The NADH recycling enzymes TsaC and TsaD regenerate reducing equivalents for Rieske oxygenase chemistry.

Many microorganisms use both biological and nonbiological molecules as sources of carbon and energy. This resourcefulness means that some microorganisms have mechanisms to assimilate pollutants found in the environment. One such organism is Comamonas testosteroni, which metabolizes 4-methylbenzenesulfonate and 4-methylbenzoate using the TsaMBCD pathway. TsaM is a Rieske oxygenase, which in concert with the reductase TsaB consumes a molar equivalent of NADH. Following this step, the annotated short-chain dehydrogenase/reductase and aldehyde dehydrogenase enzymes TsaC and TsaD each regenerate a molar equivalent of NADH. This co-occurrence ameliorates the need for stoichiometric addition of reducing equivalents and thus represents an attractive strategy for integration of Rieske oxygenase chemistry into biocatalytic applications. Therefore, in this work, to overcome the lack of information regarding NADH recycling enzymes that function in partnership with Rieske non-heme iron oxygenases (Rieske oxygenases), we solved the X-ray crystal structure of TsaC to a resolution of 2.18 Å. Using this structure, a series of substrate analog and protein variant combination reactions, and differential scanning fluorimetry experiments, we identified active site features involved in binding NAD+ and controlling substrate specificity. Further in vitro enzyme cascade experiments demonstrated the efficient TsaC- and TsaD-mediated regeneration of NADH to support Rieske oxygenase chemistry. Finally, through in-depth bioinformatic analyses, we illustrate the widespread co-occurrence of Rieske oxygenases with TsaC-like enzymes. This work thus demonstrates the utility of these NADH recycling enzymes and identifies a library of short-chain dehydrogenase/reductase enzyme prospects that can be used in Rieske oxygenase pathways for in situ regeneration of NADH.

Molecular Structure and Conformational Design of Donor-Acceptor Conjugated Polymers to Enable Predictable Optoelectronic Property.

Tuning the optoelectronic properties of donor-acceptor conjugated polymers (D-A CPs) is of great importance in designing various organic optoelectronic devices. However, there remains a critical challenge in precise control of bandgap through synthetic approach, since the chain conformation also affects molecular orbital energy levels. Here, D-A CPs with different acceptor units are explored that show an opposite trend in energy band gaps with the increasing length of oligothiophene donor units. By investigating their chain conformation and molecular orbital energy, it is found that the molecular orbital energy alignment between donor and acceptor units plays a crucial role in dictating the final optical bandgap of D-A CPs. For polymers with staggered orbital energy alignment, the higher HOMO with increasing oligothiophene length leads to a narrowing of the optical bandgap despite decreased chain rigidity. On the other hand, for polymers with sandwiched orbital energy alignment, the increased band gap with increasing oligothiophene length originates from the reduction of bandwidth due to more localized charge density distribution. Thus, this work provides a molecular understanding of the role of backbone building blocks on the chain conformation and bandgaps of D-A CPs for organic optoelectronic devices through the conformation design and segment orbital energy alignment.

Investigation of the Effect of Turn Residues on Tetrapeptide Aldol Catalysts with ß-Turn Propensity.

Peptide catalysts for a wide diversity of reaction types contain a common motif-residues that bias the sequence toward ß-turn secondary structure. In this work, we explore what role that secondary structure plays in the catalysis of aldol reactions for primary amine tetrapeptide aldol catalysts. Using a lead tetrapeptide ß-turn catalytic sequence, we varied the i + 1 and i + 2 residues to amino acids that would affect the ß-turn propensity. We then studied the correlation between secondary structure, aldol rate enhancement, and stereoselectivity of the reaction between hydroxyacetone and 4-nitrobenzaldehyde. Using the i + 3 amide chemical shift as a measure of ß-turn character, we found a rough correlation between the peptide structure and reaction kinetics but minimal effect on stereoselectivity. These trends may help aid the design of future catalytic sequences.

Impairing proliferation of glioblastoma multiforme with CD44+ selective conjugated polymer nanoparticles.

