Machine learning-enabled exploration of the electrochemical stability of real-scale metallic nanoparticles

Surface Pourbaix diagrams are critical to understanding the stability of nanomaterials in electrochemical environments. Their construction based on density functional theory is, however, prohibitively expensive for real-scale systems, such as several nanometer-size nanoparticles (NPs). Herein, with the aim of accelerating the accurate prediction of adsorption energies, we developed a bond-type embedded crystal graph convolutional neural network (BE-CGCNN) model in which four bonding types were treated differently. Owing to the enhanced accuracy of the bond-type embedding approach, we demonstrate the construction of reliable Pourbaix diagrams for very large-size NPs involving up to 6525 atoms (approximately 4.8 nm in diameter), which enables the exploration of electrochemical stability over various NP sizes and shapes. BE-CGCNN-based Pourbaix diagrams well reproduce the experimental observations with increasing NP size. This work suggests a method for accelerated Pourbaix diagram construction for real-scale and arbitrarily shaped NPs, which would significantly open up an avenue for electrochemical stability studies.

Interpretable Deep Learning Model for Analyzing the Relationship between the Electronic Structure and Chemisorption Property

The use of machine learning (ML) is exploding in materials science as a result of its high predictive performance of material properties. Tremendous trainable parameters are required to build an outperforming predictive model, which makes it impossible to retrace how the model predicts well. However, it is necessary to develop a ML model that can extract human-understandable knowledge while maintaining performance for a universal application to materials science. In this study, we developed a deep learning model that can interpret the correlation between surface electronic density of states (DOSs) of materials and their chemisorption property using the attention mechanism that provides which part of DOS is important to predict adsorption energies. The developed model constructs the well-known d-band center theory without any prior knowledge. This work shows that human-interpretable knowledge can be extracted from complex ML models.

Accelerated mapping of electronic density of states patterns of metallic nanoparticles via machine-learning

Within first-principles density functional theory (DFT) frameworks, it is challenging to predict the electronic structures of nanoparticles (NPs) accurately but fast. Herein, a machine-learning architecture is proposed to rapidly but reasonably predict electronic density of states (DOS) patterns of metallic NPs via a combination of principal component analysis (PCA) and the crystal graph convolutional neural network (CGCNN). With the PCA, a mathematically high-dimensional DOS image can be converted to a low-dimensional vector. The CGCNN plays a key role in reflecting the effects of local atomic structures on the DOS patterns of NPs with only a few of material features that are easily extracted from a periodic table. The PCA-CGCNN model is applicable for all pure and bimetallic NPs, in which a handful DOS training sets that are easily obtained with the typical DFT method are considered. The PCA-CGCNN model predicts the R2 value to be 0.85 or higher for Au pure NPs and 0.77 or higher for Au@Pt core@shell bimetallic NPs, respectively, in which the values are for the test sets. Although the PCA-CGCNN method showed a small loss of accuracy when compared with DFT calculations, the prediction time takes just ~ 160 s irrespective of the NP size in contrast to DFT method, for example, 13,000 times faster than the DFT method for Pt147. Our approach not only can be immediately applied to predict electronic structures of actual nanometer scaled NPs to be experimentally synthesized, but also be used to explore correlations between atomic structures and other spectrum image data of the materials (e.g., X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy).

Reducing Time to Discovery: Materials and Molecular Modeling, Imaging, Informatics, and Integration

Multiscale and multimodal imaging of material structures and properties provides solid ground on which materials theory and design can flourish. Recently, KAIST announced 10 flagship research fields, which include KAIST Materials Revolution: Materials and Molecular Modeling, Imaging, Informatics and Integration (M3I3). The M3I3 initiative aims to reduce the time for the discovery, design and development of materials based on elucidating multiscale processing-structure-property relationship and materials hierarchy, which are to be quantified and understood through a combination of machine learning and scientific insights. In this review, we begin by introducing recent progress on related initiatives around the globe, such as the Materials Genome Initiative (U.S.), Materials Informatics (U.S.), the Materials Project (U.S.), the Open Quantum Materials Database (U.S.), Materials Research by Information Integration Initiative (Japan), Novel Materials Discovery (E.U.), the NOMAD repository (E.U.), Materials Scientific Data Sharing Network (China), Vom Materials Zur Innovation (Germany), and Creative Materials Discovery (Korea), and discuss the role of multiscale materials and molecular imaging combined with machine learning in realizing the vision of M3I3. Specifically, microscopies using photons, electrons, and physical probes will be revisited with a focus on the multiscale structural hierarchy, as well as structure-property relationships. Additionally, data mining from the literature combined with machine learning will be shown to be more efficient in finding the future direction of materials structures with improved properties than the classical approach. Examples of materials for applications in energy and information will be reviewed and discussed. A case study on the development of a Ni-Co-Mn cathode materials illustrates M3I3's approach to creating libraries of multiscale structure-property-processing relationships. We end with a future outlook toward recent developments in the field of M3I3.

