BigSMARTS: A Topologically Aware Query Language and Substructure Search Algorithm for Polymer Chemical Structures

Molecular search is important in chemistry, biology, and informatics for identifying molecular structures within large data sets, improving knowledge discovery and innovation, and making chemical data FAIR (findable, accessible, interoperable, reusable). Search algorithms for polymers are significantly less developed than those for small molecules because polymer search relies on searching by polymer name, which can be challenging because polymer naming is overly broad (i.e., polyethylene), complicated for complex chemical structures, and often does not correspond to official IUPAC conventions. Chemical structure search in polymers is limited to substructures, such as monomers, without awareness of connectivity or topology. This work introduces a novel query language and graph traversal search algorithm for polymers that provides the first search method able to fully capture all of the chemical structures present in polymers. The BigSMARTS query language, an extension of the small-molecule SMARTS language, allows users to write queries that localize monomer and functional group searches to different parts of the polymer, like the middle block of a triblock, the side chain of a graft, and the backbone of a repeat unit. The substructure search algorithm is based on the traversal of graph representations of the generating functions for the stochastic graphs of polymers. Operationally, the algorithm first identifies cycles representing the monomers and then the end groups and finally performs a depth-first search to match entire subgraphs. To validate the algorithm, hundreds of queries were searched against hundreds of target chemistries and topologies from the literature, with approximately 440,000 query-target pairs. This tool provides a detailed algorithm that can be implemented in search engines to provide search results with full matching of the monomer connectivity and polymer topology.

Community Resource for Innovation in Polymer Technology (CRIPT): A Scalable Polymer Material Data Structure

The Community Resource for Innovation in Polymer Technology (CRIPT) data model is designed to address the high complexity in defining a polymer structure and the intricacies involved with characterizing material properties.

Canonicalizing BigSMILES for Polymers with Defined Backbones

BigSMILES, a line notation for encapsulating the molecular structure of stochastic molecules such as polymers, was recently proposed as a compact and readable solution for writing macromolecules. While BigSMILES strings serve as useful identifiers for reconstructing the molecular connectivity for polymers, in general, BigSMILES allows the same polymer to be codified into multiple equally valid representations. Having a canonicalization scheme that eliminates the multiplicity would be very useful in reducing time-intensive tasks like structural comparison and molecular search into simple string-matching tasks. Motivated by this, in this work, two strategies for deriving canonical representations for linear polymers are proposed. In the first approach, a canonicalization scheme is proposed to standardize the expression of BigSMILES stochastic objects, thereby standardizing the expression of overall BigSMILES strings. In the second approach, an analogy between formal language theory and the molecular ensemble of polymer molecules is drawn. Linear polymers can be converted into regular languages, and the minimal deterministic finite automaton uniquely associated with each prescribed language is used as the basis for constructing the unique text identifier associated with each distinct polymer. Overall, this work presents algorithms to convert linear polymers into unique structure-based text identifiers. The derived identifiers can be readily applied in chemical information systems for polymers and other polymer informatics applications.

Extending BigSMILES to Non-Covalent Bonds in Supramolecular Polymer Assemblies

As a machine-recognizable representation of polymer connectivity, BigSMILES line notation extends SMILES from deterministic to stochastic structures. The same framework that allows BigSMILES to accommodate stochastic covalent connectivity can be extended to non-covalent bonds, enhancing its value for polymers, supramolecular materials, and colloidal chemistry. Non-covalent bonds are captured through the inclusion of annotations to pseudo atoms serving as complementary binding pairs, minimal key/value pairs to elaborate other relevant attributes, and indexes to specify the pairing among potential donors and acceptors or bond delocalization. Incorporating these annotations into BigSMILES line notation enables the representation of four common classes of non-covalent bonds in polymer science: electrostatic interactions, hydrogen bonding, metal–ligand complexation, and π–π stacking. The principal advantage of non-covalent BigSMILES is the ability to accommodate a broad variety of non-covalent chemistry with a simple user-orientated, semi-flexible annotation formalism. This goal is achieved by encoding a universal but non-exhaustive representation of non-covalent or stochastic bonding patterns through syntax for (de)protonated and delocalized state of bonding as well as nested bonds for correlated bonding and multi-component mixture. By allowing user-defined descriptors in the annotation expression, further applications in data-driven research can be envisioned to represent chemical structures in many other fields, including polymer nanocomposite and surface chemistry.

Non-covalent BigSMILES enables the representation of donor/acceptor interactions and delocalized bonds for polymer assemblies.

Random Forest Predictor for Diblock Copolymer Phase Behavior

Physics-based models are the primary approach for modeling the phase behavior of block copolymers. However, the successful use of self-consistent field theory (SCFT) for designing new materials relies on the correct chemistry- and temperature-dependent Flory-Huggins interaction parameter χ_AB that quantifies the incompatibility between the two blocks A and B as well as accurate estimation of the ratio of Kuhn lengths (b_A/b_B) and block densities. This work uses machine learning to model the phase behavior of AB diblock copolymers by using the chemical identities of blocks directly, obviating the need for measurement of χ_AB and b_A/b_B. The random forest approach employed predicts the phase behavior with almost 90% accuracy after training on a data set of 4768 data points, almost twice the accuracy obtained using SCFT employing χ_AB from group contribution theory. The machine-learning model is notably sensitive toward the uncertainty in measuring molecular parameters; however, its accuracy still remains at least 60% even for highly uncertain experimental measurements. Accuracy is substantially reduced when extrapolating to chemistries outside the training set. This work demonstrates that a random forest phase predictor performs remarkably well in many scenarios, providing an opportunity to predict self-assembly without measurement of molecular parameters.

