to partially overcome this deficit when given verbal reinforcement.

Reducing hospital inpatient length of stay for patients with diabetes

AIMS

To ascertain the effect of routine review by a diabetes nurse advisor on length of stay for medical and surgical inpatients with diabetes.

METHODS

Inpatients with diabetes were identified prospectively from January 1997 until December 1998 (792 in 1997 and 819 in 1998). A new post of diabetes nurse advisor was introduced in January 1998 to optimize diabetes management. Length of stay was calculated retrospectively from hospital computer records.

RESULTS

Median length of stay in 1997 was 11 days in medicine and 8 days in surgery. In 1998, the nurse advisor made 1936 visits to 819 patients; median length of stay fell to 8 days in medicine and 5 days in surgery (P < 0.001). Bed occupancy by patients with diabetes fell from 6.8 to 4.0%. Mean length of stay across the hospital remained unchanged.

CONCLUSIONS

The introduction of a ward-based diabetes nurse advisor was associated with significant reductions in length of stay in inpatients with diabetes. Since this study was not a randomized study, other factors may have contributed to this change. However, the consistency of the reduction across specialities suggests the post itself had an important effect.

Driving and insulin--consensus, conflict or confusion?

AIMS

All drivers requiring insulin treatment must be able to demonstrate satisfactory diabetic control and recognition of hypoglycaemic symptoms before being allowed to drive a motor vehicle. Clinicians have a duty to discuss fitness to drive with their patients. However, is the advice given consistent and in line with the regulations published by the Driver and Vehicle Licensing Authority (DVLA)?

METHODS

Six 'real-life' case scenarios were posted to clinicians (consultant diabetologists, specialist registrars and diabetes specialist nurses) within Wessex, UK. The identical cases were also sent to the DVLA for their comments.

RESULTS

Sixty-six doctors (36 consultants) and 70 diabetes specialist nurses were contacted by postal questionnaire of which replies were received from 17 consultants (47%), 17 specialist registrars (57%) and 39 diabetes specialist nurses (56%). Although there was general agreement in cases of hypoglycaemia unawareness, there was disagreement where patients had or were at risk of unstable control albeit for a short time.

CONCLUSIONS

Patients treated with insulin may receive conflicting information concerning their ability to drive.

[Cognitive inhibition and psychopathology: toward a less simplistic conceptualization]

"Cognitive inhibition" is a concept that has found a firm place in the interpretation of performance by normal subjects on tasks involving adherence to a plan and suppression of incorrect responses to distractors. The presence of "negative priming" is the classical indicator of cognitive inhibition. Negative priming occurs when, in a sequence of stimuli each of which is composed of a target and a distractor, the distractor of the first stimulus becomes the target of the second stimulus: reaction time to the second stimulus is slowed because of the inhibition applied to the distractor of the first stimulus. The concept has been extended to the interpretation of pathological behavior and symptoms. Pathological subjects have been found to show deficient negative priming. Thus, negative ideation in depression as well as intrusive paranoid associations in schizophrenia have been related to a deficit in the capacity to inhibit inappropriate representations. In this paper, we briefly review some of the experimental evidence from normal subjects that has contributed to the acceptance of cognitive inhibition as a key process in the control of normal cognition, as well as more recent evidence that has led to a revision of the concept. Negative priming in normal subjects has been found to be dependent upon characteristics of the experimental situation as perceived by the subject. In particular, priming is observed when the subject anticipates difficulty in determining the response and proceeds with caution. Thus, inhibition is not an automatic "brake" applied to irrelevant material, but rather the product of strategic considerations within the experimental situation. This revision of the cognitive inhibition hypothesis leads to a re-interpretation of the apparently deficient cognitive inhibition seen in depressed or schizophrenic subjects. According to this more recent interpretation, deficient cognitive inhibition in pathological subjects can be seen as a less adaptive strategic adjustment to the task. The pathology seems to touch higher-level executive functions rather than a deficient inhibitory "brake". In depressed subjects, abnormal performance in selective attention tasks could be related to the underlying pathology in two ways: some depressed subjects show a marked lack of energy and a psychomotor slowing: these subjects do not exhibit normal negative priming, probably because of a reduction of cognitive resources. Other depressed subjects show abnormal performance as reflected by negative priming greater than normal: this result could be related to an exaggerated tendency to verify a correct response. Schizophrenic subjects show a lack of negative priming that seems most plausibly to be related to an ineffectual integration of the experimental instructions concerning both speed and accuracy in the response. This re-interpretation of the cognitive deficiency in pathological patients provides a better fit with recent experimental results from normal subjects, and with cognitive deficits measured in pathological subjects.