Synthesis of Chemically Ordered Pt3Fe/C Intermetallic Electrocatalysts for Oxygen Reduction Reaction with Enhanced Activity and Durability via a Removable Carbon Coating

Recently, Pt₃M (M = Fe, Ni, Co, Cu, etc.) intermetallic compounds have been highlighted as promising candidates for oxygen reduction reaction (ORR) catalysts. In general, to form those intermetallic compounds, alloy phase nanoparticles are synthesized and then heat-treated at a high temperature. However, nanoparticles easily agglomerate during the heat treatment, resulting in a decrease in electrochemical surface area (ECSA). In this study, we synthesized Pt-Fe alloy nanoparticles and employed carbon coating to protect the nanoparticles from agglomeration during heat treatment. As a result, Pt₃Fe L1₂ structure was obtained without agglomeration of the nanoparticles; the ECSA of Pt-Fe alloy and intermetallic Pt₃Fe/C was 37.6 and 33.3 m² g_Pt^-1, respectively. Pt₃Fe/C exhibited excellent mass activity (0.454 A mg_Pt^-1) and stability with superior resistances to nanoparticle agglomeration and iron leaching. Density functional theory (DFT) calculation revealed that, owing to the higher dissolution potential of Fe atoms on the Pt₃Fe surface than those on the Pt-Fe alloy, Pt₃Fe/C had better stability than Pt-Fe/C. A single cell fabricated with Pt₃Fe/C showed higher initial performance and superior durability, compared to that with commercial Pt/C. We suggest that Pt₃M chemically ordered electrocatalysts are excellent candidates that may become the most active and durable ORR catalysts available.

CO oxidation by MoS2-supported Au19 nanoparticles: effects of vacancy formation and tensile strain

The mechanism of the catalytic oxidation of CO activated by MoS₂-supported Au₁₉ nanoparticles (NPs) was studied using density functional theory calculations.

Indomethacin decreases optic nerve oxygen tension by a mechanism other than cyclo-oxygenase inhibition

AIMS

We investigated the effect of several Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), on the preoptic nerve oxygen tension (ONPO2), as indomethacin previously has demonstrated a strong decreasing effect on ONPO2. We tested whether these NSAIDs, like indomethacin, also reduce the increasing effect of dorzolamide on ONPO2.

METHODS

ONPO2 was measured 0.5 mm above the optic disc in 23 domestic pigs (26-36 kg) with a polarographic oxygen-sensitive electrode. One of the following NSAIDs was administered intravenously as increasing doses or as one large dose: indomethacin, ibuprofen, diclofenac, ketoprofen, parecyclo-oxygenase-2 inhibitor and lornoxicam. Indomethacin was both tested alone and after preceding administration of the other NSAIDs. Dorzolamide was also tested after preceding administration of NSAIDs different from indomethacin.

RESULTS

Indomethacin decreased ONPO2 significantly in a dose-dependent manner. None of the other NSAIDs produced any effect on the ONPO2 (p>>0.05; n = 17). No difference was found between the effect of indomethacin injected alone, and after preceding administration of the other NSAIDs. Intravenous dorzolamide (500 mg) increased ONPO2 by 32 (7)% (n = 7; p<0.001) after preceding administration of several NSAIDs different from indomethacin.

CONCLUSIONS

Indomethacin decreased ONPO2, while the other NSAIDs showed no effect on ONPO2, and they did not affect the effect of indomethacin. The hypoxic effect of indomethacin must be due to another mechanism than cyclo-oxygenase inhibition. The effect of dorzolamide on ONPO2 is not related to prostaglandin production.

Alemtuzumab (ALZ) as treatment for severe paraneoplastic pemphigus (PNP) associated to B-cell chronic lymphocytic leukemia (CLL)

16520

Background: ALZ is a monoclonal antibody used in the treatment of CLL. PNP is a mucocutaneous disease frequently associated with B-cell malignancies. PNP is often refractory to immunosuppressive drugs and is frequently fatal. Methods: We here report two cases, where ALZ induced a complete and sustained remission of both PNP and CLL and one case with a significant remission of PNP alone. Results: A 68-year old male with a 4-year CLL history developed blisters and ulcers on the extremities and trunk and severe stomatitis. Despite steroids, fludarabine, cyclophosphamide, ciclosporin A, and azathioprin, PNP exacerbated. A standard 12-weeks ALZ schedule was initiated. PNP lesions gradually regressed under the last weeks of treatment and resolved completely a few weeks later. A bone marrow biopsy showed morphologic and flowcytometric signs of remission. Now, 30 months after ALZ, the patient’s PNP and CLL are still in remission. Almost a year after this first case, a 77-year old male with a 3-year CLL history, presented with severe mucocutaneous lesions of the lips, oro-esophageal cavity, penis and extremities. PNP was diagnosed and a standard 12-weeks ALZ schedule was initiated. The lesions began to regress during the last weeks of treatment and normalized within the subsequent 8 weeks. This remission had a duration of 1½ year, after which the patient was hospitalized with evidence of PNP relapse. He is currently undergoing renewed ALZ therapy. An 80-year old female with a 4-year history of CLL, showed signs of disease progression after 2 treatment-free years.She then developed mucocutaneous lesions diagnosed as PNP. In spite of cytoreductive treatment, both PNP and CLL progressed and ALZ was given. All PNP lesions promptly disappeared, but recurred already 2 weeks after discontinuation of ALZ. Concomitantly, the patient developed a Legionella pneumonia. In spite of erythromycin, she deteriorated clinically and died one month later. At autopsy, marked CLL involvement of bone marrow and retroperitoneal lymph nodes was found. Conclusion: ALZ is an effective treatment in severe CLL-associated PNP. The observed duration of response was variable. A larger number of patient observations is necessary in order to identify patterns of response.