PolyDAT: A Generic Data Schema for Polymer Characterization

Polymers are stochastic materials that represent distributions of different molecules. In general, to quantify the distribution, polymer researchers rely on a series of chemical characterizations that each reveal partial information on the distribution. However, in practice, the exact set of characterizations that are carried out, as well as how the characterization data are aggregated and reported, is largely nonstandard across the polymer community. This scenario makes polymer characterization data highly disparate, thereby significantly slowing down the development of polymer informatics. In this work, a proposal on how structural characterization data can be organized is presented. To ensure that the system can apply universally across the entire polymer community, the proposed schema, PolyDAT, is designed to embody a minimal congruent set of vocabulary that is common across different domains. Unlike most chemical schemas, where only data pertinent to the species of interest are included, PolyDAT deploys a multi-species reaction network construct, in which every characterization on relevant species is collected to provide the most comprehensive profile on the polymer species of interest. Instead of maintaining a comprehensive list of available characterization techniques, PolyDAT provides a handful of generic templates, which align closely with experimental conventions and cover most types of common characterization techniques. This allows flexibility for the development and inclusion of new measurement methods. By providing a standard format to digitalize data, PolyDAT serves not only as an extension to BigSMILES that provides the necessary quantitative information but also as a standard channel for researchers to share polymer characterization data.

BigSMILES: A Structurally-Based Line Notation for Describing Macromolecules

Having a compact yet robust structurally based identifier or representation system is a key enabling factor for efficient sharing and dissemination of research results within the chemistry community, and such systems lay down the essential foundations for future informatics and data-driven research. While substantial advances have been made for small molecules, the polymer community has struggled in coming up with an efficient representation system. This is because, unlike other disciplines in chemistry, the basic premise that each distinct chemical species corresponds to a well-defined chemical structure does not hold for polymers. Polymers are intrinsically stochastic molecules that are often ensembles with a distribution of chemical structures. This difficulty limits the applicability of all deterministic representations developed for small molecules. In this work, a new representation system that is capable of handling the stochastic nature of polymers is proposed. The new system is based on the popular "simplified molecular-input line-entry system" (SMILES), and it aims to provide representations that can be used as indexing identifiers for entries in polymer databases. As a pilot test, the entries of the standard data set of the glass transition temperature of linear polymers (Bicerano, 2002) were converted into the new BigSMILES language. Furthermore, it is hoped that the proposed system will provide a more effective language for communication within the polymer community and increase cohesion between the researchers within the community.

Counting Secondary Loops Is Required for Accurate Prediction of End-Linked Polymer Network Elasticity

To predict and understand the properties of polymer networks, it is necessary to quantify network defects. Of the various possible network defects, loops are perhaps the most pervasive and yet difficult to directly measure. Network disassembly spectrometry (NDS) has previously enabled counting of the simplest loops-primary loops-but higher-order loops, e.g., secondary loops, have remained elusive. Here, we report that the introduction of a nondegradable tracer within the NDS framework enables the simultaneous measurement of primary and secondary loops in end-linked polymer networks for the first time. With this new "NDS2.0" method, the concentration dependences of the primary and secondary loop fractions are measured; the results agree well with a purely topological theory for network formation from phantom chains. In addition, semibatch monomer addition is shown to decrease both primary and secondary loops, though the latter to a much smaller extent. Finally, using the measured primary and secondary loop fractions, we were able to predict the shear storage modulus of end-linked polymer gels via real elastic network theory (RENT).

Kinetic Monte Carlo Simulation for Quantification of the Gel Point of Polymer Networks

Accurate prediction of the gel point for real polymer networks is a long-standing challenge in polymer chemistry and physics that is extremely important for applications of gels and elastomers. Here, kinetic Monte Carlo simulation is applied to simultaneously describe network topology and growth kinetics. By accounting for topological defects in the polymer networks, the simulation can quantitatively predict experimental gel point measurements without any fitting parameters. Gel point suppression becomes more severe as the primary loop fraction in the networks increases. A topological homomorphism theory mapping defects onto effective junctions is developed to qualitatively explain the origins of this effect, which accurately captures the gel point suppression in the low loop limit where cooperative effects between topological defects are small.

Cardiac autonomic function and insulin resistance for the development of hypertension: a six-year epidemiological follow-up study

BACKGROUND AND AIMS

To explore the impact of cardiac autonomic function (CAF) and insulin resistance (IR) on incident hypertension.

METHODS AND RESULTS

In 1996, 1638 subjects finished baseline examination, which included anthropometry, blood pressures, CAF, blood biochemistry, plasma insulin, urine examination and electrocardiogram. CAF included standard deviation of normal-to-normal intervals or RR intervals (SDNN), low- and high-frequency power spectrum (LF and HF), and LF/HF ratio at supine for 5 min, the RR interval changes during lying-to-standing maneuver, and the ratio between the longest RR interval during expiration and the shortest RR interval during inspiration (E/I ratio). We used homeostasis model assessment to define beta cell function (HOMA-B) and insulin resistance (HOMA-IR). In total, 992 non-hypertensive participants completed the follow-up assessment in 2003 and 959 participants were included for the final analysis. Incident hypertension was determined by blood pressure status at follow-up. In unadjusted model, both square root of HOMA-IR (OR:3.37, 95%CI: 2.10-6.64) and HOMA-B (OR:0.996, 95%CI: 0.992-0.999) were related to incident hypertension. In multivariate model, square root of HOMA-IR (OR:1.97, 95%CI: 1.05-3.70), but not HOMA-B, was associated with incident hypertension. After further adjustment for baseline CAF, the positive relationship between the square root of HOMA-IR and incident hypertension disappeared. In contrast, LF/HF ratio (OR:1.18, 95%CI: 1.01-1.37), HF power (OR:0.98, 95%CI: 0.96-0.999), and E/I ratio (OR:0.71, 95%CI: 0.54-0.95) were each independently associated with incident hypertension after further adjustment for HOMA measures.