Glioblastoma is one of the most aggressive types of cancer with success of therapy being hampered by the existence of treatment resistant populations of stem-like Tumour Initiating Cells (TICs) and poor blood-brain barrier drug penetration. Therapies capable of effectively targeting the TIC population are in high demand. Here, we synthesize spherical diketopyrrolopyrrole-based Conjugated Polymer Nanoparticles (CPNs) with an average diameter of 109 nm. CPNs were designed to include fluorescein-conjugated Hyaluronic Acid (HA), a ligand for the CD44 receptor present on one population of TICs. We demonstrate blood-brain barrier permeability of this system and concentration and cell cycle phase-dependent selective uptake of HA-CPNs in CD44 positive GBM-patient derived cultures. Interestingly, we found that uptake alone regulated the levels and signaling activity of the CD44 receptor, decreasing stemness, invasive properties and proliferation of the CD44-TIC populations in vitro and in a patient-derived xenograft zebrafish model. This work proposes a novel, CPN- based, and surface moiety-driven selective way of targeting of TIC populations in brain cancer.

The role of ß-hairpin conformation in ester hydrolysis peptide catalysts based on a TrpZip scaffold.

To explore the role of peptide conformation on catalytic activity in the context of ester hydrolysis catalysts, pairs of sequences were designed that contained or lacked ß-hairpin character. For the hydrolysis of para-nitrophenylacetate in aqueous media, we found small but consistent trends wherein His-containing sequences based on a TrpZip scaffold showed higher catalytic activity without ß-hairpin character.

Estradiol Regulation of the Prelimbic Cortex and the Reinstatement of Cocaine Seeking in Female Rats.

Relapse susceptibility in women with substance use disorders (SUDs) has been linked to the estrogen, 17ß-estradiol (E2). Our previous findings in female rats suggest that the influence of E2 on cocaine seeking can be localized to the prelimbic prefrontal cortex (PrL-PFC). Here, we investigated the receptor mechanisms through which E2 regulates the reinstatement of extinguished cocaine seeking. Sexually mature female rats underwent intravenous cocaine self-administration (0.5 mg/inf; 14 × 2 h daily) and extinction, and then were ovariectomized before reinstatement testing. E2 (10 µg/kg, i.p.) alone did not reinstate cocaine seeking, but it potentiated reinstatement when combined with an otherwise subthreshold priming dose of cocaine. A similar effect was observed following intra-PrL-PFC microinfusions of E2 and by systemic or intra-PrL-PFC administration of the estrogen receptor (ER)ß agonist, DPN, but not agonists at ERα or the G-protein-coupled ER1 (GPER1). By contrast, E2-potentiated reinstatement was prevented by intra-PrL-PFC microinfusions of the ERß antagonist, MPP, or the GPER1 antagonist, G15, but not an ERα antagonist. Whole-cell recordings in PrL-PFC layer (L)5/6 pyramidal neurons revealed that E2 decreases the frequency, but not amplitude, of GABAA-dependent miniature IPSCs (mIPSC). As was the case with E2-potentiated reinstatement, E2 reductions in mIPSC frequency were prevented by ERß and GPER1, but not ERα, antagonists and mimicked by ERß, but not GPER1, agonists. Altogether, the findings suggest that E2 activates ERß and GPER1 in the PrL-PFC to attenuate the GABA-mediated constraint of key outputs that mediate cocaine seeking.

Sex, stress, and prefrontal cortex: influence of biological sex on stress-promoted cocaine seeking.

