EPR-ENDOR characterization of (17O, 1H, 2H) water in manganese catalase and its relevance to the oxygen-evolving complex of photosystem II

The synthesis of efficient water-oxidation catalysts demands insight into the only known, naturally occurring water-oxidation catalyst, the oxygen-evolving complex (OEC) of photosystem II (PSII). Understanding the water oxidation mechanism requires knowledge of where and when substrate water binds to the OEC. Mn catalase in its Mn(III)-Mn(IV) state is a protein model of the OEC's S(2) state. From (17)O-labeled water exchanged into the di-μ-oxo di-Mn(III,IV) coordination sphere of Mn catalase, CW Q-band ENDOR spectroscopy revealed two distinctly different (17)O signals incorporated in distinctly different time regimes. First, a signal appearing after 2 h of (17)O exchange was detected with a 13.0 MHz hyperfine coupling. From similarity in the time scale of isotope incorporation and in the (17)O μ-oxo hyperfine coupling of the di-μ-oxo di-Mn(III,IV) bipyridine model (Usov, O. M.; Grigoryants, V. M.; Tagore, R.; Brudvig, G. W.; Scholes, C. P. J. Am. Chem. Soc. 2007, 129, 11886-11887), this signal was assigned to μ-oxo oxygen. EPR line broadening was obvious from this (17)O μ-oxo species. Earlier exchange proceeded on the minute or faster time scale into a non-μ-oxo position, from which (17)O ENDOR showed a smaller 3.8 MHz hyperfine coupling and possible quadrupole splittings, indicating a terminal water of Mn(III). Exchangeable proton/deuteron hyperfine couplings, consistent with terminal water ligation to Mn(III), also appeared. Q-band CW ENDOR from the S(2) state of the OEC was obtained following multihour (17)O exchange, which showed a (17)O hyperfine signal with a 11 MHz hyperfine coupling, tentatively assigned as μ-oxo-(17)O by resemblance to the μ-oxo signals from Mn catalase and the di-μ-oxo di-Mn(III,IV) bipyridine model.

Design Challenges and Guidelines for Persuasive Technologies that Facilitate Healthy Lifestyles

Many diseases and health risks are the result of unhealthy lifestyles and technology could be used as an intervention. However, designing healthy lifestyle technologies is challenging, as the technology should be able to influence user behavior. In this case study, the design and evaluation process of a persuasive healthy lifestyle assistance technology was investigated. The iterative design and evaluation process included: contextual inquiry, storyboarding, concept generation, paper prototyping, video prototyping, interactive prototyping and user testing. Several design challenges are identified and guidelines are described for designing a technological intervention to encourage healthy lifestyles.

P3-13-09: Impact of Estrogen Receptor Negativity on Clinical Outcomes Following Accelerated Partial Breast Irradiation

Purpose: To determine the impact of estrogen receptor (ER) negativity on clinical outcomes for patients treated with Accelerated Partial Breast Irradiation (APBI).

Materials/Methods(s): We evaluated 506 consecutive patients treated with interstitial brachytherapy (n= 199), balloon-based brachytherapy (n=203), and 3D-CRT (n=104). ER negative (ERN) status was assigned using the traditional definition of an ER nuclear IHC stain < 10%, which corresponds to an Allred/NSABP staining score of < 2. 63 patients (12.5%) were ER negative and 443 (87.5%) were ER positive (ERP). Patient demographics and clinical outcomes (IBTR, RNF, DM, DFS, CSS, OS) were analyzed for each group.