CONCLUSION

Sympathovagal imbalance with an apparently decreased parasympathetic tone is an important predictor of incident hypertension independent of IR.

Seasonal variation and health risk assessment of polycyclic aromatic hydrocarbons in Miaoli city, Taiwan

The ambient PAHs levels in the downtown area of a traditional small city were analyzed for winter and summer seasons. A total of 16 PAHs in gaseous and particulate phase were quantified. The average gaseous PAHs were 2,189 ± 1,194 and 623.8 ± 545.1 ng/m(3) in winter and summer seasons, respectively. For the PAHs in particulate phase, they were 40.32 ± 12.15 and 11.99 ± 5.63 ng/m(3) in winter and summer seasons, respectively. These values were comparable to those reported for large cities or even higher. The estimated BaPeq was 12.32 ± 6.34 ng/m(3). As low-molecular-weight PAHs primarily existed in gaseous phase, high-molecular-weight PAHs in particulate phase became a significant fraction of total particulate phase PAHs. Particulate phase PAHs was significantly inversely associated with the ambient temperature for each individual PAHs species. However, this relationship did not exist for high-molecular-weight PAHs in gaseous phase. The results indicated the photo-degradation of high-molecular-weight PAHs should warrant a further thoughtfully investigation.

Characteristics of polycyclic aromatic hydrocarbon emissions of particles of various sizes from smoldering incense

Release of polycyclic aromatic hydrocarbons (PAHs) in particles of various sizes from smoldering incenses was determined. Among the three types of incense investigated, yielding the total PAH emission rate and factor ranges for PM0.25 were 2,139.7-6,595.6 ng/h and 1,762.2-8,094.9 ng/g, respectively. The PM0.25/PM2.5 ratio of total PAH emission factors and rates from smoldering three incenses was greater than 0.92. This study shows that total particle PAH emission rates and factors were mainly <0.25 μm. Furthermore, the total toxic equivalency emission rates and factors of PAHs for PM0.25 were 241.3-469.7 and 198.8-576.2 ng/g from the three smoldering incenses. The benzo[a]pyrene accounted for 65.2%-68.0% of the total toxic equivalency emission factor of PM2.5 for the three incenses. Experimental results clearly indicate that the PAH emission rates and factors were influenced significantly by incense composition, including carbon and hydrogen content. The study concludes that smoldering incense with low atomic hydrogen/carbon ratios minimized the production of total polycyclic aromatic hydrocarbons of both PM2.5 and PM0.25.

Serious pulmonary toxicity in patients with Hodgkin's lymphoma with SGN-30, gemcitabine, vinorelbine, and liposomal doxorubicin is associated with an FcγRIIIa-158 V/F polymorphism

BACKGROUND

Based on in vitro synergistic cytotoxicity when anti-CD30 antibodies are combined with gemcitabine, the Cancer and Leukemia Group B conducted a double-blind, randomized, phase II trial of SGN-30 with gemcitabine, vinorelbine, and pegylated liposomal doxorubicin (GVD) in patients with relapsed Hodgkin's lymphoma.

PATIENTS AND METHODS

In part 1 of the trial, 16 patients received SGN-30 with GVD to assess the safety of the combination. In part 2, patients were randomly allocated to SGN-30 (n = 7) or placebo (n = 7) with GVD to determine overall response rate (ORR).

RESULTS

ORR in all 30 patients was 63% (65% with SGN-30 plus GVD, n = 23, and 57% with placebo plus GVD, n = 7). Median event-free survival was 9.0 months, with no difference between the two arms. Grades 3-5 pneumonitis occurred in five patients receiving SGN-30 and GVD, leading to premature closure of the trial. All five patients with pulmonary toxicity had a V/F polymorphism in the FcγRIIIa gene (P = 0.008).

CONCLUSIONS

Together with historical data demonstrating a 2% incidence of pulmonary events with GVD, these results indicate that SGN-30 cannot safely be administered concurrently. The risk of pneumonitis with SGN-30 and GVD is greatest in patients with an FcγRIIIa V/F polymorphism.

A phase I/II study of rituximab and etanercept in patients with chronic lymphocytic leukemia and small lymphocytic lymphoma

Rituximab has modest activity in relapsed Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) but is associated with TNF-α release that can cause CLL proliferation and inhibit apoptosis. We examined whether disruption of TNF-α by etanercept improves response to rituximab in CLL. Eligible patients had previously treated CLL with performance status 0–3. Patients received etanercept 25 mg subcutaneously twice weekly (weeks 1–5) and rituximab 375 mg/m² intravenously thrice weekly (weeks 2–5) using a phase I/II design. Primary endpoints were response and toxicity. The 36 enrolled patients had a median of 2 prior treatments; 50% were fludarabine-refractory, and 22% had del(17p13.1). Of the 34 response-evaluable patients, ten (29%) responded, including 9 partial responses and 1 complete remission. Response was not affected by prior rituximab nor fludarabine-refractory status, but no patients with del(17p13.1) responded. Median PFS for responders was 9.0 months (range 1–43). Ten patients have had treatment-free intervals exceeding 12 months, including four who have remained untreated for 32, 43, 46 and 56 months. Adverse events were mild, including mild infusion reactions, transient cytopenias and grade 3 infections in 14%. The combination of etanercept and thrice weekly rituximab produces durable remissions in non-del(17p13.1) CLL patients and is well tolerated.