Clinical reports suggest that females diagnosed with substance use disorder experience enhanced relapse vulnerability compared with males, particularly during stress. We previously demonstrated that a stressor (footshock) can potentiate cocaine seeking in male rats via glucocorticoid-dependent cannabinoid type-1 receptor (CB1R)-mediated actions in the prelimbic prefrontal cortex (PrL-PFC). Here, we investigated the influence of biological sex on stress-potentiated cocaine seeking. Despite comparable self-administration and extinction, females displayed a lower threshold for cocaine-primed reinstatement than males. Unlike males, footshock, tested across a range of intensities, failed to potentiate cocaine-primed reinstatement in females. However, restraint potentiated reinstatement in both sexes. While sex differences in stressor-induced plasma corticosterone (CORT) elevations and defensive behaviors were not observed, differences were evident in footshock-elicited ultrasonic vocalizations. CORT administration, at a dose which recapitulates stressor-induced plasma levels, reproduced stress-potentiated cocaine-primed reinstatement in both sexes. In females, CORT effects varied across the estrous cycle; CORT-potentiated reinstatement was only observed during diestrus and proestrus. As in males, CORT-potentiated cocaine seeking in females was localized to the PrL-PFC and both CORT- and restraint-potentiated cocaine seeking required PrL-PFC CB1R activation. In addition, ex vivo whole-cell electrophysiological recordings from female layer V PrL-PFC pyramidal neurons revealed CB1R-dependent CORT-induced suppression of inhibitory synaptic activity, as previously observed in males. These findings demonstrate that, while stress potentiates cocaine seeking via PrL-PFC CB1R in both sexes, sensitivity to cocaine priming injections is greater in females, CORT-potentiating effects vary with the estrous cycle, and whether reactivity to specific stressors may manifest as drug seeking depends on biological sex.

Photophysical and Optical Properties of Semiconducting Polymer Nanoparticles Prepared from Hyaluronic Acid and Polysorbate 80.

A nanoprecipitation procedure was utilized to prepare novel diketopyrrolopyrrole-based semiconducting polymer nanoparticles (SPNs) with hyaluronic acid (HA) and polysorbate 80. The nanoprecipitation led to the formation of spherical nanoparticles with average diameters ranging from 100 to 200 nm, and a careful control over the structure of the parent conjugated polymers was performed to probe the influence of π-conjugation on the final photophysical and thermal stability of the resulting SPNs. Upon generation of a series of novel SPNs, the optical and photophysical properties of the new nanomaterials were probed in solution using various techniques including transmission electron microscopy, dynamic light scattering, small-angle neutron scattering, transient absorption, and UV-vis spectroscopy. A careful comparison was performed between the different SPNs to evaluate their excited-state dynamics and photophysical properties, both before and after nanoprecipitation. Interestingly, although soluble in organic solution, the nanoparticles were found to exhibit aggregative behavior, resulting in SPNs that exhibit excited-state behaviors that are very similar to aggregated polymer solutions. Based on these findings, the formation of HA- and polysorbate 80-based nanoparticles does not influence the photophysical properties of the conjugated polymers, thus opening new opportunities for the design of bioimaging agents and nanomaterials for health-related applications.

Covalent Cross-Linking of Diketopyrrolopyrrole-Based Organogels with Polydiacetylenes.

A new strategy toward functional materials with novel properties and well-defined structures has been developed through the topochemical polymerization of diacetylene-containing diketopyrrolopyrrole (DPP) derivatives. In order to enable the efficient photopolymerization and cross-linking of the materials, a rational design of DPP-based derivatives has been performed to incorporate amide moieties, thus enabling the formation of intermolecular hydrogen bonds and the formation of an organogel. The new materials showed good gelation properties in aromatic solvents, resulting in the formation of a dense fibrous network in the gel state. Upon UV irradiation, the supramolecular self-assemblies obtained were shown to be efficiently cross-linked through the conversion of diacetylene into polydiacetylene. A detailed investigation of new resulting materials was performed by a combination of morphological characterization tools, including X-ray diffraction, Raman spectroscopy, and atomic force microscopy. Our results demonstrate that the topochemical polymerization of diacetylene-containing DPP-based compounds is a promising strategy toward new electroactive and well-defined materials, without the use of catalysts or additives, thus creating new opportunities for the preparation and processing of π-conjugated materials.

17ß-Estradiol Potentiates the Reinstatement of Cocaine Seeking in Female Rats: Role of the Prelimbic Prefrontal Cortex and Cannabinoid Type-1 Receptors.