Results: The two groups had similar patient characteristics. Tumor sizes were slightly larger for the ERN group at 11.9mm vs. 10.7mm, although this was not statistically significant (p=0.14). No differences were seen in median age (63 vs. 64 years, p=0.36), rate of HER-2/neu overexpression (83% vs. 91%, p=0.11), or lymph node positivity (6% vs. 9%, p=0.55) between the ERN vs. ERP groups, respectively. There were an equal distribution of invasive ductal carcinoma (ERN n=55, 87%; ERP n=387, 87%) and DCIS (ERN n=8, 13%; ERP n=56, 13%) patients within each group. The use of chemotherapy (55% vs. 15%, p<0.001) and nuclear grade (71% vs. 12%, p<0.001) were higher in the ERN vs. ERP cohort. With a mean follow up of 6.1 years, the 5-year actuarial rates of ipsilateral breast tumor recurrence (IBTR), regional nodal failure (RNF), and distant metastasis (DM) for the entire cohort were 1.8%, 0.6%, and 3.2%. Although this was not statistically significant, ERN patients appear to have an increased rate of local failure than patients with ERP histology (4.0% vs. 1.5%, p=0.13). Rates of RNF and DM were, however, significantly higher for the ERN group (RNF: 4.9% ERN vs. 0% ERP, p<0.001; DM: 12.1% ERN vs. 2.0% ERP, p<0.001). Although there was no difference in overall survival at six years (86% vs. 90%, p=0.67), we observed a shorter disease-free survival (86.4% vs. 96.5%, p= 0.01) and cause-specific survival (90% vs. 98%, p=0.01) for the ERN vs. ERP groups.

Conclusion: The ER negative phenotype of early-stage breast cancer may have a decreased rate of locoregional control. We observed a higher rate of DM with reduced disease-free and cause-specific survival in ER negative cases, emphasizing the importance of systemic therapy and careful, long-term follow up for these patients. Prospective study of this histologic subtype with a larger cohort of patients is needed to substantiate these findings.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-13-09.

Modeling eye gaze patterns in clinician-patient interaction with lag sequential analysis

OBJECTIVE

The aim of this study was to examine whether lag sequential analysis could be used to describe eye gaze orientation between clinicians and patients in the medical encounter. This topic is particularly important as new technologies are implemented into multiuser health care settings in which trust is critical and nonverbal cues are integral to achieving trust. This analysis method could lead to design guidelines for technologies and more effective assessments of interventions.

BACKGROUND

Nonverbal communication patterns are important aspects of clinician-patient interactions and may affect patient outcomes.

METHOD

The eye gaze behaviors of clinicians and patients in 110 videotaped medical encounters were analyzed using the lag sequential method to identify significant behavior sequences. Lag sequential analysis included both event-based lag and time-based lag.

RESULTS

Results from event-based lag analysis showed that the patient's gaze followed that of the clinician, whereas the clinician's gaze did not follow the patient's. Time-based sequential analysis showed that responses from the patient usually occurred within 2 s after the initial behavior of the clinician.

CONCLUSION

Our data suggest that the clinician's gaze significantly affects the medical encounter but that the converse is not true.

APPLICATION

Findings from this research have implications for the design of clinical work systems and modeling interactions. Similar research methods could be used to identify different behavior patterns in clinical settings (physical layout, technology, etc.) to facilitate and evaluate clinical work system designs.

Axo-axonal interaction in autonomic regulation of the cerebral circulation

Noradrenaline (NE) and acetylcholine (ACh) released from the sympathetic and parasympathetic neurones in cerebral blood vessels were suggested initially to be the respective vasoconstricting and dilating transmitters. Both substances, however, are extremely weak post-synaptic transmitters. Compelling evidence indicates that nitric oxide (NO) which is co-released with ACh from same parasympathetic nerves is the major transmitter for cerebral vasodilation, and its release is inhibited by ACh. NE released from the sympathetic nerve, acting on presynaptic β2-adrenoceptors located on the neighbouring parasympathetic nitrergic nerves, however, facilitates NO release with enhanced vasodilation. This axo-axonal interaction mediating NE transmission is supported by close apposition between sympathetic and parasympathetic nerve terminals, and has been shown in vivo at the base of the brain and the cortical cerebral circulation. This result reveals the physiological need for increased regional cerebral blood flow in 'fight-or-flight response' during acute stress. Furthermore, α7- and α3β2-nicotinic ACh receptors (nAChRs) on sympathetic nerve terminals mediate release of NE, leading to cerebral nitrergic vasodilation. α7-nAChR-mediated but not α3β2-nAChR-mediated cerebral nitrergic vasodilation is blocked by β-amyloid peptides (Aβs). This may provide an explanation for cerebral hypoperfusion seen in patients with Alzheimer's disease. α7- and α3β2-nAChR-mediated nitrergic vasodilation is blocked by cholinesterase inhibitors (ChEIs) which are widely used for treating Alzheimer's disease, leading to possible cerebral hypoperfusion. This may contribute to the limitation of clinical use of ChEIs. ChEI blockade of nAChR-mediated dilation like that by Aβs is prevented by statins pretreatment, suggesting that efficacy of ChEIs may be improved by concurrent use of statins.