Alemtuzumab (Campath-1H) in the treatment of chronic lymphocytic leukemia

Alemtuzumab (Campath-1H) is a humanized IgG1 monoclonal antibody that targets the human CD52 antigen. CD52 is expressed by a variety of lymphoid neoplasms and most human mononuclear cell subsets. In 2001, alemtuzumab was approved for marketing in the United States and Europe for use in patients with fludarabine-refractory chronic lymphocytic leukemia (CLL). In heavily pretreated patients with CLL, the overall response rate (ORR) is approximately 35%, and in previously untreated patients the ORR is greater than 80%, with a recent randomized study suggesting it is superior to alkylator-based therapy. Importantly, alemtuzumab is effective in patients with high-risk del(17p13.1) and del(11q22.3) CLL. Alemtuzumab combination studies with fludarabine and/or monoclonal antibodies such as rituximab have demonstrated promising results. Alemtuzumab is also being studied in CLL patients as consolidation therapy for treatment of minimal residual disease, in preparation for stem cell transplantation and to prevent acute and chronic graft versus host disease. Alemtuzumab is frequently associated with acute 'first-dose' reactions when administered intravenously, but is much better tolerated when administered subcutaneously without loss of therapeutic efficacy. Additional potential adverse events associated with alemtuzumab administration include myelosuppression as well as profound cellular immune dysfunction with the associated risk of viral reactivation and other opportunistic infections. Additional studies detailing the mechanism of action of alemtuzumab as well as new strategies for prevention of opportunistic infections will aid in the future therapeutic development of this agent.

Filgrastim and alemtuzumab (Campath-1H) for refractory chronic lymphocytic leukemia

Alemtuzumab (anti-CD52; Campath-1H) is effective in fludarabine-refractory chronic lymphocytic leukemia (CLL), but is associated with infection and early onset neutropenia. To reduce toxicity, filgrastim (G-CSF) was administered concurrently with alemtuzumab. In total, 14 CLL patients (median age 59) with a median of 3.5 prior regimens (range 1--12) received i.v. alemtuzumab, stepped up from 3 to 30 mg the first week, then 30 mg thrice weekly for 12 weeks. Filgrastim 5 microg/kg was administered daily 5 days before and throughout alemtuzumab therapy. Six patients developed cytomegalovirus (CMV) reactivation 3--6 weeks into treatment; six patients developed fever, three neutropenia, and one pneumonia. The patient with CMV pneumonia died; ganciclovir cleared CMV in the other patients. Five patients developed early neutropenia (weeks 2--5). Four patients developed delayed neutropenia (weeks 10--13) unassociated with CMV reactivation. Nine patients ceased therapy because of infectious and hematologic toxicity. Five partial responses were noted, all in patients with lymph nodes>cm, lasting a median of 6.5 months (range 5--13). Filgrastim and alemtuzumab were given concurrently with manageable infusion toxicity and clinical activity, but the efficacy of this regimen was limited by delayed neutropenia of unclear etiology and CMV reactivation. Filgrastrim should not be administered prophylactically during alemtuzumab therapy outside clinical trials.

The Significance of Hepatic Vein Outflow Volume in Hepatic Outflow Insufficiency of Living Right Liver Graft Evaluated by Doppler Ultrasound

The color Doppler ultrasound has been used to evaluate hepatic vein (HV) outflow insufficiency based on flow velocity and waveforms. In our experience, some cases with flat waveforms are clinically asymptomatic. The parameters of HV flow velocity and waveforms are not always correlated with clinical problems. So, we proposed that total HV flow volume (HVFV) may be a more reliable index. From August 2001 to July 2003, 31 cases among 48 adult-to-adult living related transplants of a right liver graft had one HV anastomosis. HV velocity, waveforms, and HVFV were compared both before and after transplantation. We set the minimal HVFV ratio at 80% based on the original HVFV before graft retrieval. There was no significant difference in HVFV before liver graft retrieval between the 2 groups, but there was a significant change after transplantation. There were no cases of HV insufficiency among group A patients (>80%), whose HVFV ranged from 397 to 1181 mL/min with ratios from 75% to 180% (mean 115%). In group B, there were 4 complicated cases with prolonged severe ascites (<80%) with HVFV ratios from 56% to 76% (mean 66%). Fisher exact test showed a great significance (P < .001). Thus the preliminary criteria of 80% minimal HVFV ratio allows detection of HV insufficiency for further interventional management.

Hepatic venous stenosis in partial liver graft transplantation detected by color Doppler ultrasound before and after radiological interventional management

Hepatic outflow insufficiency remains one of the major complications causing postoperative graft failure especially among partial liver graft transplantations (PLT) including living donor liver transplantation (LDLT), reduced size liver transplantation (RLT), and split liver transplantation (SLT). These procedures are different from the whole liver graft transplantations (OLT), which include multiple vascular anastomoses. Color Doppler ultrasound (CDUS) was used to evaluate the hepatic venous outflow from grafts before and after radiological interventional management and to document treatment effects. From June 1994 to March 2003, our 136 cases of PLTs included 131 LDLTs, two RLTs, and three SLTs. Seven cases (six children and one adult) showed postoperative hepatic vein outflow obstruction and persistent massive ascites, as detected by color Doppler ultrasound (CDUS) and confirmed by interventional angiography. The CDUS showed a monophasic flat waveform with a relatively low hepatic vein average peak velocity (Va) in all cases (mean 11 cm/s). Successful interventional procedures included balloon dilatation in three cases and metallic stent replacement in four cases. CDUS was used with guidance during the procedure to confirm restoration of normal hepatic vein flow with a multiphasic waveform and an objective increase of average flow velocity (high to average 66 cm/s). Ascites disappeared dramatically after the procedure. In conclusion CDUS is the prime modality to diagnose and document a treatment response.