[Deficit in suppression of interference in visual information processing by schizophrenic subjects]

Although many studies have indicated information processing deficits in schizophrenic patients, the precise nature and underlying causes of these deficits remain largely uncertain. One prominent hypothesis is that these patients show insufficient attentional inhibition. This deficit to inhibition has been linked to certain cognitive disorders in schizophrenic patients, including attention deficits, as well as to some clinical symptoms, especially those involving delusional thought, hallucinations,and poor contact with reality. The hypothesis of deficient attentional inhibition, although attractive in some ways, is difficult to work with, because it is not easy to directly measure "attentional inhibition". Several studies involving normal subjects have linked attentional inhibition with performance on a task demanding the suppression of distracting information: the presumption is that efficient attentional inhibition will permit rapid responses because the distracting information will be quickly suppressed, allowing undistracted processing of the target information. The present study measures schizophrenic patients' performance on a task demanding suppression of rapidly-presented visual information. An important methodological feature of this study is that performance is measured in terms of "percent correct responses" rather than the reaction time measures typically used in tasks demanding distractor suppression, such as Stroop-like selective attention tasks. Since reaction times are not considered, the results cannot be interpreted in terms of deficient response organization and execution. Schizophrenic (18) and normal (18) subjects underwent trials in which a visual target was the second of two stimuli presented in rapid succession. Interference produced by a non-target significantly impaired perception of the target for schizophrenic patients. This effect persisted longer in the schizophrenic subjects possibly because of deficient attentional inhibition.

The Morehouse Faculty Development Program: methods and 3-year outcomes

BACKGROUND AND OBJECTIVES

Faculty development is an established method for increasing the number and effectiveness of faculty in family medicine. However, few published studies focus specifically on the use of faculty development to increase minority representation among faculty. Underrepresented minorities comprise 20% of the nation's population but only 3% of medical school faculty. In the entire nation, only 52 full-time teachers of family medicine are African-Americans. Morehouse School of Medicine has developed an effective model for training large numbers of underrepresented minority physicians to become academic family physicians. From 1993-1996, we trained 23 community-based physicians, three new faculty, six existing faculty, and three full-time fellows as teachers of family medicine. Of 35 participants, 33 were underrepresented minorities. Cultural issues in teaching and communication are an integral part of the curriculum. Seventy-three percent of graduates now teach medical students or residents either full-time or part-time. Further studies are needed to test the replicability of this model in non-minority institutions, as well as to achieve greater cost-effectiveness and improve academic outcomes such as publications and research. Significant faculty diversity is necessary and achievable, if institutions are willing to commit significant resources and network with minority health professionals and institutions.

Distractibility and processing resource deficit in major depression. Evidence for two deficient attentional processing models

Performance on the Stroop Color-Word Test is impaired in depression, but it is not clear whether this impairment reflects a distractor inhibition disturbance or a reduction of processing resources. In this study, untreated major depressives were evaluated using a modified computerized Stroop Test composed of three tasks: to name the color of XXXXXs, of nonconflicting words, and of conflicting color words. It was hypothesized that, unlike color words, nonconflicting word distractors would disturb the color naming task only in the presence of a primary distractor inhibition disturbance. The slow reaction time (RT) depressives and normal RT depressives, according to their color naming speed without distractors, were contrasted to distinguish depressives with and without clear signs of resource deficit. It was found that interference produced by nonconflicting words was greater in normal RT depressives than in either slow RT depressives or control subjects, while interference caused by color words was dramatically stronger in slow RT depressives than in other groups. Results suggest the existence of two different attentional deficit patterns in clinical depression: some depressives have a distractor inhibition disturbance while others are deficient in processing resources.