No significant financial relationships to disclose.

Clinical efficacy and plasma concentrations of two formulations of buparvaquone in cattle infected with East Coast fever (Theileria parva infection)

East Coast fever, caused by the protozoan parasite Theileria parva, kills about 600,000 cattle annually in Africa. The hydroxynaphthoquinone compound buparvaquone (BPQ) is curative. Sixteen calves were infected with T. parva. On manifestation of disease symptoms, eight were injected with the original (pioneer) BPQ product and eight with a test product containing BPQ. All 16 calves were cured by one injection of 2.5 mg BPQ/kg bodyweight. The concentration of BPQ in blood plasma was monitored by HPLC. The mean observed C(max) of BPQ was 0.229 and 0.253 microg/mL of plasma, the mean observed time to reach this concentration (T(max)) was 2.62 and 2.12 h and the AUC (area under curve) was 4.785 and 4.156 microg h/mL, respectively, for the pioneer and test product. Considerable variations occurred in the plasma concentration of BPQ within each group. They showed no relationship with either clinical or parasitological parameters following treatment.

Indomethacin lowers optic nerve oxygen tension and reduces the effect of carbonic anhydrase inhibition and carbon dioxide breathing

BACKGROUND/AIMS

Prostaglandins are important in blood flow regulation. Carbon dioxide (CO(2)) breathing and carbonic anhydrase inhibition increase the oxygen tension in the retina and optic nerve. To study the mechanism of this effect and the role of cyclo-oxygenase in the regulation of optic nerve oxygen tension (ONPO(2)), the authors investigated how indomethacin affects ONPO(2) and the ONPO(2) increases caused by CO(2) breathing and carbonic anhydrase inhibition in the pig.

METHODS

Optic nerve oxygen tension was measured in 11 pigs with a polarographic oxygen electrode. The tip of the electrode was placed 0.5 mm above the optic disc. The effects of indomethacin, CO(2) breathing (3%) before and after indomethacin treatment, and carbonic anhydrase inhibition with or without indomethacin treatment were investigated.

RESULTS

Administration of 300 mg indomethacin decreased optic nerve oxygen tension significantly. Carbonic anhydrase inhibition and CO(2) breathing increased ONPO(2) significantly. After indomethacin had been given, the rise in ONPO(2) caused by CO(2) breathing and carbonic anhydrase inhibition was significantly reduced.

CONCLUSION

Systemic administration of indomethacin decreases the optic nerve oxygen tension; this is probably the result of decreased blood flow through vasoconstriction of vessels in the optic nerve. Additionally, indomethacin diminishes the ONPO(2) increasing effect of CO(2) breathing and carbonic anhydrase inhibition, thus affecting the reactivity of vessels in the optic nerve.

Optic nerve oxygen tension: the effects of timolol and dorzolamide

BACKGROUND/AIMS

The authors have previously reported that carbonic anhydrase inhibitors such as acetazolamide and dorzolamide raise optic nerve oxygen tension (ONPO(2)) in pigs. The purpose of the present study was to investigate whether timolol, which belongs to another group of glaucoma drugs called beta blockers, has a similar effect. In addition, the effect of dorzolamide and timolol in combination was studied.

METHODS

Polarographic oxygen electrodes were placed transvitreally over the optic disc in anaesthetised pigs and ONPO(2) was recorded continually. Drugs were administered intravenously either as 100 mg timolol followed by 500 mg dorzolamide (n = 5), 500 mg dorzolamide followed by 100 mg timolol (n = 5), or 100 mg timolol and 500 mg dorzolamide given simultaneously (n = 5). Arterial blood pressure, blood gasses, and heart rate were recorded.

RESULTS

ONPO(2) was unaffected by administration of 100 mg timolol as an intravenous injection (n = 5). Administration of 500 mg dorzolamide by itself significantly increased ONPO(2) from 2.96 (SD 0.62) kPa to 3.69 (SD 0.88) kPa (n = 4, p = 0.035). The dorzolamide induced ONPO(2) increase was not significantly different from the ONPO(2) increases were seen when dorzolamide was administered simultaneous with (n = 5) or 35 minutes (n = 5) after 100 mg timolol.