Needlescopic thoracic sympathetic block by clipping for craniofacial hyperhidrosis: an analysis of 28 cases

BACKGROUND

Endoscopic thoracic sympathectomy or sympathicotomy of the lower part of the stellate ganglion is an efficient method for the treatment of craniofacial hyperhidrosis, but postoperative compensatory sweating may be troublesome in some patients. Needlescopic thoracic sympathetic block by clipping may achieve a similar effect as well as providing a possible reverse operation for patients who suffer from intolerable postoperative compensatory sweating.

METHODS

Between January 1998 and June 2000, we collected a total of 28 patients with craniofacial hyperhidrosis. There were 15 men and 13 women with a mean age of 39.2 years (ranges, 19-50). All patients were placed under single-lumen intubated anesthesia in a semisitting position. Two ports were needed. We used a 2-mm 0 degrees thoracoscope and endo clips to perform a sympathetic block by clipping the lower third of the stellate ganglion at the second intercostal space.

RESULTS

The operation was usually accomplished within 20 min (ranges, 15-30). All patients were discharged within 4 h after the operation. There were no surgical complications or surgical mortality cases. All patients achieved improvement of craniofacial hyperhidrosis without recurrent symptoms after a mean of 25.3 months (range, 12-41) of follow-up. Twenty-five patients (85.7%) developed compensatory sweating of the trunk and lower limbs. One of these patients could not tolerate this postoperative sweating; he therefore underwent a reverse operation and obtained improvement of the compensatory sweating 18 days after removal of the endo clips.

CONCLUSION

Needlescopic thoracic sympathetic block by clipping is a safe and effective method for the treatment of craniofacial hyperhidrosis; compensatory sweating may be improved after a reverse operation and removal of the endo clips.

Second autologous stem cell transplant for multiply relapsed Hodgkin's disease

Therapeutic options for patients with Hodgkin's disease who relapse after high-dose chemotherapy with autologous stem cell support are limited. Salvage chemotherapy is not curative, and allogeneic stem cell transplantation in this setting is associated with mortality rates of 40-65%. We report our institution's experience with second autologous transplants in this patient population. Five patients (median age 36) with relapsed Hodgkin's disease underwent a second autologous stem cell transplant at a median of 66 months after first transplant. Four patients received CBV, and one patient received BuCy as conditioning. Neutrophil and platelet engraftment occurred by days +10 and +16, respectively. All patients achieved a complete response, and no relapses have occurred after a median follow-up of 42 months. All four patients who received CBV developed interstitial pneumonitis, and two patients died of pulmonary complications 37 and 48 months following second transplant. Three patients remain alive and disease-free 41, 42 and 155 months after second transplant. These data indicate that second autologous transplantation should be considered for selected patients who relapse after a prolonged response to first autologous transplant. However, BCNU pneumonitis is the major toxicity in patients who have undergone previous mantle radiation and received busulfan with first transplant.

Synthesis of halogen-substituted 3-deazaadenosine and 3-deazaguanosine analogues as potential antitumor/antiviral agents

Various 2-halogen-substituted analogues (38, 39, 43 and 44), 3-halogen-substituted analogues (51 and 52), and 2',3'-dihalogen-substituted analogues (57-60) of 3-deazaadenosine and 3-halogen-substituted analogues (61 and 62) of 3-deazaguanosine have been synthesized as potential anticancer and/or antiviral agents. Among these compounds, 3-deaza-3-bromoguanosine (62) showed significant cytotoxicity against L1210, P388, CCRF-CEM and B16F10 cell lines in vitro, producing IC50 values of 3, 7, 9 and 7 microM, respectively. Several 3-deazaadenosine analogues (38, 51, 57 and 59) showed moderate to weak activity against hepatitis B virus.

Evaluation of fatigue in Parkinson's disease patients with stimulated single fiber electromyography

OBJECTIVES

Fatigue is a disabling and dopa-resistant symptom in Parkinson's disease (PD). Pathological studies have shown that both peripheral and central cholinergic systems are involved in PD. Electrophysiological investigation showed decremental muscle responses following repetitive nerve stimulation (RNS). We hypothesized that fatigue in PD patients may be secondary to cholinergic defect at the neuromuscular level.

MATERIAL AND METHODS

Twenty PD patients with disabling fatigue symptoms were enrolled. We used stimulated single fiber electromyography (s-SFEMG) to evaluate the neuromuscular junction of these patients. For every patient, at least 15 muscle fibers were tested at the rate of 10 Hz with the method described by Trontelj et al. The individual mean consecutive difference (i-MCD) was obtained from 100 constant consecutive single fiber potentials. The i-MCD values in each patient were averaged to obtain the mean MCD (m-MCD).

RESULTS

None of the 20 PD patients with disabling fatigue symptoms had an m-MCD over 29 micros or more than 10% of the i-MCD values over 41 micros. The neuromuscular junction was intact in terms of normal jitter (expressed as MCD) and an absence of blocking.

CONCLUSION

Our findings indicate that the cholinergic system at the neuromuscular level is not affected in PD patients with fatigue symptoms.