Probing the mechanisms of chronotype using quantitative modeling

The physiological mechanisms underlying interindividual differences in chronotype have yet to be established, although evidence suggests both circadian and homeostatic processes are involved. A physiologically based model is developed by combining models of the sleep-wake switch and circadian pacemaker, providing a means of examining how interactions between these systems affect chronotype. Specifically, chronotype is shown to depend on the relative influences of homeostatic and circadian drives, with a stronger homeostatic drive causing morningness. Changes to intrinsic circadian and homeostatic properties, including homeostatic clearance and production rates, and circadian period and amplitude, are also shown to affect chronotype. These results provide a framework for explaining several experimentally observed phenomena, including age-related morningness, adolescent eveningness, and familial advanced and delayed sleep-phase disorders. Additionally, experimental studies have shown that healthy adults on the extremes of the morningness-eveningness spectrum fall into two subtypes: those whose circadian phase markers are unaffected by chronotype, and those whose circadian phase markers track their chronotype. The model demonstrates that this spectrum likely results from interindividual differences in homeostatic kinetics in the first group, and differences in circadian period in the second group. Physiologically based modeling can thus guide diagnosis of sleep pathologies.

Immunomodulatory activities of a new pentapeptide (Bursopentin) from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is a central immune organ in birds, and some peptides from chicken BF have demonstrated important immune functions. Here, a new 626.27 Da pentapeptide, Bursopentin (BP5, Cys-Lys-Arg-Val-Tyr) was isolated and purified by reverse-phase high-performance liquid chromatography. In this study, we examined the effects of BP5 on antigen-specific immune response in BALB/c mice sensitized with inactivated avian influenza virus (AIV) [A/Duck/Jiangsu/NJ08/05 (AIV H9N2 subtype)]. The results suggested that BP5 enhanced anti-hemagglutinin antibody (IgG, the isotypes IgG1 and IgG2a) production, induced both of Th1- (IL-2 and IFN-γ) and Th2-type (IL-4 and -10) cytokines, increased proliferations of splenic lymphocyte subsets CD4+ T cells (CD3+CD4+), CD8+ T cells (CD3+CD8+) and B cells, and enhanced cytotoxic T-lymphocyte activity of the activated splenocytes against NIH3T3 cells. The effects of BP5 on the proliferation of isolated T- and/or B-cell populations of BALB/c mice were assessed, and the data suggested that BP5 promoted spleen lymphocyte proliferation by activating B cells directly and T cells indirectly. Further analysis revealed that B-lymphocyte proliferation induced by BP5 is mediated by reactive oxygen species generated from thiol auto-oxidation of BP5. Furthermore, our data indicated that protein kinase C, mitogen-activated protein kinase, and nuclear factor kappa B are involved in the signal transductions during the BP5-induced B lymphocyte proliferation. This study indicates that BP5 could be a potential immunomodulator for future immuno-pharmacological use.

Safety and immunogenicity of 2009 pandemic influenza A H1N1 vaccines in China: a multicentre, double-blind, randomised, placebo-controlled trial

BACKGROUND

The current influenza pandemic calls for a safe and effective vaccine. We assessed the safety and immunogenicity of eight formulations of 2009 pandemic influenza A H1N1 vaccine produced by ten Chinese manufacturers.