[Deficit in selective attention and its evolution in depression]

Selective attention was measured in 34 depressed patients and 34 controls using a computerized version of the Stroop test, that included a manipulation of the stimulus onset asynchrony (SCA) in order to explore the efficacy of cognitive inhibition as a function of depression and of clinical amelioration of degression after therapy. Clinical tests included a measure of psychomotor slowing [Echelle de Ralentissement de Widlöcher (ERD), the Hamilton (Psychiatric Rating Scale for Depression (HAMD), and the Brief Psychiatric Rating Scale (BPRS)]. Selective attention was measured with the Stroop test, which includes four measures: Word, Color, Color-Word, and Color-Word minus Color, or interference. All of these measures were deficient in the depressed patients, particularly Stroop interference. Even when additional time was given to inhibit the Stroop distractor in the SOA condition, depressed subjects still showed significantly inferior performance. After four weeks of anti-depressive treatment, fifteen of the patients were retested, and showed significant improvement on all the Stroop measures, particularly on Stroop interference. The improvement in performance on the attentional measures was comparable in magnitude to that seen on the clinical scales, and suggests that the interference measure can be a sensitive indicator of clinical status in depressed patients.

Pleasure as a Sign of Efficacy of Mental Activity

Previous work has shown that sensory pleasure is both the motor and the sign of optimal behaviors aimed at physiological ends. From an evolutionary psychology point of view it may be postulated that mental pleasure evolved from sensory pleasure. Accordingly, the present work tested empirically the hypothesis that pleasure signals efficacious mental activity. In Experiment 1, ten subjects played video-golf on a Macintosh computer. After each hole they were invited to rate their pleasure or displeasure on a magnitude estimation scale. Their ratings of pleasure correlated negatively with the difference par minus performance, i.e., the better the performance the greater the pleasure reported. In Experiments 2 and 3, the pleasure of reading poems was correlated with comprehension, both rated by two groups of subjects, science students and arts students. In the majority of science students pleasure was significantly correlated with comprehension. Only one arts student showed this relationship; this result suggests that the proposed relationship between pleasure and cognitive efficiency is not tautological. Globally, the results support the hypothesis that pleasure is aroused by the same mechanisms, and follows the same laws, in physiological and cognitive mental tasks and also leads to the optimization of performance.

Attention deficits in depression: an electrophysiological marker

EVENT-RELATED POTENTIALS were recorded in young depressed subjects and compared with results from controls. Subjects were required to respond to targets (rare high-frequency sounds) presented to a designated ear, and to ignore targets presented to the non-designated ear as well as standards (frequent low-frequency sounds) presented to either ear. The results confirm those previously obtained with elderly depressed patients, showing the same general profile of electrophysiological and behavioural differences, and in particular a substantial reduction of the N200 amplitude in response to attended targets in depressed subjects. It is suggested that the N200 component could be a marker of depression.

Obesity and hypertension among African Americans: do African-American primary care providers address these conditions when secondary to primary illness?

This study examined the extent that black family medicine residents manage African-American patients with hypertension and obesity secondary to the primary health problem. A retrospective chart survey of 1806 outpatients was used to select a sample of 362 patients being treated by 12 African-American family medicine residents. Of the 362 patient charts, 31.2% of the patients had hypertension (ie, blood pressure > or = 140/90 mm Hg). A plan for managing hypertension was found in the charts for 77% of these patients. Obesity was present among 37% of the patients, and yet there was documentation of a treatment plan for managing this condition for only 38% of these patients. Black family medicine residents appear to be sensitized about addressing the problem of hypertension among African-American patients being treated for other illnesses. However, there is a vital need to teach family medicine physicians how to address and aggressively manage the problem of obesity among African-American patients, particularly those patients for whom obesity was not the primary reason for seeking medical care.

Attention disturbance in clinical depression. Deficient distractor inhibition or processing resource deficit?