3,4-Dihydroxyphenylacetaldehyde and hydrogen peroxide generate a hydroxyl radical: possible role in Parkinson's disease pathogenesis

3,4-Dihydroxyphenylacetaldehyde (DOPAL) and 3,4-dihydroxyphenylglycolaldehyde (DOPEGAL), the monoamine oxidase (MAO) metabolites of dopamine (DA) and norepinephrine (NE), respectively, are toxic to catecholamine (CA) neurons in vitro and in vivo. DOPEGAL generates a free radical and activates mitochondrial permeability transition, a mechanism implicated in neuron death. To determine if DOPAL and other DA metabolites generate the hydroxyl radical in the presence of H(2)O(2), we used HPLC-EC to detect salicylate hydroxylation products. To determine the relative reducing capacity of DOPAL and DOPEGAL we used cyclic voltammetry to measure their reduction potentials. Results indicate that DOPAL, but not DOPEGAL, DA or other DA metabolites, generates hydroxyl radicals. Atomic absorption spectroscopy and heavy metal screening indicate that this result is not due to contamination of DOPAL with iron or other heavy metals. DOPAL reduction potential (161 mV) is lower than that of DOPEGAL (235 mV). DOPAL is present in human substantia nigra. The implications of these findings to CA neuronal death in degenerative brain diseases are discussed.

Synthesis and biological evaluation of L- and D-configurations of 2',3'-dideoxy-4'-C-methyl-3'-oxacytidine analogues

Novel L- and D-configuration 2',3'-dideoxy-4'-C-methyl-3'-oxacytidine and their 5-fluoro analogues have been synthesized from 1-benzyloxy-2-propanone and L-ascorbic acid in eight steps and evaluated for biological activity.

Video-assisted thoracoscopic "resympathicotomy" for palmar hyperhidrosis: analysis of 42 cases

BACKGROUND

There are rare reports of video-assisted thoracoscopic resympathicotomy for patients with palmar hyperhidrosis. I present our experience in treating a persistent or recurrent palmar hyperhidrosis after primary endoscopic sympathectomy or sympathicotomy and discuss the perioperative management.

METHODS

We reoperated on 42 patients using a technique of video-assisted thoracoscopic resympathicotomy. All patients were placed in a semi-sitting position under single- or double-lumen intubated anesthesia. An 8-mm, 0 degrees thoracoscope was used to interrupt the nerve conduction to the palms from the T2 and T3 ganglia, through one or two 0.8-cm subaxillary incisions.

RESULTS

The reasons for failure of endoscopic sympathectomy or sympathicotomy in 26 patients included pleural adhesion (15 of 26, 57.7%), incorrect identification of T2 ganglion (3 of 26, 11.5%), vessel overriding or close to sympathetic nerve (3 of 26, 11.5%), incomplete interruption of sympathetic nerve (2 of 26, 7.7%), medially located sympathetic nerve (2 of 26, 7.7%), and aberrant venous arch (1 of 26, 3.8%). The causes of recurrent palmar hyperhidrosis after primary transthoracic endoscopic sympathicotomy or sympathectomy (TES) in 16 patients included a possible effect of T3 ganglion (8 of 16, 50%), Kuntz fiber (3 of 16, 18.8%), nerve regeneration (3 of 16, 18.8%), and incomplete interruption of T2 ganglion (2 of 16, 12.5%). Surgical complications included pneumothorax (1 patient, 2.4%), hemothorax (1 patient, 2.4%), and compensatory sweating (36 patients, 86%). All patients had obtained successful bilateral sympathectomies and had satisfactory results after a mean of 32.1 months of follow-up.

CONCLUSIONS

Video-assisted thoracoscopic resympathicotomy is an effective and safe method for a previously unsuccessful sympathectomy or recurrent palmar hyperhidrosis if the surgeon acknowledges possible anatomic variations and can overcome the problems related to pleural adhesions.

Endoscopic thoracic sympathetic block by clipping for palmar and axillary hyperhidrosis in children and adolescents

Endoscopic thoracic sympathectomy or sympathicotomy is a safe and effective method of treating primary hyperhidrosis (PH), but postoperative compensatory sweating may be a problem. There are few reports of sympathetic blockade by clipping for PH. We present our experience of endoscopic thoracic sympathetic block (ETSB) by clipping in treating palmar (PAH) and axillary hyperhidrosis (AH) in children and adolescents. Between May 1997 and June 1998, a total of 78 patients with PAH or AH underwent ETSB by clipping using an 8-mm, 0 degrees thoracoscope. There were 33 males and 45 females with a mean age of 14.1 years (range 9-16 y). All patients were placed in a semi-sitting position under single-lumen intubation anesthesia; 52 patients with PAH underwent T2 sympathetic block by clipping at the 2nd and 3rd rib beds, and T3 and T4 sympathetic block was performed at the 3rd, 4th and 5th rib beds in 26 patients with AH. A total of 156 sympathetic blocks by clipping were achieved. The operation was usually accomplished within 20 min (range 16-30 min). Most patients were discharged within 4 h after the operation. There were neither surgical complications nor mortality. The mean postoperative follow-up period was 32.7 months (range 26-40). Improvement of PAH or AH could be obtained in all cases; 70 patients (85.4%) developed compensatory sweating of the trunk and lower limbs. One patient with PAH underwent a reverse operation with improvement of the sweating 14 days after removal of the endo-clips. ETSB by clipping is thus a safe and effective method for treating PH in children and adolescents; compensatory sweating may be improved after a reverse operation with removal of the endo-clip.

Video-assisted thoracoscopic T2 sympathetic block by clipping for palmar hyperhidrosis: analysis of 52 cases

BACKGROUND

Endoscopic thoracic sympathectomy or sympathicotomy is a standard method in treating palmar hyperhidrosis, but postoperative compensatory sweating may be troublesome in some patients. Therefore, we designed a new technique for only T2 sympathetic blocking by clipping instead of interruption of the sympathetic trunk.