Clinical observations imply that female cocaine addicts experience enhanced relapse vulnerability compared with males, an effect tied to elevated estrogen phases of the ovarian hormone cycle. Although estrogens can enhance drug-seeking behavior, they do not directly induce reinstatement on their own. To model this phenomenon, we tested whether an estrogen could augment drug-seeking behavior in response to an ordinarily subthreshold reinstatement trigger. Following cocaine self-administration and extinction, female rats were ovariectomized to isolate estrogen effects on reinstatement. Although neither peak proestrus levels of the primary estrogen 17ß-estradiol (E2; 10 µg/kg, i.p., 1-h pretreatment) nor a subthreshold cocaine dose (1.25 mg/kg, i.p.) alone were sufficient to reinstate drug-seeking behavior, pretreatment with E2 potentiated reinstatement to the ordinarily subthreshold cocaine dose. Furthermore, E2 microinfusions revealed that E2 (5 µg/0.3 µl, 15-min pretreatment) acts directly within the prelimbic prefrontal cortex (PrL-PFC) to potentiate reinstatement. As E2 has been implicated in endocannabinoid mobilization, which can disinhibit PrL-PFC projection neurons, we investigated whether cannabinoid type-1 receptor (CB1R) activation is necessary for E2 to potentiate reinstatement. The CB1R antagonist AM251 (1 or 3 mg/kg, i.p., 30-min pretreatment) administered prior to E2 and cocaine suppressed reinstatement in a dose-dependent manner. Finally, PrL-PFC AM251 microinfusions (300 ng/side, 15-min pretreatment) also suppressed E2-potentiated reinstatement. Together, these results suggest that E2 can augment reactivity to an ordinarily subthreshold relapse trigger in a PrL-PFC CB1R activation-dependent manner.

Response to an aerobic training intervention in young adults depends on ponderal index at birth.

Poor fetal growth is associated with later-life changes in adult body composition and decrements in muscle strength and morphology. Few studies have investigated the association of poor fetal growth with whole-body exercise. The purpose of this study was to investigate the association of poor fetal growth with the maximal oxygen consumption (VO(2)max), lactate levels during exercise and the response to aerobic training. Thirty-six college-aged men and women (aged 20.8 ± 0.3 years), born to term (37-42 weeks gestation), were recruited to participate in an 8-week training program. Participants comprised two groups, high ponderal index (HIGHPI) and low ponderal index (LOWPI) (n = 18/group), identified as falling above and below the 10th percentile of the ponderal index (g/cm(3))-for-gestational age distribution, respectively. The HIGHPI and LOWPI were matched pair-wise on age, sex, body mass index and pre-study physical activity patterns. The LOWPI and HIGHPI did not differ significantly before training, after training or with a change (Δ) in training VO(2)max (l/min or ml/min kg/fat-free mass (FFM)). However, LOWPI had significantly lower pre-training lactate levels at similar levels of relative work output (P = 0.016), and significantly smaller decreases in lactate at a fixed level of absolute work after training (P = 0.044). These differences were independent of pre-training aerobic fitness, the change in fitness with training, diet and fuel substrate choice. The lower lactate of untrained LOWPI subjects during exercise could reflect metabolic reprograming due to intrauterine growth restriction, or could be secondary to muscle morphological and/or fiber-type distribution changes that also associate with poor fetal growth.

Classification of births by birth weight and gestational age: an application of multivariate mixture models.

BACKGROUND: Classifications such as low birth weight, premature, and small for gestational age. i.e. compromised births, have been criticized because they depend upon arbitrary standards that may not be appropriate for all populations. AIM: This study applies multivariate Gaussian mixture models with covariates to characterize birth weight by gestational age distributions. SUBJECTS AND METHODS: The data consist of Asian, African, Hispanic and European American births in New York State in 1988. The analysis employs maximum likelihood methods. RESULTS: Birth cohorts appear heterogeneous and composed of at least two sub-populations. One sub-population accounts for the majority of births, has a higher mean birth weight and gestational age but small variances. The other sub-population has a lower mean birthweight and gestational age but very large variances. As a result of the large variances this sub-population accounts for compromised births. The model also suggests that a number of compromised births occur within the normal birth weight and gestational age range. Among normal births, birth weight increases and gestational age declines with maternal age. The effects on compromised births vary among populations. CONCLUSIONS: Multivariate Gaussian mixture models provide a method of identifying compromised births that is not dependent upon arbitrary standards.