Cognitive impairments in depression have recently been proposed as secondary to more basic attentional disturbances. Studies have shown that performance on the Stroop Color-Word Test is impaired in depressives, but it is not clear whether this impairment reflects a primary distractor inhibition disturbance or a more global cognitive dysfunction, such as a reduction of processing resources. In the present study, unmedicated clinical depressives were evaluated using a computerized Stroop Color-Word Test and the Visuo-Spatial Interference Test, a selective attention task that makes fewer demands on resources. Compared with normal subjects, depressives presented increased choice reaction times (CRT) and interference in both tests. Correlations were found between CRT and interferences only in depressives, favoring the processing resource hypothesis. Further exploratory analysis comparing the more rapid depressives and the slower normal subjects on CRT revealed that although these subgroups had comparable CRT, rapid depressives still exhibited increased interference on the Visuo-Spatial Interference Test. Thus, in non- or mildly retarded patients, a specific distractor inhibition deficit was observed in absence of resource deficit.

HLA-DR mismatching correlates with early cardiac allograft rejection, incidence, and graft survival when high-confidence-level serological DR typing is used

To determine if cardiac allograft outcome is improved among patients with fewer HLA-DR mismatches with their donors, we studied 132 recipients of a primary cardiac allograft who were transplanted between December 1985 and December 1991. These recipients and their donors all had high-confidence-level serological HLA-DR typing, previously shown to correlate highly with DNA DR typing. Patients were divided in two groups based on the HLA-DR mismatch with their donors. Group I consisted of 78 patients with 1 or zero DR mismatch and group II of 54 patients with 2 DR mismatches. Allograft outcome measurements included incidence of moderate rejection, incidence of allograft vasculopathy at 12 months, cardiac function measured as left ventricular ejection fraction (LVEF) and cardiac index (CI), and actuarial graft survival up to 7 years. Groups I and group II were not different with regard to recipient age, donor age, ischemia time, pulmonary vascular resistance, sex, or PRA greater than 0%. Group II had a higher incidence of moderate rejection on the first-week biopsy (47% vs. 25%, P = 0.019), and during the first month (84% vs. 58%, P = 0.006), but no difference was found in frequency of rejection from months 2 to 12. LVEF was not different in the groups at any point. CI was better in group I at 12 months (2.76 vs. 2.5, P = 0.03). No statistically significant difference was found in incidence of allograft vasculopathy (17% vs. 26%, P = 0.204). Actual graft survival at 1 year was better for group I (91% vs. 74%, P = 0.008), and actuarial graft survival at 6 years also favored group I (76% vs. 56%, P = 0.04). Using high-confidence-level serological HLA-DR typing assignments we demonstrated that HLA-DR mismatching correlates highly with cardiac allograft outcome. Implications are that heart transplant survival could be improved if prospective matching were feasible and prioritized or if immunosuppression were tailored to the HLA-DR match.

Changing from porcine to human insulin

The development of hypoglycaemia unawareness is associated with long duration of diabetes, improved glycaemic control, alcohol intake and recurrent hypoglycaemia. However, current evidence suggests that neither frequency of severe episodes nor mortality from hypoglycaemia are increased following a change from animal to human insulin. Nevertheless, a small number of patients continue to report an alteration in the nature of hypoglycaemic warning symptoms following a change in insulin species. This is possibly a consequence of a reduced catecholamine response to lowering blood glucose levels or to species differences in the effect of insulin on central nervous system function. In practical terms, it seems sensible to warn patients that the nature of the symptoms associated with hypoglycaemia might alter following conversion from porcine to human insulin. At the time of the changeover, patients should be encouraged to perform frequent blood glucose measurements. Also, the usual insulin dose should be reduced by 10% at the start of human insulin treatment. Other aspects of insulin treatment including injection technique, meal timing, exercise, etc. should be discussed. For patients who are convinced that loss of warning of hypoglycaemia occurred after conversion from porcine to human insulin, a change back to animal insulin would be preferred to relaxing glycaemic control in the first instance. Pressure should be brought to bear on the pharmaceutical industry to maintain the availability of animal insulins for the small number of patients who have experienced problems with human insulin.