PATIENTS AND METHODS

Between September 2000 and July 2001, we saw a total of 100 patients with palmar hyperhidrosis who underwent video-assisted thoracoscopic sympathetic blocking of the T2 ganglion. All patients were placed in a semisitting position under single-lumen intubated anesthesia. We performed sympathetic blocking by clipping of the T2 ganglion at the level of the second and third rib beds using an 8-mm, 0 degree thoracoscope (Storz).

RESULTS

We supposed that the postoperative improvement in palmar hyperhidrosis would be perfect. The operation could be accomplished within 30 minutes. All patients were discharged within 4 hours after the operation. Surgical complications were minimal, without surgical mortality. A few patients were willing to receive the reverse operation and should get improvement of compensatory sweating after removal of the endo clips.

CONCLUSION

We believe that video-assisted thoracoscopic T2 sympathetic block by clipping will be a safe and effective method of treating patients with palmar hyperhidrosis. Compensatory sweating may be improved by the reverse operation: removal of the endo clip.

Fullerenes as a new class of radioprotectors

PURPOSE

To evaluate the radioprotective activity of C3, a regioisomer of water-soluble carboxyfullerene and a potent free radical scavenger, on both normal and tumour cells.

MATERIALS AND METHODS

The murine committed bone-marrow stem cells for both granulocytes and monocytes (GM-CFC) were used to represent normal cells. For tumour cells, murine Ehrlich ascites tumour cells grown in regular tissue culture (EAT-T) and in the peritoneal cavity of CD1 mice (EAT-PC) and human HeLa cells were used. Cells were preexposed to varying concentrations (1-100 microg/ml) of C3 at 37 degrees C for 30 min before they were irradiated. Clonogenic assays were used to determine survival. The protection factor (PF), defined as the ratio of survival with and without C3, was then determined.

RESULTS

C3 protected GM-CFC in a concentration-dependent manner up to 50 microg/ml, and no additional protection was seen at 100 microg/ml. The PF was 1.77 when bone-marrow cells were pre-exposed to 50 microg/ml of C3 before they were irradiated with 2 Gy. The value of PF increased to 2.38 when 4 Gy was used. In sharp contrast, C3 exerted less radioprotective effect on tumour cells. The PF values were 1.07, 1.43 and 1.07 for EAT-T, EAT-PC, and HeLa cells, respectively, when 2 Gy was given in the presence of 50 microg/ml of C3. These values increased to 1.40, 1.75 and 1.27, respectively, when 4Gy was given. The dose-modifying factors at 10% survival were 1.37 and 1.15 for GM-CFC and EAT-PC, respectively.

CONCLUSION

C3 exhibits a radioprotective effect on a class of normal haemopoietic progenitor cells. It also protects tumour cells, but to a lesser degree. It appears that C3 and other water-soluble fullerenes have a potential to be a new class of cytoprotectors.

Endoscopic clipping in video-assisted thoracoscopic sympathetic blockade for axillary hyperhidrosis. An analysis of 26 cases

BACKGROUND

Endoscopic thoracic sympathectomy or sympathicotomy is the standard method for the treatment of axillary hyperhidrosis. But postoperative compensatory sweating may be troublesome in some patients. Therefore, we use endoclips to perform the T3 and T4 sympathetic blockade instead of permanently interrupting the transmission of nerve impulses from the sympathetic trunk.

METHODS

Between May 1997 and June 1998, a total of 26 patients with axillary hyperhidrosis underwent video-assisted thoracoscopic sympathetic blocking of the T3 and T4 ganglia at our hospital. There were 10 men and 16 women with a mean age of 31.7 years (range, 16-47). All patients were placed in a semi-sitting position under single-lumen intubated anesthesia. We performed the sympathetic blockade by clipping the T3 and T4 ganglia at the level of the third, fourth, and fifth rib beds using an 8-mm 0 degree thoracoscope.

RESULTS

Bilateral T3 and T4 sympathetic blockade was achieved in all 26 patients. The operation was usually completed within 30 min (range, 20-42). Most patients were discharged within 4 h after the operation. Surgical complications were minimal, with only one case of segmental atelectasis (3.8%). There were no deaths. The mean postoperative follow-up period was 31.3 months (range, 24-37). Twenty-three patients (88.5%) developed compensatory sweating of the trunk and lower limbs. Twenty-four patients (92.3%) were satisfied with the results of the operation. Improvement of axillary hyperhidrosis was obtained in all patients. One patient underwent a reverse operation to remove the endoclips due to intolerable compensatory sweating; improvement was seen 25 days after removal of the clips.

CONCLUSION

Video-assisted thoracoscopic T3 and T4 sympathetic blockade by clipping is a safe and effective method for the treatment of patients with axillary hyperhidrosis. Patients who experience excessive compensatory sweating may require a reverse operation for endoclip removal.

Pitfalls and complication avoidance associated with transthoracic endoscopic sympathectomy for primary hyperhidrosis (analysis of 2200 cases)

BACKGROUND

Transthoracic endoscopic sympathectomy (TES) has been already a standard method for the treatment of primary hyperhidrosis. There are rare reports about possibly encountered problems during TES. Therefore, we present our experience in treating palmar and axillary hyperhidrosis and discuss the resoluble methods of potential problems during and after TES.

PATIENTS AND METHODS

From June 1994 to October 1999, there were 2200 patients with palmar or axillary hyperhidrosis underwent TES. There are 926 males and 1274 females. Their mean age was 23.4 years old (range: 5-65). All except 12 patients were placed in half-sitting position under single or double-lumen intubation anesthesia. Either a 6-mm or 8-mm, 0degrees thoracoscope, (Karl Storz, Germany) was used to perform sympathectomy thru 0.8 cm incisions below each axilla. Ablation of T2 ganglion was performed in treating patients with palmar hyperhidrosis. Ablation of T3 and T4 ganglia was performed for patients with axillary hyperhidrosis. All except 22 patients were discharged 4 hours after TES, and returned to their activities within one week.