CONCLUSION

Systemic administration of timolol does not affect the optic nerve oxygen tension despite its lowering effect on the intraocular pressure. Additionally, timolol does not affect the ONPO(2) increasing effect of dorzolamide.

The vortex concentrator for suspended solids treatment

The use of vortex concentrators is becoming increasingly popular for suspended solids reduction in combined sewer overflows and stormwater. This study is a laboratory investigation of the use of vortex concentrators to reduce the solids concentration of synthesized stormwater. The synthesized stormwater was made with water and addition of particles; sand, granular activated carbon, and sewer sediments. The vortex concentrator was made of acryl resin 300 mm in diameter. To determine the efficiency for various influent suspended solids (SS) concentrations, tests were performed with different SS concentrations. The samples were taken simultaneously at the influent storage tank and effluent tank, and measured SS concentrations. The range of surface loading rates were 120 to 850 m3/m2/day, and influent SS concentrations were varied from 300 to 5,000 mg/L. To determine the optimum coagulant dosage, jar tests were conducted with coagulants such as PAM and PAC. It was found that optimum coagulant and its dosage were PAM and 2 mg/L. The overall SS removal efficiency of the vortex concentrator for typical stormwater was estimated at about 65%. With an increase of SS concentration, the removal efficiency was increased. Since the SS concentration of stormwater was higher than 1,000 mg/L, the removal efficiency of the vortex concentrator for stormwater could be estimated to be 65-70%. The SS removal efficiency was increased with an increase of retention time, and the optimum retention time was 0.15-1.0 minutes. With an increase of the foul to overflow Q(F)/Q(o), a key parameter for vortex concentrator operation, the removal efficiency was increased. An alternative solution to improve treatment efficiency might be to set a follow-up retention basin. Based on a series of settling tests on the treated overflow water from the vortex concentrator, 5 to 10 minutes hydraulic retention time in a follow-up retention basin would substantially improve the results.

Development and validation of a questionnaire for diagnosing atopic dermatitis

In this paper we describe the development and validation of a questionnaire for atopic dermatitis used in population surveys in Denmark. The Danish questionnaire was developed from the UK Working Party's questionnaire for atopic dermatitis and includes a severity score. The study included 61 children aged 3 to 14 years recruited from our Department of Dermatology, two kindergartens and a primary school. A validator was appointed to evaluate whether each child had current or previous atopic dermatitis. Compared to the validator's diagnosis, the sensitivity of the UK Working Party criteria was 90% (95% CI; 74-98) and the specificity was 97% (95% CI; 82-99). The criteria for atopic dermatitis have a satisfactory sensitivity and specificity for diagnosing current atopic dermatitis, but the natural course of the disease complicates the validation of investigational instruments. We suggest that future epidemiological studies aimed at establishing new knowledge on atopic dermatitis should include history, current symptoms and findings and a severity score.

Organochlorine burdens in blood of ringed and bearded seals from north-western Svalbard

Ringed seal (Phoca hispida) and bearded seal (Erignathus barbatus) are the main prey of polar bears (Ursus maritimus), and information on organochlorines (OCs) in these pinniped species is important to understand the transport, fate and effects of persistent organic pollutants in the Arctic ecosystem. Thus, OCs were analysed in blood samples of bearded and ringed seals from the coastal ecosystem of the north-western Svalbard archipelago (Kongsfjorden, 78.55degrees N). The relative contribution of OCs could be ranked as follows: Ringed seal females: sigmaPCB > sigma DDT > sigma CHL > sigma HCH > HCB > Mirex. Ringed seal males: sigma PCB > or = sigma DDT > sigma CHL > sigma HCH > or = HCB > Mirex. Bearded seal females: sigma PCB > sigma HCH > or = sigma CHL > sigma DDT > Mirex > HCB. Bearded seal males: sigma PCB > sigma DDT > or = sigma CHL > sigma HCH > Mirex > or = HCB. The concentrations of sigmaPCB and sigma DDT were higher in ringed seals than in bearded seals, whereas sigma HCH was higher in bearded than in ringed seals. In ringed seal females and males sigma PCB was 337 +/- 95 ng/g (n= 6) and 625 +/- 443 ng/g (n=6), whereas sigma DDT was 165 +/- 47 ng/g (n=6) and 621 +/- 559 ng/g (n = 6), respectively. In bearded seal females and males, sigmaPCB was 159 +/- 132 ng/g (n = 6) and 248 +/- 93 ng/g (n = 5), whereas sigmaDDT was 46 +/- 41 ng/g (n = 6) and 161 +/- 71 ng/g (n = 5), respectively. The inter-species differences are caused by a higher trophic position of ringed seals in the Svalbard ecosystem compared to bearded seals. OC levels in ringed seals at Svalbard are similar to those reported from the North-American Arctic and in the lower range compared to previously reported data from Svalbard.