METHODS

In this multicentre, double-blind, randomised trial, 12 691 people aged 3 years or older were recruited in ten centres in China. In each centre, participants were stratified by age and randomly assigned by a random number table to receive one of several vaccine formulations or placebo. The study assessed eight formulations: split-virion formulation containing 7.5 microg, 15 microg, or 30 microg haemagglutinin per dose, with or without aluminium hydroxide adjuvant, and whole-virion formulation containing 5 microg or 10 microg haemagglutinin per dose, with adjuvant. All formulations were produced from the reassortant strain X-179A (A/California/07/2009-A/PR/8/34). We analysed the safety (adverse events), immunogenicity (geometric mean titre [GMT] of haemagglutination inhibition antibody), and seroprotection (GMT >or=1:40) of the formulations. Analysis was by per protocol. Two sites registered their trial with ClinicalTrials.gov, numbers NCT00956111 and NCT00975572. The other eight studies were registered with the State Food and Drug Administration of China.

FINDINGS

12 691 participants received the first dose on day 0, and 12 348 participants received the second dose on day 21. The seroprotection rate 21 days after the first dose of vaccine ranged from 69.5% (95% CI 65.9-72.8) for the 7.5 microg adjuvant split-virion formulation to 92.8% (91.9-93.6) for the 30 microg non-adjuvant split-virion formulation. The seroprotection rate was 86.5% (796 of 920; 84.1-88.7) in recipients of one dose of the 7.5 microg non-adjuvant split-virion vaccine compared with 9.8% (140 of 1432; 8.3-11.4) in recipients of placebo (p<0.0001). One dose of the 7.5 microg non-adjuvant split-virion vaccine induced seroprotection in 178 of 232 children (aged 3 years to <12 years; 76.7%, 70.7-82.0), 211 of 218 adolescents (12 years to <18 years; 96.8%, 93.5-98.7), 289 of 323 adults (18-60 years; 89.5%, 85.6-92.6), and 118 of 147 adults older than 60 years (80.3%, 72.9-86.4), meeting the European Union's licensure criteria for seroprotection in all age-groups. In children, a second dose of the 7.5 microg formulation increased the seroprotection rate to 97.7% (215 of 220, 94.8-99.3). Adverse reactions were mostly mild or moderate, and self-limited. Severe adverse effects occurred in 69 (0.6%, 0.5-0.8) recipients of vaccine compared with one recipient (0.1%, 0-0.2) of placebo. The most common severe adverse reaction was fever, which occurred in 25 (0.22%; 0.14-0.33) recipients of vaccine after the first dose and four (0.04%; 0.01-0.09) recipients of vaccine after the second dose compared with no recipients of placebo after either dose.

INTERPRETATION

One dose of non-adjuvant split-virion vaccine containing 7.5 microg haemagglutinin could be promoted as the formulation of choice against 2009 pandemic influenza A H1N1 for people aged 12 years or older. In children (aged <12 years), two 7.5 mug doses might be needed.

FUNDING

Sinovac Biotech, Hualan Biological Bacterin, China National Biotec Group, Beijing Tiantan Biological Products, Changchun Institute of Biological Products, Changchun Changsheng Life Sciences, Jiangsu Yanshen Biological Technology Stock, Zhejiang Tianyuan Bio-Pharmaceutical, Lanzhou Institute of Biological Products, Shanghai Institute of Biological Products, and Dalian Aleph Biomedical.

Space charge effects in field emission nanodevices

Electron field emission from a single nanoemitter is a barrier tunneling, quantum mechanical process that can, therefore, be described by the well-known Fowler-Nordheim (FN) equation. At high emission current densities, however, the space charge caused by the cathode may affect the current density-voltage (J-V) characteristics predicted by the FN theory. In this study, we theoretically investigated the effect of space charge on FE nanodevices, including diode and triode structures. The J-V characteristics of FE nanodevices were obtained by analytically (diode structures) or numerically (triode structures) solving the coupled FN equation and Poisson's equation. We discuss the behavior of FE nanodiodes and nanotriodes displaying different geometries, dimensions and work functions of their emitter materials. In the high current density region, space charge plays an important role in FE nanodevices; the threshold current density of space-charge limitation is related to the electric field distributions. Besides, our theoretical results are in good agreement with the experimental results reported previously.