Genetic and environmental correlations between various anthropometric and blood pressure traits among adult Samoans.

Shared polygenic effects (i.e., pleiotropy) are assumed to exist for such obesity-related phenotypes as blood pressure and adiposity. It is possible to identify these shared genetic effects through bivariate genetic analyses. This analysis of 1,342 adult Samoans, across 801 pedigrees, indicates that significant heritable components (P < 0.05) ranging from 29-58% exist for weight, height, systolic blood pressure, diastolic blood pressure, triceps skinfold, subscapular skinfold, body mass index, and sum of skinfolds. In general, the anthropometric measurements share additive genetic effects, as do the anthropometric measures, with blood pressure. Heritabilities for central fat distribution are not significant in this population, which could be due to a lack of power. On the other hand, heritabilities have been found in Hispanics; hence the genes responsible for central fat distribution may not be evenly distributed among populations.

Function of the posterior tibial tendon muscle.

The posterior tibial tendon muscle plays a critical role in the function of the foot. It is, with the exception of the triceps surae, the largest of the extrinsic foot muscles. It is called upon to provide a critical posturing and stabilizing function to the foot during gait. This review discusses the anatomy, physiology, functional characteristics, and measurement of the strength of this muscle.

Parkinson's disease: an update for dentists.

One of the diseases that will afflict the growing number of elderly American dental patients is Parkinson's disease, yet few dental articles and textbooks address the condition. This article reviews the clinical and diagnostic features, pathophysiology, management, and dental concerns in patients with Parkinson's disease who undergo dental care.

The 1997 prevention of bacterial endocarditis recommendations by the American Heart Association: questions and answers.

Since the publication of the American Heart Association 1997 recommendations for the prevention of bacterial endocarditis, questions have arisen regarding the application of these guidelines. It is impossible for any such recommendations to include all conceivable clinical situations that might arise, and therefore questions are appropriate. Frequently asked questions are included in this article. Answers provided for the questions are the opinions of the authors, who participated in the formulation of these guidelines, and are not intended to supplant the judgment of the dental health professional who is privy to all the facts when the individual clinical decision is made.

Adverse drug interactions in dental practice. Professional and educational implications.

BACKGROUND: Rapid progress in dental pharmacotherapeutics requires that clinicians constantly update their knowledge of new drugs, drug interactions and useful therapeutic trends. This article is the first in a five-part series based on a 1998 International Association for Dental Research symposium entitled "Adverse Drug Interactions in Dentistry: Separating the Myths From the Facts." The goal of the series is to identify specific adverse drug interactions that are relevant to the therapeutic agents commonly used in general dental practice: analgesics, antibiotics, sedatives, local anesthetics and vasoconstrictors. METHODS: A group of dentist/clinical pharmacologists, with documented expertise in specific areas of dental therapeutics, reviewed the current literature regarding adverse drug interactions in dentistry. This expert panel evaluated the quality of information used to document these drug interactions and assess the severity of these drug reactions with respect to the drugs' use in dental practice. RESULTS: On the basis of the quality and severity of each reported interaction, the authors summarized the clinical importance of these drug interactions using a Significance Rating for Dental Drug Interactions. The participants presented their recommendations at the above-mentioned IADR symposium. CONCLUSIONS: Although thousands of drug interactions are described in the literature, the authors found many to be poorly documented or of minor importance to dental practitioners. For interactions that they determined to be relevant, the participants provided recommendations and precautions for preventing these potential complications. This article discusses the professional impact of drug interactions on dental practice; the classification and documentation of drug interactions; the determination of causality between drug interactions and adverse effects; risk factors; and unique characteristics of dental therapeutics. Subsequent articles will present specific summary recommendations for drug interactions associated with the use of antibiotics, analgesics, sedatives, and local anesthetics and vasoconstrictors. CLINICAL IMPLICATIONS: Although thousands of drug interactions have been reported in the literature, only a few are significantly associated with dental therapeutic agents. Avoiding these drug interactions will prevent potentially severe reactions in dental practice.