CD4+ CD8+ (thymocyte-like) T lymphocytes present in blood and skin from patients with atopic dermatitis suggest immune dysregulation

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease expressed early in life. Disease development is primarily determined by as yet unknown genetic factors, leading to the accumulation of activated T lymphocytes in the skin.

OBJECTIVES

To investigate the nature of these T cells.

METHODS

T-cell lines could be established from AD skin biopsies, but not from normal skin or AD peripheral blood, when placed in RPMI 1640 medium with 10% human AB serum, antibiotics, and the T-lymphocyte growth factors interleukins 2 and 4. The cell lines were subjected to phenotypic analysis using a fluorescence-activated cell sorter and compared with lymphocytes from AD and normal control peripheral blood.

RESULTS

T-cell lines from 22 of 24 consecutive skin biopsies taken from 24 adult patients with AD were established. All cells were T lymphocytes expressing several activation markers. A significant proportion of the lymphocytes had stable expression of a CD4+ CD8+ phenotype (26% +/- 6%; mean +/- SEM). Such double-positive T lymphocytes are normally only seen in the thymus and not in the peripheral immune system. CD4+ CD8+ cells in peripheral blood of the patients (12.5% +/- 3.3%) were also detected.

CONCLUSIONS

We suggest that a basic pathophysiological change in AD may be a faulty maturation of the T-lymphocyte system, leading to skin inflammation with CD4+ CD8+ T lymphocytes resembling immature T cells. This is likely to lead to skewing of many immune reactions in the patients.

Reliability of Information Collected by Proxy in Family Studies of Alzheimer’s Disease

The study evaluated the reliability of data obtained from proxy informants. The index subjects in this study were 81 nondemented participants in the Multi-Institutional Research in Alzheimer Genetic Epidemiology (MIRAGE) study. These index subjects and 159 proxy informants, identified by the index subjects, participated in the study. The kappa statistic with multiple raters per subject (for dichotomous variables) and the intraclass correlation coefficient (for continuous variables) were used to measure reliability. Among proxy respondents who provided answers, there was excellent agreement between proxy responses and the responses of the index subjects (0.7 < or = kappa < or =0.9), with the exception of questions about head injury (kappa = 0.4). A large proportion (>90%) of the proxy informants in this study were able to provide information on most items. Higher nonresponse rates (as high as 30%) were observed for medication history and women's health questions. This study supports the reliability of proxy responses for most categories of questions that are elicited in typical epidemiological studies, including the MIRAGE study.

Cytokine expression of skin T-lymphocytes from patients with atopic dermatitis

We analysed the cytokine profile of skin T cells by establishing 11 T-cell lines from adult patients with moderate-to-severe atopic eczema using T-cell growth factors interleukin-2 and interleukin-4. We compared T-cell lines from lesional skin of atopic dermatitis patients with those from non-atopic skin of patients with other skin diseases, observing that T-cell lines of patients with atopic dermatitis unstimulated cultures expressed a Th1 profile. After stimulation with anti-CD3 and anti-CD28 monoclonal antibodies, the cytokine expression showed rapid initial upregulation of Th2 followed by a Th1 profile. Furthermore, strong upregulation of interleukin-10 was observed after 24 h stimulation. Our findings suggest that skin T-lymphocytes from atopic dermatitis patients seem to consist of a heterogenous population of Th1 and Th2 or Th0 cells and the results for secreted cytokines indicate that T-cell lines from each inflammatory skin disease showed the corresponding disease-specific original cytokine profile.

Proliferation of T lymphocytes from atopic dermatitis skin is enhanced upon anti-CD3, reduced upon mitogen and superantigen, and negligible upon tuberculin stimulation

Knowledge about the nature of lymphocytes infiltrating atopic dermatitis skin is restricted to allergen-specific T cells. We investigated the proliferative capacities of T lymphocytes cultured in an antigen-independent way from biopsies of atopic dermatitis skin. When compared with peripheral blood mononuclear cells (PBMC) from healthy donors or atopic dermatitis patients, the skin-homing lymphocytes proliferated more vigorously in response to stimulation with anti-CD3 antibodies (1 microglml), reflecting their high response capacity. When stimulated with phytohemagglutinin (10 microg/ml) or staphylococcal enterotoxin A (0.1 microg/ml) the skin-homing lymphocytes achieved significantly lower proliferation levels than PBMC. In contrast to normal and atopic PBMC the skin-homing lymphocytes did not respond to tuberculin purified protein derivative (10 microg/ml). In the mixed lymphocyte reaction the skin-homing lymphocytes did not stimulate autologous PBMC to proliferate. We conclude that skin-homing lymphocytes have more pronounced immune deviations than PBMC in patients with atopic dermatitis. They represent a valuable approach for further investigating the pathogenesis of the disease.