Phase I/II study evaluating early tolerance in breast cancer patients undergoing accelerated partial breast irradiation treated with MammoSite balloon breast brachytherapy catheter using a two-day dose schedule

Abstract #5131

Purpose: Initial phase I/II results utilizing balloon brachytherapy to deliver accelerated partial breast irradiation (APBI) in only 2-days in patients with early stage breast cancer are presented.&#x2028; Materials and Methods: From 3/2004 – 8/2007, 45 patients received adjuvant radiation therapy after lumpectomy with balloon brachytherapy in a phase I/II trial delivering 2800 cGy in 4 fractions of 700 cGy to a depth of 1 cm from the applicator surface. Inclusion criteria for the protocol included: (1) patient age &gt; 40 years, (2) pathological confirmation of stage 0/I/II breast carcinoma, (3) &gt; 3 cm tumor size, (4) &lt; 3 pathologically positive lymph nodes, and (5) negative margins (per NSABP criteria). Toxicities were evaluated using the NCI CTAE v3.0 scale and cosmesis (Harvard Criteria) was documented at &gt; 6 months.&#x2028; Results: The median age was 66 years (48-83) and median skin spacing was 12 mm (8-24). The median follow-up was 11.4 months (5.4-48 mo) with 20 patients (44%) followed greater than one year, 11 (24%) greater than 2 years and 6 (13%) greater than 3 years. At &lt; 6 mo (n=45), grade II toxicity rates were 9% radiation dermatitis (n=4), 13% breast pain (n=6), 2% edema (n=1), and 2% hyperpigmentation (n=1). Grade III breast pain was reported in 13% (n=6). At &gt; 6 months (n=43), grade II radiation dermatitis, induration, and hypopigmentation were 2% (n=1), grade III breast pain was reported in 2% (n=1). Infection was 16% (n=7) at &lt; 6 mo and 2% (n=1) at &gt; 6 mo. Of these pts, only 4% (n=2) had a positive culture, whereas the others were treated empirically due to brisk erythema. Persistent seroma &gt; 6 months was 30% (n=13). FN was seen in 9% (n=4), but only 1 pt required treatment. Rib fracture was seen in 5% (n=2). Cosmesis was good/excellent in 96% and fair in 4%.&#x2028; Conclusions: Treatment with balloon brachytherapy using a 2-day dose schedule resulted acceptable rates of grade II/III chronic toxicity rates and similar cosmetic results observed with standard 5-day APBI schedule.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5131.

Synthesis design of artificial magnetic metamaterials using a genetic algorithm

In this article, we present a genetic algorithm (GA) as one branch of artificial intelligence (AI) for the optimization-design of the artificial magnetic metamaterial whose structure is automatically generated by computer through the filling element methodology. A representative design example, metamaterials with permeability of negative unity, is investigated and the optimized structures found by the GA are presented. It is also demonstrated that our approach is effective for the synthesis of functional magnetic and electric metamaterials with optimal structures. This GA-based optimization-design technique shows great versatility and applicability in the design of functional metamaterials.

Low-loss propagation in Cr4+:YAG double-clad crystal fiber fabricated by sapphire tube assisted CDLHPG technique

Cr4+:YAG double-clad crystal fiber with an uniform 10-microm core was fabricated by using a sapphire tube as a heat capacitor to stabilize the power fluctuation of the CO2 laser in the co-drawing laser-heated pedestal growth system. The uniformity of the fiber core showed a factor of 3 improvement compared to that without the use of sapphire tube. The variation of the core diameter is within the +/-1.35-degree adiabatic criterion and has a autocorrelation length of 1.7 mm. The measured propagation loss is only 0.02 dB/cm. The sapphire tube also reduces the vertical temperature gradient during the crystal fiber growth process so the 10-microm crystal core exhibits a smooth perimeter. The sapphire tube assisted system can be applied to the growth of many other optical crystal materials.

A novel network module for medical devices

In order to allow medical devices to upload the vital signs to a server on a network without manually configuring for end-users, a new network module is proposed. The proposed network module, called Medical Hub (MH), functions as a bridge to fetch the data from all connecting medical devices, and then upload these data to the server. When powering on, the MH can immediately establish network configuration automatically. Network Address Translation (NAT) traversal is also supported by the MH with the UPnP Internet Gateway Device (IGD) methodology. Besides the network configuration, other configuration in the MH is automatically established by using the remote management protocol TR-069. On the other hand, a mechanism for updating software automatically according to the variant connected medical device is proposed. With this mechanism, newcome medical devices can be detected and supported by the MH without manual operation.