RESULT

Successful sympathectomy were achieved up to 2178 patients (99%), but the rates of incidental unusual findings and possibly encountered problems during TES were 5.6% and 7.1% alternatively. Surgical complications included pneumothorax (10 patients, 0.45%), Hemothorax (2 patients, 0.09%) segmental atelectasis (12 patients, 0.55%), mild wound infection (3 patients, 0.14%) and compensatory sweating (1936 patients, 88%). There was no surgical mortality case. But pleural adhesion (54 patients, 2.45%), repeat sympathectomy (27 patients, 1.23%), obscured upper sympathetic trunk by adipose tissue (22 patients, 1%), medially located sympathetic trunk (18 patients, 0.81%), great vessels overriding or close to the sympathetic trunk (15 patients, 0.68%), aberrant vessels (3 patients, 0.14%), transient bradycardia (3 patients, 0.14%) and re-expansion pulmonary edema (1 patient, 0.05%) might occur during TES.

CONCLUSION

Potential complications may happen during and after TES. But nearly all endoscopic sympathectomy could be achieved if surgeons acknowledge possible anatomic variation and has ability to overcome pleural adhesions.

Gender difference in DNA adduct levels among nonsmoking lung cancer patients

Lung cancer is the leading cause of cancer mortality in Taiwanese women. Cigarette smoking cannot explain the high lung cancer mortality in this population because less than 10% of women in Taiwan are smokers. Therefore, environmental factors other than smoking may play an important role in lung cancer development in female nonsmokers. The purpose of this study was to elucidate the role of environmental carcinogen exposure in lung cancer development in Taiwanese female nonsmokers, based on DNA adduct formation. We collected nontumorous lung tissues resected from 62 nonsmoking lung cancer patients and 20 noncancer controls to investigate whether differences in susceptibility to DNA adduct formation exist between men and women. (32)P-postlabeling and ELISA (enzyme-linked immunosorbent assay) with polyclonal antibody against BPDE (7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene)-DNA adduct were used to evaluate DNA adduct levels in lung tissues of study subjects. Our data showed that the DNA adduct levels of lung cancer patients determined by both assays were significantly higher than those of noncancer controls (P = 0.0001 for (32)P-postlabeling; P = 0.01 for ELISA). Moreover, DNA adduct levels in females were markedly greater than those in males (P = 0.014 for (32)P-postlabeling; P = 0.001 for ELISA). The difference in DNA adduct levels could not be explained by genetic polymorphisms of cytochrome P-4501A1 (CYP1A1) or glutathione S-transferase (GSTM1), as determined by polymerase chain reaction and restriction fragment length polymorphism. These results demonstrate that lung cancer patients have a higher susceptibility to DNA damage than that of noncancer controls. In addition, differences in susceptibility to DNA damage derived from environmental carcinogen exposure were observed between male and female nonsmokers. In conclusion, high susceptibility to DNA damage in females may partially explain the high mortality rate of lung cancer in nonsmoking Taiwanese women.

Transthoracic endoscopic sympathectomy for craniofacial hyperhidrosis: analysis of 46 cases

BACKGROUND AND PURPOSE

Craniofacial hyperhidrosis may result in social phobia and has a strong negative impact on the quality of life. The traditional therapeutic options are psychotherapy and pharmacologic treatment, but these often fail. We wished to investigate whether transthoracic endoscopic sympathectomy (TES) of the lower part of the stellate ganglion is efficient and safe in the treatment of craniofacial hyperhidrosis.

PATIENTS AND METHODS

Between July 1995 and September 1999, a total of 21 men and 25 women with a mean age of 41.2 years (range 22-58 years) underwent TES for craniofacial hyperhidrosis. All patients were placed in a semisitting position under single-lumen intubated anesthesia. We ablated the lower part of the stellate ganglion at the second rib using a storz 8-mm 0 degrees thoracoscope via one 0.8-cm incision just below each axilla. Questionnaires were sent to all patients postoperatively.

RESULTS

Among these 46 patients, 92 sympathectomies were performed. Usually, TES was accomplished within 15 minutes (range 7-20 minutes). The surgical complications were minimal: one segmental atelectasis of the lung (2%). There was no surgical mortality. With a mean postoperative follow-up of 32.1 months (range 3-51 months), the results of TES were highly satisfactory in most patients although 37 (80%) developed compensatory sweating of the trunk and lower limbs, the distribution being the axillae in 15 (33%), back in 36 (78%), lower chest and abdomen in 22 (48%), lower limbs in 34 (74%) and sole in 1. The recurrence rates of craniofacial hyperhidrosis were 0 in the first and the second years and 2% each in the third and fourth years.

CONCLUSION

Transthoracic endoscopic sympathectomy is a safe and effective method for treating craniofacial hyperhidrosis.

Synthesis and biological evaluation of L- and D-configuration 1,3-dioxolane 5-azacytosine and 6-azathymine nucleosides

Novel L- and D-configuration dioxolane 5-azacytosine and 6-azathymine nucleosides have been synthesized and evaluated for biological activity. (-)-(2S,4S)-1-[2-(Hydroxymethyl)-1,3-dioxolan-4-yl]-5-azacytosine (6) showed significant activity against HBV, whereas the D-configuration analogue (14) has been found to exhibit potent anti-HIV activity.