Telomerase activity is increased and telomere length shortened in T cells from blood of patients with atopic dermatitis and psoriasis

We studied telomerase activity and telomere length in PBMC and purified CD4(+) and CD8(+) T cells from blood obtained from a total of 32 patients with atopic dermatitis, 16 patients with psoriasis, and 30 normal controls. The telomerase activity was significantly increased in PBMC from the patients compared with PBMC from normal donors. This increase was most pronounced in the subpopulation of CD4(+) T cells, which were significantly above the activity of the CD8(+) T cells in atopic dermatitis, psoriasis patients, and control persons. The telomere length was significantly reduced in all T cell subsets from both atopic dermatitis and psoriasis patients compared with normal individuals. Furthermore, the telomere length was found to be significantly shorter in CD4(+) memory T cells compared with the CD4(+) naive T cells, and both of the cell subsets from diseases were shown to be of significantly shorter telomere length than the same cell subsets from normal controls. No significant difference was observed between CD8(+)CD28(-) and CD8(+)CD28(+) T cell populations in both diseases. However, the telomere length of CD8(+)CD28(+) T cells from both diseases was significantly shorter than CD8(+)CD28(+) T cell subsets from normal donors. In conclusion, the increased telomerase activity and shortened telomere length indicates that T lymphocytes in atopic dermatitis and psoriasis are chronically stimulated and have an increased cellular turnover in vivo.

A Th2 chemokine, TARC, produced by keratinocytes may recruit CLA+CCR4+ lymphocytes into lesional atopic dermatitis skin

Atopic dermatitis is an inflammatory skin disease in which the inflammation is characterized by the influx of lymphocytes into the dermis. It is generally believed that atopic dermatitis is a Th2-type disease, i.e., the T lymphocytes produce interleukin-4, interleukin-5, interleukin-10, and interleukin-13, although it has become evident in recent years that the cytokine profile in the skin changes during the course of the disease towards a Th1-Th2 mixed cytokine profile (interferon-gamma, tumor necrosis factor alpha, and interleukin-2). The lymphocytes that home into the skin express cutaneous lymphocyte-associated antigen, and it has recently been shown that most of the lymphocytes in this population express the chemokine receptor CCR4. CCR4 is the receptor for the CC chemokine TARC (thymus and activation regulated chemokine), and this chemokine is expressed predominantly by keratinocytes in the basal layer of the epidermis of lesional atopic dermatitis skin in mice. In humans, however, it was shown to be expressed in the endothelial cells of the dermis. We have examined the peripheral blood mononuclear cells of atopic dermatitis patients for the expression of cutaneous lymphocyte-associated antigen and CCR4 and compared them with peripheral blood mononuclear cells from normal controls. We found that the proportion of CLA+CCR4+ lymphocytes is upregulated in atopic dermatitis patients. In addition we have examined skin biopsies of lesional and non-lesional skin from atopic dermatitis patients and found that the keratinocytes, but not the endothelial cells, produce TARC in the lesional but not in the nonlesional skin. To gain insight in the stimulatory mechanisms for TARC production in keratinocytes, as previously observed in mice, we cultured HaCaT cells and found that interferon-gamma and tumor necrosis factor alpha work synergistically to induce TARC production. These observations suggest that the induction of TARC production in keratinocytes plays an important role in the late phase skin invasion by CCR4+CLA+ Th2-type lymphocytes in atopic dermatitis.

Optic nerve oxygen tension: effects of intraocular pressure and dorzolamide

AIM

To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide.

METHODS

Domestic pigs were used as experimental animals. Oxygen tension was measured by means of a polarographic electrode in the vitreous 0.5 mm anterior to the optic disc. This entity is called the optic nerve oxygen tension. Intraocular pressure was controlled by a hypodermic needle inserted into the anterior chamber and connected to a saline reservoir.

RESULTS

When the intraocular pressure was clamped at 20 cm H2O optic nerve oxygen tension was 20 (5) mm Hg (n=8). Intravenous administration of dorzolamide caused an increase in optic nerve oxygen tension of 43 (8)% (n=6). Both before and after administration of dorzolamide optic nerve oxygen tension was unaffected by changes in intraocular pressure, as long as this pressure remained below 60 cm H2O. At intraocular pressures of 60 cm H(2)O and below, dorzolamide significantly increased optic nerve oxygen tension.

CONCLUSION

Intravenous administration of 500 mg dorzolamide increases the oxygen tension at the optic nerve head during acute increases in intraocular pressure.