Optimal design of integrally gated CNT field-emission devices using a genetic algorithm

A method to optimize the focusing quality of integrally gated CNT field-emission (FE) devices by combining field-emission modeling and a computational intelligence technique, genetic algorithm (GA), is proposed and demonstrated. In this work, the e-beam shape, as a characteristic parameter of electron-optical properties, is calculated by field-emission simulation modeling. Using a design tool that combines GA and physical modeling, a set of structural and electrical parameters for four FE device groups, including double-gate, triple-gate, quadruple-gate and quintuple-gate type, were optimized. The resultant FE devices exhibit satisfactory e-beam focusabilities and the extracted parameters with the best performance for each type of FE device were represented to be fabricated by a VLSI technique. The GA-based automatic design parameter extraction will significantly benefit the design of integrated electron-optical systems for versatile vacuum micro- and nano-electronic applications.

Improved field emission properties of thiolated multi-wall carbon nanotubes on a flexible carbon cloth substrate

In this paper we report the observation of enhanced field emission properties from thiolated multi-wall carbon nanotubes (MWCNTs) produced by a simple and effective two-step chemical surface modification technique. This technique implements carboxylation and thiolation on the MWCNTs synthesized by microwave plasma chemical vapor deposition (MPCVD) on the flexible carbon cloth substrate. The resulting thiolated MWCNTs were found to have a very low threshold field value of 1.25 V µm(-1) and a rather high field enhancement factor of 1.93 × 10(4), which are crucial for applications in versatile vacuum microelectronics.

Depression and Somatic Symptoms within the Farming Community

The relationship between somatic symptoms and depression was investigated in a population of farm operators and their spouses. The sample consisted of principal farm operators and their spouses from northeastern Colorado. There were a total of 709 participants who completed data relevant for our analyses. Exploratory and confirmatory factor analyses were conducted on the symptom inventory, and suggested a two-factor structure. One of the factors consisted of symptoms of a psychological nature, and the other consisted of physical symptoms. While both of the factors were significantly correlated with depression, the factor with psychological items was more strongly related to depression. Gender differences in the symptom factor structure were investigated, and only a few minor differences were found. Gender differences in relationships between the somatic symptom factors and depression were also investigated and were not found. Implications for farm operators, spouses, and rural healthcare providers were discussed.

An unexpected bonding interaction between dxy and a1u orbitals mediated by porphyrin deformation

Through density functional calculation and NMR spectroscopy, an unusual intermediate-spin electronic structure (d(xz)d(yz))3(d(xy))1(d(z)2)1 has been assigned to the six-coordinate saddled [Fe(OETPP)(THF)2]+ complex instead of the corresponding ruffled [Fe(TiPrP)(THF)2]+ complex.

Mixed cystic gliosarcoma and primitive neuroectodermal tumor: a case report

The clinical and pathologic features of a mixed (composite) gliosarcoma and primitive neuroectodermal tumor occurring in a 54-year-old male are presented. A large cyst and the presence of Rosenthal fibers are also unusual features of this tumor. To our knowledge, such a morphologically variegated tumor has not previously been reported.

The prevalence and spectrum of alpha and beta thalassaemia in Guangdong Province: implications for the future health burden and population screening

AIM

Thalassaemia is a good candidate disease for control by preventive genetic programmes in developing countries. Accurate population frequency data are needed for planning the control of thalassaemia in the high risk Guangdong Province of southern China.

METHODS

In total, 13397 consecutive samples from five geographical areas of Guangdong Province were analysed for both haematological and molecular parameters.

RESULTS

There was a high prevalence of carriers of alpha thalassaemia (8.53%), beta thalassaemia (2.54%), and both alpha and beta thalassaemia (0.26%). Overall, 11.07% of the population in this area were heterozygous carriers of alpha and beta thalassaemia. The mutation spectrum of alpha and beta thalassaemia and its constitution were fully described in this area. This study reports the true prevalence of silent alpha thalassaemia in the southern China population for the first time. In addition, two novel mutations that give rise to alpha thalassaemia, one deletion resulting in beta thalassaemia, and a rare deletion (--(THAI) allele) previously unreported in mainland China were detected. The frequency of the most common mutation, the Southeast Asian type of deletion (--(SEA), accounting for 48.54% of all alpha thalassaemias) was similar to the total of two alpha(+) thalassaemia deletions (-alpha(3.7) and -alpha(4.2), accounting for 47.49% of alpha thalassaemia).

CONCLUSION

Both alpha and beta thalassaemia are widely distributed in Guangdong Province of China. The knowledge gained in this study will enable the projected number of pregnancies at risk to be estimated and a screening strategy for control of thalassaemia to be designed in this area.

Cardiac complications of enterovirus rhombencephalitis

BACKGROUND

Epidemics of enterovirus 71 infection have caused the death of many children throughout the world. Rhombencephalitis, brain stem encephalitis, and heart failure were present in all of the fatal cases. However, no evidence of myocarditis was noted in the heart specimens, and the mechanism of heart failure remains unknown.

AIMS

To characterise the presentation of cardiac complications in children with enterovirus rhombencephalitis and discuss its pathogenesis.

METHODS

Ninety one consecutive patients with enterovirus rhombencephalitis underwent echocardiography. Of these, 17 patients (nine male, eight female; median age 14 months, range 4-57 months) with left ventricular dysfunction were studied.

RESULTS

Tachycardia was noted in all patients and systemic hypertension in 12. Muscle-brain fraction of creatine kinase was >5% in 14 patients. Plasma norepinephrine and epinephrine levels were significantly raised in the three patients in whom these were analysed. Electrocardiographic abnormalities were noted in eight patients. Pulmonary oedema was complicated in 15 patients. The initial ejection fraction of the left ventricle was 22-58% (mean 37%, SD 11%). All patients deteriorated to hypotensive shock within 12 hours and 13 died. Heart specimens from seven patients showed no evidence of myocarditis, but significant coagulative myocytolysis, myofibrillar degeneration, and cardiomyocyte apoptosis were observed.

CONCLUSIONS

Acute heart failure was noted in 19% of patients with enterovirus rhombencephalitis, which had a fatality rate of 77%. It was not caused by myocarditis but possibly by neurogenic cardiac damage.

Symmetry and bonding in metalloporphyrins. A modern implementation for the bonding analyses of five- and six-coordinate high-spin iron(III)-porphyrin complexes through density functional calculation and NMR spectroscopy

Bonding interactions between the iron and the porphyrin macrocycle of five- and six-coordinate high-spin iron(III)-porphyrin complexes are analyzed within the framework of approximate density functional theory with the use of the quantitative energy decomposition scheme in combination with removal of the vacant pi orbitals of the porphyrin from the valence space. Although the relative extent of the iron-porphyrin interactions can be evaluated qualitatively through the spin population and orbital contribution analyses, the bond strengths corresponding to different symmetry representations can be only approximated quantitatively by the orbital interaction energies. In contrast to previous suggestions, there are only limited Fe --> P pi back-bonding interactions in high-spin iron(III)-porphyrin complexes. It is the symmetry-allowed bonding interaction between d(z)2 and a(2u) orbitals that is responsible for the positive pi spin densities at the meso-carbons of five-coordinate iron(III)-porphyrin complexes. Both five- and six-coordinate complexes show significant P --> Fe pi donation, which is further enhanced by the movement of the metal toward the in-plane position for six-coordinate complexes. These bonding characteristics correlate very well with the NMR data reported experimentally. The extraordinary bonding interaction between d(z)2 and a(2u) orbitals in five-coordinate iron(III)-porphyrin complexes offers a novel symmetry-controlled mechanism for spin transfer between the axial ligand sigma system and the porphyrin pi system and may be critical to the electron transfer pathways mediated by hemoproteins.