Telomerase activity is spontaneously increased in lymphocytes from patients with atopic dermatitis and correlates with cellular proliferation

Telomerase is a ribonucleoprotein enzyme involved with cellular proliferation and cellular senescence. The aim of the present study was to investigate telomerase activity in lymphocytes from patients with atopic dermatitis (AD) and to observe its regulation of cellular proliferation. Peripheral blood mononuclear cells (PBMC) were isolated from 15 patients with AD and 13 healthy donors. Cells were stimulated with purified protein derivative (PPD) of tuberculin (10 microg/ml), interleukin 2 (IL-2) (100 U/ml), anti-CD3 monoclonal antibody (anti-CD3) (1 microg/ml), anti-CD3 plus IL-2, and staphylococcal enterotoxin A (SEA) (0.1 microg/ml). Telomerase activity was measured by the telomeric repeat amplification protocol-based telomerase polymerase chain reaction enzyme-linked immunosorbent assay at 0 and 72 h of incubation. In addition, DNA synthesis of the cells was assayed using 3H-thymidine incorporation. We found that telomerase activity in non-stimulated PBMC from patients with AD was significantly up-regulated without any stimulation during the 72 h of in vitro incubation. The most potent stimulator of telomerase activity was SEA, followed by anti-CD3 plus IL-2, anti-CD3 alone, and PPD. IL-2 did stimulate telomerase activity and DNA proliferation with increasing dosage of IL-2. The DNA proliferation was paralleled by increase in telomerase activity. There was no significant difference between telomerase activity in stimulated lymphocytes from AD patients and normal donors, but the relative increase in telomerase activity tended to be less in AD patients. A spontaneously higher telomerase activity in lymphocytes from AD patients could indicate that T lymphocytes are already stimulated in vivo or that a population of T cells in peripheral blood exhibits an increased telomerase activity compatible with cellular immaturity.

Optic nerve oxygen tension in pigs and the effect of carbonic anhydrase inhibitors

PURPOSE

To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture.

METHODS

Polarographic oxygen electrodes were placed in the vitreous humor immediately over the optic disc in 20 anesthetized pigs. Blood gasses and cardiovascular physiology were monitored. ONP(O)2 was recorded continuously with breathing gasses of 21% O2-79% N2, 100% O2, 20% O2-80% N2, and 5.19% CO2-19.9%, O2-74.9% N2. Acetazolamide (15-1000 mg) and dorzolamide (6-1000 mg) were administered intravenously.

RESULTS

The mean (+/- SD) ONP(O)2 was found to be 24.1+/-11.6 mm Hg when the pigs were breathing room air and 50.7+/-29.3 mm Hg when they were breathing 100% O2 (n = 15; P < 0.001). In response to breathing 5.19% CO2, ONP(O)2 changed from 20.8+/-5.6 mm Hg (with 20.0% O2) to 28.9+/-3.6 mm Hg (n = 4; P < 0.001). Intravenous injections of 500 mg dorzolamide increased ONP(O)2 from 16.4+/-6.1 mm Hg to 26.9+/-12.2 mm Hg, or 52.5%+/-21.2% (n = 5; P = 0.017). A dose-dependent effect on ONP(O)2 was seen with intravenous dorzolamide doses of 1000, 500, 250, 125, 63, 27, 15, and 6 mg. Intravenous injections of 500 mg acetazolamide increased ONP(O)2 from 23.6+/-9.5 mm Hg to 30.9+/-10.0 mm Hg (n = 6; P < 0.001), and a dose-dependent effect was seen with doses of 1000, 500, 250, 125, 31, and 15 mg.

CONCLUSIONS

ONP(O)2 is significantly increased by the carbonic anhydrase inhibition of dorzolamide and acetazolamide, and the effect is dose dependent. These data demonstrate for the first time a direct effect of carbonic anhydrase inhibitors on ONP(O)2.

Telomerase activity and telomere length in lymphocytes from patients with cutaneous T-cell lymphoma

BACKGROUND

Telomeres shorten with successive cell divisions in normal somatic cells. Telomerase is a ribonucleoprotein enzyme associated with cellular proliferation and plays an important role in maintaining the stability of chromosomes and the length of DNA telomeres. Telomerase activity has been detected in tissues from many human tumors, but is not present in the majority of normal tissues. Thus, measurement of telomerase activity and telomere length may contribute to understanding the mechanism of tumorigenesis and provide useful diagnostic or prognostic information. The aim of this study was to investigate the telomerase activity and telomere length from patients with cutaneous T-cell lymphoma (CTCL).

METHODS

Eighteen skin-homing T-cell lines were established from skin biopsies and 10 peripheral blood mononuclear cells (PBMC) were isolated from patients with various stages of CTCL together with 22 PBMC from healthy donors. For each sample an identical amount of cellular protein was measured quantitatively for telomerase activity using the telomerase polymerase chain reaction-enzyme-linked immunosorbent assay based on the telomeric repeat amplification protocol method. Telomere length was assayed using a commercial kit.

RESULTS

Eight of ten PBMC and 16 of 18 skin-homing T-cell lines from patients with CTCL showed moderate to strong telomerase activity. Freshly obtained PBMC from healthy donors showed weak levels of telomerase activity. A shorter telomere length was found in cell lines and PBMC from patients with CTCL compared with healthy controls. Four skin-homing T-cell lines going into growth crisis showed sharply reduced telomerase activity.