Causal inference on the difference of the restricted mean lifetime between two groups

When comparing survival times between two treatment groups, it may be more appropriate to compare the restricted mean lifetime, i.e., the expectation of lifetime restricted to a time L, rather than mean lifetime in order to accommodate censoring. When the treatments are not assigned to patients randomly, as in observational studies, we also need to account for treatment imbalances in confounding factors. In this article, we propose estimators for the difference of the restricted mean lifetime between two groups that account for treatment imbalances in prognostic factors assuming a proportional hazards relationship. Large-sample properties of our estimators based on martingale theory for counting processes are also derived. Simulation studies were conducted to compare these estimators and to assess the adequacy of the large-sample approximations. Our methods are also applied to an observational database of acute coronary syndrome patients from Duke University Medical Center to estimate the treatment effect on the restricted mean lifetime over 5 years.

The role of a beta-bulge in the folding of the beta-hairpin structure in ubiquitin

It is known that the peptide corresponding to the N-terminal beta-hairpin of ubiquitin, U(1-17), can populate the monomeric beta-hairpin conformation in aqueous solution. In this study, we show that the Gly-10 that forms the bulge of the beta-turn in this hairpin is very important to the stability of the hairpin. The deletion of this residue to desG10(1-16) unfolds the structure of the peptide in water. Even under denaturing conditions, this bulge appears to be important in maintaining the residual structure of ubiquitin, which involves tertiary interactions within the sequence 1 to 34 in the denatured state. We surmise that this residual structure functions as one of the nucleation centers in the folding process and is important in stabilizing the transition state. In accordance with this idea, deleting Gly-10 slows down the refolding and unfolding rate by about one half.

Effects of turn residues in directing the formation of the beta-sheet and in the stability of the beta-sheet

The designed peptide (denoted 20-mer, sequence VFITS(D)PGKTYTEV(D)PGOKILQ) has been shown to form a three-strand antiparallel beta-sheet. It is generally believed that the (D)Pro-Gly segment has the propensity to adopt a type II' beta-turn, thereby promoting the formation of this beta-sheet. Here, we replaced (D)Pro-Gly with Asp-Gly, which should favor a type I' turn, to examine the influence of different type of turns on the stability of the beta-sheet. Contrary to our expectation, the mutant peptide, denoted P6D, forms a five-residue type I turn plus a beta-bulge between the first two strands due to a one amino-acid frameshift in the hydrogen bonding network and side-chain inversion of the first beta-strand. In contrast, the same kind of substitution at (D)Pro-14 in the double mutant, denoted P6DP14D, does not yield the same effect. These observations suggest that the SDGK sequence disfavors the type I' conformation while the VDGO sequence favors a type I' turn, and that the frameshift in the first strand provides a way for the peptide to accommodate a disfavored turn sequence by protruding a bulge in the formation of the beta-hairpin. Thus, different types of turns can affect the stability of a beta-structure.

Intraocular lens implantation after penetrating keratoplasty

PURPOSE

We evaluated the clinical results of nonsimultaneous penetrating keratoplasty, cataract extraction, and intraocular lens (IOL) implantation (two-stage surgery) for combined corneal disease and cataract.

METHODS

Twenty-six eyes of 24 patients with an average age of 46 years who underwent two-stage surgery were studied retrospectively. Variables included visual acuity, refractive status, specular microscopy before and after IOL implantation (6 months), and the occurrence of graft failure. Astigmatism was corrected by suture removal and relaxing incision. The mean follow-up after IOL placement was 16 months.

RESULTS

Unaided visual acuity was 20/100 or better in 22 (83%) eyes after the second procedure. Twenty-one (81%) eyes had an aided visual acuity of at least 20/40. The mean refractive and absolute errors were -1.49 +/- 1.39 diopters (D) and 1.55 +/- 1.30 D, respectively. The mean keratometric and refractive cylinders were 3.50 D and 2.26 D, respectively. Nineteen (73%) eyes had a spherical equivalent refraction within 2 D of emmetropia. Anisometropia (> or =3 D) occurred in four (15%) eyes. The endothelial cell density, the coefficient of variation, and the percentage of hexagonal cells documented by specular microscopy were not significantly different before and after IOL implantation. Complications included three rejections, two cases of herpetic recurrence, and one late decompensation. Two graft failures (8%) occurred after secondary surgery.

CONCLUSION

The two-stage surgery is a safe and effective modality.