CONCLUSIONS

The results of the current study indicate that both skin-homing T-cells and PBMC from CTCL have high telomerase activity and short telomere length. These changes are similar to the changes observed in the majority of malignant cells including other types of T-cell lymphoma. It is interesting to note that even in the very early stages of CTCL such as parapsoriasis (which is a clinically benign disease) the changes already are present, indicating that a significantly high level of telomerase activity frequently occurs in CTCL and may be an important event in tumorigenesis. Telomerase activity and telomere length are useful markers for CTCL risk assessment.

Gentacoll hampers epithelialisation and neovascularisation in excisional wounds in hairless mice

Our aim was to analyse the effect of Gentacoll on the rate of epithelialisation and neovascularisation in wound healing. Standardised circular full thickness dermal wounds 2.25 mm in diameter were created on the dorsum of each ear on 24 hairless homozygous mice (n = 48). The cartilaginous layer was left intact. The wounds were treated in a randomised blinded fashion with bovine collagen implants with gentamicin (Gentacoll) (n = 17); bovine collagen implants without gentamicin (n = 15); and Silicone film (n = 16). Epithelialisation and neovascularisation were measured directly by intravital video-microscopy and computerised planimetry immediately after the wounds had been made and every third day until the wounds closed. Only five of the wounds treated with Gentacoll (n = 17) epithelialised completely; and their mean (SEM) epithelialisation time was 22.8 (1.6) days, significantly longer than controls without gentamicin (n = 15) for which the corresponding figures were 14.5 (0.6) days. In nine wounds treated with Gentacoll the ear cartilage in the wound bed perforated and two wounds developed severe inflammation, which was followed by self-mutilation. Neovascularisation was incomplete in all of the wounds in the Gentacoll group, whereas it was completed by 25.3 (0.7) days in the control group treated with implants without gentamicin. In the silicone treated group (n = 16), epithelialisation was completed by 12.7 (0.7) days and neovascularisation by 25.1 (0.5) days. None of wounds treated with collagen or silicone alone showed reactions similar to the Gentacoll-treated ears. Gentacoll hampers epithelialisation and neovascularisation, and might damage exposed cartilage.

Urinary calcium excretion and renal calbindin-D28k

The present investigation examined the possible influence of urinary calcium excretion on the concentration of renal calbindin-D28k. Thiazide diuretics stimulate calcium transport across the epithelial cells of the distal tubule, which express calbindin-D28k in high concentrations. Calbindin-D28k is assumed to facilitate transcellular Ca diffusion. Reduced urine calcium excretion and increased urine output were induced in Wistar rats by infusion of bendroflume-thiazide 1 mg/kg/day. The two control groups had infusions of either furosemide 20 mg/kg/day or vehicle, n = 8 in each group. Urinary Ca excretion was reduced to 10% in the thiazide group and increased by 50% in the furosemide group. Renal concentrations of calbindin-D28 showed no difference between vehicle, thiazide- and furosemide-treated rats. No differences in plasma concentrations of calcium, magnesium, phosphorus, urea, PTH, calcitonin and 1,25-(OH)2D were found between the groups. The present study describes that urine calcium excretion selectively can be manipulated without accompanying changes in renal calbindin-D28k concentrations. The data, therefore, suggest that urinary calcium excretion is not a significant determinator of cytosolic concentrations of renal calbindin-D28k.

Treatment of pleural empyema secondary to pneumonia: thoracocentesis regimen versus tube drainage

BACKGROUND

Pleural empyema is a well known complication of pneumonia. Attitudes differ, however, about the best treatment of this condition and the place of drainage, early operation, and local antibiotics.

METHODS

In a retrospective study 94 consecutive patients with verified empyema caused by pneumonia were admitted to the department of either pulmonary medicine or thoracic surgery. Treatment was either by a lavage regimen (daily thoracocentesis, saline rinse, systemic antibiotics, and in some patients instillation of local antibiotics) in the medical ward (51 patients) or by tube drainage and systemic antibiotics in the surgical unit (43 patients).

RESULTS

The stay in hospital was significantly shorter in the medically treated patients than in the surgical group--2.3 v 5.0 weeks respectively. Furthermore, pleurocutaneous and bronchopleural fistulas developed more frequently in patients treated by tube drainage than in those treated with the thoracocentesis regimen alone (13 (30%) v 5 (10%) and 6 (14%) v 2 (4%) for each complication respectively). The overall mortality was 8.5% with no differences between treatments.

CONCLUSIONS

Treatment with a lavage regimen plus local and systemic antibiotics seems to be associated with a lower frequency of complications and a shorter duration of hospital stay than tube drainage and systemic antibiotics. These results should be confirmed by a prospective, randomised study.